#help-with-hw-design | adafruit | Page 52

unreal flax Sep 15, 2021, 2:47 PM

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Typically that would be done with a high-value resistor (10K is typical) tied to ground or to VCC, to pull them low or high as needed.

supple pollen Sep 15, 2021, 4:01 PM

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I usually include one bulk capacitor (generally electrolytic, but there are some nice multilayer ceramic ones available these days as well), and a sprinkling of ceramic 100nF capacitors, generally one for each power pin.

shy rapids Sep 16, 2021, 11:15 PM

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hey what is the best way to make plated vias like a simple way. im using a cnc mill to make simple pcbs rn

unreal flax Sep 16, 2021, 11:17 PM

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shy rapids hey what is the best way to make plated vias like a simple way. im using a cnc m...

They do make miniature rivets which you can use as vias, just using a tool to apply them to a drilled hole on the board.

shy rapids Sep 16, 2021, 11:20 PM

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unreal flax They do make miniature rivets which you can use as vias, just using a tool to ap...

ah chemically

unreal flax Sep 16, 2021, 11:21 PM

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Ah, no idea there, sorry. "Chemically" and "simple" don't usually go together, heh heh.

woeful wyvern Sep 17, 2021, 2:00 AM

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How do you solder a TFT LCD?

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Or is it better to have a connector

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I am thinking about this one

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https://www.digikey.ca/en/products/detail/adafruit-industries-llc/618/8558264

618 Adafruit Industries LLC | Optoelectronics | DigiKey

Order today, ships today. 618 – - Graphic LCD Display Module Transmissive Red, Green, Blue (RGB) TFT - Color SPI 1.8" (45.72mm) 160 x 128 from Adafruit Industries LLC. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

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I want to use it on a PCB

sand summit Sep 17, 2021, 2:03 AM

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thin dia wire and a steady hand, connect to a breadboard or perf with those wires

woeful wyvern Sep 17, 2021, 2:03 AM

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But what if I want to use it on a PCB (finished product)

sand summit Sep 17, 2021, 2:06 AM

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use the mfg’s footprints; if they have none, custom footprint in kicad, not too difficult with a row of pads at a set pitch

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it would be something like this

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(this is a rather unkempt example but it gets the point across)

woeful wyvern Sep 17, 2021, 2:15 AM

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Interesting

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So I guess it isnt the hardest thing in the world

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and maybe I can find a connector

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Thanks

distant raven Sep 17, 2021, 2:23 AM

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Look for FPC connectors @woeful wyvern

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Not saying this is the one you need, but this is an example of an fpc connector I use. https://www.digikey.com/product-detail/en/FH12-24S-0.5SH(55)/HFJ124CT-ND/1110381

woeful wyvern Sep 17, 2021, 2:30 AM

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Great, thanks

limpid nest Sep 17, 2021, 11:19 PM

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If I wanted to do a bunch of designs at once but only one of each, I could do a panel right?

distant raven Sep 17, 2021, 11:19 PM

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Yeah

limpid nest Sep 17, 2021, 11:19 PM

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sweet

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Need to make christmas/holiday gifts for the team

tough matrix Sep 17, 2021, 11:30 PM

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note that many fab houses charge extra if you have more than one design in a panel

limpid nest Sep 17, 2021, 11:39 PM

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interesting

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Well that makes sense

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I like these people so it's worth the expense, within reason

elder peak Sep 18, 2021, 1:28 AM

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Like, most of them don't do a buncha designs. OSHPark will just fab a buncha designs without requiring you to panelize and DirtyPCBs will let you do a panel.

distant raven Sep 18, 2021, 1:30 AM

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@limpid nest you can also ask the OshPark people to see if they will make a mini panel for you

fervent lance Sep 18, 2021, 11:29 PM

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Noob at PCB design

smoky mica Sep 19, 2021, 9:43 PM

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is it bad to route QSPI traces one next to another like this? I feel like ive heard it was bad because of interference but wasn't sure

supple pollen Sep 19, 2021, 10:09 PM

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They're short and low impedance, and they're going to adjacent pins at both ends, it seems totally fine to me. You could look at other boards with QSPI connections to see how they're routed.

distant raven Sep 19, 2021, 10:43 PM

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Seems fine to me

vestal spindle Sep 20, 2021, 12:49 PM

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is there any resources on

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actually learning to use kicad that yall can recommend?

tough matrix Sep 20, 2021, 12:58 PM

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I just used https://docs.kicad.org/
sure, ti was somewhat confusing in the beginning, but in the end I got it

Documentation | KiCad

Documentation for KiCad, the EDA / CAD suite for Windows, macOS, Linux and more.

vestal spindle Sep 20, 2021, 1:05 PM

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thanks

rocky quest Sep 20, 2021, 1:12 PM

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vestal spindle actually learning to use kicad that yall can recommend?

https://www.youtube.com/watch?v=C7-8nUU6e3E

YouTube

Phil’s Lab

KiCad STM32 + USB + Buck Converter PCB Design and JLCPCB Assembly (...

Entire step-by-step PCB design process going through the schematic, layout, and routing of a 'barebones' STM32F4-based PCB including USB and a buck converter in KiCAD. All the way from schematic creation, through to four-layer PCB layout and routing, as well as sending it off for manufacture and assembly via JLCPCB. Visit https://jlcpcb.com/RHS ...

▶ Play video

covert blaze Sep 21, 2021, 6:12 AM

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Good morning people I need some help. I have a circuit with a few op amps that I am supplying with +5V and -5V volt

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The +5V rail works perfectly fine, but as soon as I connect the -5V rail up both the regulator and opamps start to overheat

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+9V comes from battery connected normally with + as +9V and - as the GND. And a second battery as -9V from the - and then + going to GND.

heavy jasper Sep 21, 2021, 6:22 AM

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Are these the actual op amp part numbers you’re using? The lmv722 appears to be a 5V op-amp, which appears to mean here a maximum (V+ - V-) of 5V

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Abs-max V+ - V- of 6V

covert blaze Sep 21, 2021, 6:23 AM

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heavy jasper Sep 21, 2021, 6:23 AM

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So you’ll either need to drop to +/- 2.5V, or change to a different op amp

covert blaze Sep 21, 2021, 6:23 AM

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oh

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So I have to supply -2.5 and + 2.5V ?

heavy jasper Sep 21, 2021, 6:24 AM

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Or choose a pin-compatible op amp with a wider input voltage range

covert blaze Sep 21, 2021, 6:24 AM

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can I use voltage divider from the outpin pins of the regulator to drop down to 2.5?

heavy jasper Sep 21, 2021, 6:26 AM

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I’ll be somewhat inefficient if you want to still have a decent output drive. There are probably pin-compatible voltage regulators too with 2.5V outputs.

covert blaze Sep 21, 2021, 6:27 AM

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Can't believe I missed that while designing the pcb

heavy jasper Sep 21, 2021, 6:27 AM

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But the easiest solution is probably just a new opamp

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No redesigning scale factors of your analog circuit for a different max voltage, and that looks to be a standard footprint so you should have plenty of options

covert blaze Sep 21, 2021, 6:31 AM

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Well thank you Harry I much appreciate it

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I'll desolder these opamps and find replacement for them

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https://www.ti.com/product/TLC2201AM#product-details##params I think this will work

TLC2201AM data sheet, product information and support | TI.com

TI’s TLC2201AM is a Low Noise Precision Advanced LinCMOS™ Single Operational Amplifier. Find parameters, ordering and quality information

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+-16 V

covert blaze Sep 21, 2021, 8:36 AM

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Can't see anything else wrong so here goes attempt #2 blinka_cooking

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tough matrix Sep 21, 2021, 3:11 PM

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Is it realistic to do a home assembly using BGA/WLCSP package?
(To be exact, thsi one: 45 balls, 0.4mm pitch: https://ww1.microchip.com/downloads/en/DeviceDoc/45B_WLCSP_G2B_3_481x2_699mm_C04-21255a.pdf)
Obviously, I'd need a stencil and reflow oven or hotplate... but is it even a possibility or shoudl I just leave it to professionals?

worldly schooner Sep 21, 2021, 3:19 PM

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Precision temperature control can be expensive, but if you have the tools, the process itself is simple.

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Realistically, anyone can do it with the right tools, but from an economic standpoint, it might not be worthwhile for a one-off...?

heavy jasper Sep 21, 2021, 4:31 PM

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It’s probably possible, but if it’s in any way a new design you’re unsure of, IMO adding the extra factor of “did this solder properly” is going to cause a bunch of pain, especially since you can’t inspect the soldering quality.

tough matrix Sep 21, 2021, 4:57 PM

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The problem is, I am looking at an MCU which currently is only available in WLCSP package
If I could choose between that and QFN, obviously I'd choose QFN, but I am not given that choice - unless I am willing to wait until September 2022

worldly schooner Sep 21, 2021, 4:58 PM

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Ooof. PCBA is probably the way to go, but that'll probably hurt your margins somewhat.

brisk hearth Sep 21, 2021, 7:23 PM

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Is EAGLE or Kicad better for beginners?

limpid nest Sep 21, 2021, 7:31 PM

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I have a personal love of Eagle

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Because it's what I was taught

unreal flax Sep 21, 2021, 7:33 PM

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I use Eagle too since I've already learned it, but if you're coming at it fresh, I usually point people to Kicad these days.

limpid nest Sep 21, 2021, 7:33 PM

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interesting

unreal flax Sep 21, 2021, 7:33 PM

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Eagle's days are numbered in Autodesk, IMHO.

haughty wolf Sep 21, 2021, 7:36 PM

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i use kicad and love it. its completely free and has loads of online support and tutorials

limpid nest Sep 21, 2021, 7:38 PM

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You think Autodesk is getting rid of EAGLE entirely??

unreal flax Sep 21, 2021, 7:39 PM

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Not getting rid of it, but completing the integration into Fusion 360, at which point the standalone version will probably be deprecated.

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(Again, just my opinion, not official or anything.)

limpid nest Sep 21, 2021, 7:39 PM

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Ohhh ok

brisk hearth Sep 21, 2021, 7:43 PM

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unreal flax (Again, just my opinion, not official or anything.)

Noooo - that's not good

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F360 is too expensive for me

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So Kicad then

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Are they similar??

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Is it worth it to learn both??

limpid nest Sep 21, 2021, 7:44 PM

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you can get a home use license of F360 for $0

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in the US at least

brisk hearth Sep 21, 2021, 7:45 PM

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Really!!

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I'll have to look into it

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Is it worth it to learn both Kicad and EAGLE?

limpid nest Sep 21, 2021, 7:45 PM

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It probably makes you more employable?

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I don't see a downside other than it being twice as time consuming

brisk hearth Sep 21, 2021, 7:46 PM

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OK - I've got a little free time

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Sounds good - thanks all

haughty wolf Sep 21, 2021, 7:55 PM

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doesnt eagle have a few limits for the free version? i think you can only have a small build area
i'd rather learn kicad at not be at the mercy of a company that only has profits in mind

twilit mango Sep 21, 2021, 7:58 PM

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haughty wolf doesnt eagle have a few limits for the free version? i think you can only have a...

The only thing I ever ran into as a limitation with the free version was mirroring some boards. Not to say there aren't more, I don't do enough with Eagle to be a good resource in that matter.

limpid nest Sep 21, 2021, 7:59 PM

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Eagle also limits layers in the free version, but the pros at adafruit always manage to get what I would do on 4 layers done in 2!

worthy abyss Sep 21, 2021, 8:17 PM

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Are wifi modules, like the ESP32 WROOM, only SMD? :/

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cant find any THT

worthy abyss Sep 21, 2021, 8:39 PM

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KiCad is amazing, i have both KiCad and eagle, but i find KICAD having some weird bugs with the GND when you do the ERC (Electrical Rules Check)

worldly schooner Sep 21, 2021, 8:59 PM

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worthy abyss Are wifi modules, like the ESP32 WROOM, only SMD? :/

Unfortunately, yes. If you want THT you might have to use a prebuilt MCU.

worthy abyss Sep 21, 2021, 8:59 PM

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aah alright :/

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yeah im just thinking of adding a ESP01 to my board, i have that laying around lol

worldly schooner Sep 21, 2021, 8:59 PM

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That being said, castellated holes should be pretty easy to use if you have a half-decent soldering iron.

worthy abyss Sep 21, 2021, 8:59 PM

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i got this one laying around

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im just gonna plug that in i guess 😄

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added 2x4 female headers, and there we go haha

worthy abyss Sep 21, 2021, 9:38 PM

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Hey guys, im slightly confused in Kicad, im trying to add pins for the ESP01 to my atmega328p-pu, but it keeps giving the wrong names on the pins. This is what im trying to follow

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these are my pins

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and this is how i connect them to the Atmega

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but when laying out the board/components, the pins have the wrong names 😅

sand summit Sep 21, 2021, 9:43 PM

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worthy abyss but when laying out the board/components, the pins have the wrong names 😅

the footprint has ground pads that are connected by the ratsnest, you can edit out the pad connections in the footprint editor and number them accordingly

furthermore, the numbering scheme on the schematic is going down the rows like

1 5 2 6 3 7 4 8

but the footprint has them numbered

7 8 5 6 3 4 1 2

worthy abyss Sep 21, 2021, 9:44 PM

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oh i should get a different footprint? 😄

sand summit Sep 21, 2021, 9:44 PM

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you can just edit it to match the numbering scheme of the actual footprint

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prolly better to edit the schematic symbol to match the diagram’s pinout

worthy abyss Sep 21, 2021, 9:45 PM

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ohgod, im new to Kicad so its gonna be fun figuring this all out CoconaSweat

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well, im inside the footprint editor

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and i selected the correct component, do i just drag and drop the numbers on the correct spot? 😅

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Got it thumbsupgif

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awesome! @sand summit Thank you so much, it worked, i created a custom Connector and a custom footprint branching off of the original ones. And now they correctly connect ^_^

sand summit Sep 21, 2021, 10:16 PM

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worthy abyss awesome! <@!484881550354415626> Thank you so much, it worked, i created a custom...

sounds great! np 👍

worthy abyss Sep 21, 2021, 10:18 PM

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^_^

worthy abyss Sep 21, 2021, 11:21 PM

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Is there someone that does like, PCB overview? I need a review since this is my first PCB, and i would like to know if stuff is connected properly 😊

pale current Sep 21, 2021, 11:22 PM

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worthy abyss Is there someone that does like, PCB overview? I need a review since this is my ...

You can always post it here and people may look at it. I don't want to say I can be a good source as I'm only on PCB #3 🙂

worthy abyss Sep 21, 2021, 11:23 PM

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hahaha, is it better to just post pics, or to upload the actual Kicad file? 😄

pale current Sep 21, 2021, 11:23 PM

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im not sure the pictures may work fine as long as they are large enough. If someone wants to go more into it they could ask for the files or just link to them i guess

worthy abyss Sep 21, 2021, 11:24 PM

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alright ^^

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welp here goes nothing 😛

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worldly schooner Sep 21, 2021, 11:26 PM

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WiFi controlled neopixel board?

worthy abyss Sep 21, 2021, 11:26 PM

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the most terrible job of connecting 🙃

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haha no, its for WS2812 led strips 😄

worldly schooner Sep 21, 2021, 11:28 PM

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Adafruit neopixels include ws2812

worthy abyss Sep 21, 2021, 11:28 PM

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yeah but i have actual strips 😄

worldly schooner Sep 21, 2021, 11:28 PM

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Using a dip switch for reset?

worthy abyss Sep 21, 2021, 11:29 PM

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Yeah i didnt know what the best way is to do it

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(i also forgot to add UART, will add that next hehe)

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theres no way to upload code atm

worldly schooner Sep 21, 2021, 11:29 PM

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Well most people use a more accessible tactile switch

worthy abyss Sep 21, 2021, 11:30 PM

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hmmm

worldly schooner Sep 21, 2021, 11:30 PM

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And r3 should be a pull-up, but your switch instead shorts 5v to ground

worthy abyss Sep 21, 2021, 11:30 PM

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i knew it, i knew something about that was wrong lol

worldly schooner Sep 21, 2021, 11:31 PM

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Your voltage divider converts your 5v to 3v, not 3.3v

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And it’s probably better to just use an LDO regulator instead for better voltage stability

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I would not use a passive divider for power.

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The capacitors are probably going to be unpolarized MLCC, so I would make sure your footprint isn’t expecting a big cylindrical capacitor.

worthy abyss Sep 21, 2021, 11:34 PM

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i checked, they are the small orange ones :3

worldly schooner Sep 21, 2021, 11:34 PM

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Ok cool

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And last but not least, what is GPIO0, and why is it connected to ground?

worthy abyss Sep 21, 2021, 11:35 PM

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i saw it here 😮

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worldly schooner Sep 21, 2021, 11:36 PM

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I ask because I don’t know either.

worthy abyss Sep 21, 2021, 11:36 PM

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oh haha 😄

worldly schooner Sep 21, 2021, 11:36 PM

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If you don’t know why though, it’s good to check and see.

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I would if I weren’t on mobile

worthy abyss Sep 21, 2021, 11:37 PM

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But to sum up:

Change reset DIP to tactile switch
Change R3 to be a pull-up resistor
Change voltage divider to a LDO regulator

worldly schooner Sep 21, 2021, 11:38 PM

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OH

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How are you going to program your two chips

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Esp01 comes with at firmware iirc but your atmega328p doesn’t seem to have any prog pins

worthy abyss Sep 21, 2021, 11:39 PM

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Yeah i forgot the stuff :/

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i was so enthusiastic that i forgot that lol

worldly schooner Sep 21, 2021, 11:40 PM

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You also don’t seem to have a connector for a power connection

worthy abyss Sep 21, 2021, 11:40 PM

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There should be, on the bottom under the crystal J4

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5v terminal block

worldly schooner Sep 21, 2021, 11:41 PM

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Sorry, regulator not connector

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Are you using a strictly 5v supply?

worthy abyss Sep 21, 2021, 11:41 PM

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well its like a meanwell 5v supply

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like this

worldly schooner Sep 21, 2021, 11:42 PM

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Aight then

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That’s all I got for now

worthy abyss Sep 21, 2021, 11:42 PM

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hmm alright, these are gonna be big changes haha

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i found this for the GPIO0 pin btw

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o

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Well, thanks for the tips btw! Appreciate them 😄 gonna write them down and fix them :3

worthy abyss Sep 22, 2021, 12:26 AM

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worldly schooner That’s all I got for now

I added the suggested changes, how does it look now? 😄

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Added a LDO regulator, which takes in 5v and outputs 3.3v 500mA (ESP01 uses like 250mA, but sometimes spikes to 500mA)
Changed the DIP switch to a tactile switch

Still gotta change the pullup resistor on the reset and add the UART programming interface 😅

distant raven Sep 22, 2021, 12:46 AM

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Does anyone have experience with TFT displays? I’m making a design for someone and I’m failing to get the TFT to power on. I mirrored the Adafruit design using a similar FPC connector. Only difference in my design is one of the pins they left floating I connected to ground.

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U3 is a supervisor IC

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The BSS138 N-Channel mosfet I had to find a physical replacement for

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I’m using a DMN65D8L

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60V 310mA N-CH mosfet

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Modeled after the Adafruit breakout: https://learn.adafruit.com/assets/79156

worldly schooner Sep 22, 2021, 12:56 AM

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What kind of TFT are you using?

distant raven Sep 22, 2021, 1:02 AM

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1.3” ST7789 240x240 pixel TFT

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Same one Adafruit is using in that schematic I linked

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I verified the displays I bought work in with the Adafruit breakout

worldly schooner Sep 22, 2021, 1:04 AM

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And you verified the contact side for the FPC connector is the same?

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I don't have an Adafruit breakout to verify

distant raven Sep 22, 2021, 1:05 AM

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Yeah,

worldly schooner Sep 22, 2021, 1:06 AM

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Do you get anything? Backlight, at least?

distant raven Sep 22, 2021, 1:06 AM

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No backlight

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I’ve checked the solder connection to the board for the FPC connector too.

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3V pins and GND pins prob right

worldly schooner Sep 22, 2021, 1:08 AM

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Is reset pulled low or high?

distant raven Sep 22, 2021, 1:09 AM

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Low active

worldly schooner Sep 22, 2021, 1:09 AM

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Adafruit breakout pulls it up to logic high

distant raven Sep 22, 2021, 1:09 AM

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So pulled high

worldly schooner Sep 22, 2021, 1:09 AM

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Is it properly going low when you turn it on?

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(Oh I see the pullup woops)

distant raven Sep 22, 2021, 1:12 AM

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Pulled high

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3.3 V on reset line

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Line for the ledk line is 0V

worldly schooner Sep 22, 2021, 1:14 AM

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And no backlight at all?

distant raven Sep 22, 2021, 1:14 AM

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Nope

worldly schooner Sep 22, 2021, 1:15 AM

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Weird, usually it at least leaks out the side...

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Did you verify the SPI bus?

distant raven Sep 22, 2021, 1:16 AM

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in terms of the pin choice?

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yeah, the SPI pins are chosen from what worked on a breadboarded prototype

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Screen_Shot_2021-09-21_at_7.15.54_PM.png

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adafruit's design for reference

Screen_Shot_2021-09-21_at_7.18.32_PM.png

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wait, should have done ratsnest hold on

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Screen_Shot_2021-09-21_at_7.19.22_PM.png

worldly schooner Sep 22, 2021, 1:22 AM

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Oh wait, Adafruit grounds pin 5

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You grounded pin 3

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I think you selected the wrong bus

distant raven Sep 22, 2021, 1:23 AM

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their pin 3 is grounded

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Screen_Shot_2021-09-21_at_7.23.52_PM.png

worldly schooner Sep 22, 2021, 1:24 AM

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Agh

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wrong schematic

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Looked at 1.54

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Why are there only 21 pins tho...

distant raven Sep 22, 2021, 1:25 AM

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pin 22 is hanging

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gnd is 3 * 3 meaning 3 pins are appending to it

worldly schooner Sep 22, 2021, 1:25 AM

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Ahhhh

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Well I got nothing left

distant raven Sep 22, 2021, 1:27 AM

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only thing i can think of is I need different FPC connectors. it has top and bottom pins in the opening but i don't really know how to tell if they are actually making contact

worldly schooner Sep 22, 2021, 1:27 AM

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The Hirose should be bottom only IIRC

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Are the contacts facing up when you insert it?

distant raven Sep 22, 2021, 1:29 AM

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yeah, it's wrap around

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dang, i really should have looked. it's bottom contact

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okay, found some top contact ones. wish me luck lol..

limpid nest Sep 22, 2021, 2:32 AM

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What layer in eagle represents the board?

distant raven Sep 22, 2021, 2:33 AM

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Dimension represents the outline

limpid nest Sep 22, 2021, 2:33 AM

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ok, I'm trying to use SVGToEagle to create a board outline

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I'm making coronavirus shaped coasters out of PCB for friends who survived the virus

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Is this color normal for Eagle in Fusion? for the Dimension layer?

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I'm used to black

distant raven Sep 22, 2021, 2:49 AM

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My dimension layer is usually yellow

tough matrix Sep 22, 2021, 2:56 AM

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Electronics component of Fusion 360 uses different colors than standalone Eagle

distant raven Sep 22, 2021, 2:57 AM

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Ah true

limpid nest Sep 22, 2021, 3:16 AM

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Where in heaven did they move the ratsnest tool to?

distant raven Sep 22, 2021, 3:17 AM

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Tools?

limpid nest Sep 22, 2021, 3:17 AM

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Here's my view

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All the tools I'd expect to be around ratsnest are there, but no ratsnest

limpid nest Sep 22, 2021, 9:10 PM

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Hm, I found advice to upload libs I want to use to my project folder, but that didn't make the lib available

empty hollow Sep 23, 2021, 5:31 PM

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Question, I have a prototype device that has a microcontroller, lipo battery, and charging chip. It randomly dies sometimes when connected or disconnected from charging. It seems to be very random. I think its due to noise or ESD. Should I turn on WTD and BOD to solve the issue? Do production products generally have these features enabled?

worldly schooner Sep 23, 2021, 6:08 PM

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empty hollow Question, I have a prototype device that has a microcontroller, lipo battery, an...

I don't think I recognize either of those terms, but my first thought would be to look at bypass capacitors to reduce the transient spike that occurs when the charger is connected?

empty hollow Sep 23, 2021, 6:10 PM

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watch dog timer and brown out detect

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that was my thought as well but scoping the supply, I dont see any major dips or transients

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I also have 1uf and 0.1uf cap

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But the issue is very random and doesnt happen on my bench.

worldly schooner Sep 23, 2021, 6:13 PM

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Ah, depends on the chip then. Which charging chip are you using?

empty hollow Sep 23, 2021, 6:28 PM

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tp4056

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and the microcontroller is an 8bit 8051 based

worldly schooner Sep 23, 2021, 6:40 PM

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Well it's got an under-voltage lockout. No watchdog timer. If you don't see any dips it's probably not UVLO though....

sweet inlet Sep 23, 2021, 7:30 PM

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Anyone else accidentally burn gunk onto their hot plate? And advice for how to clean?

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distant raven Sep 23, 2021, 7:40 PM

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sweet inlet

Steel wool?

worldly schooner Sep 23, 2021, 7:46 PM

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Isopropyl? Acetone might be too strong, depending on what type of surface finish your plate has

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What kind of gunk are we talking?

sand summit Sep 23, 2021, 7:46 PM

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perhaps burnt on flux residue?

sweet inlet Sep 23, 2021, 7:50 PM

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I think it is burnt on flux

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The isopropyl on hand is 70%, hasn’t been very effective; getting stronger stuff in a few days

#

Might give steel wool / acetone a try. I think it’s just a machined finish, not sure if there’s anything applied to it per se

sand summit Sep 23, 2021, 7:52 PM

#

if it's bare metal, for sure give acetone a shot with something abrasive like fine steel wool

unique patio Sep 23, 2021, 7:53 PM

#

or a razor-blade scraper if it's not too soft

sweet inlet Sep 23, 2021, 8:04 PM

#

Found some left over adhesive remover (isopropyl and acetone mix) when looking for the steel wool, just needed a quick scrub!

#

Thanks all!

limpid nest Sep 23, 2021, 8:14 PM

#

Does anyone know of any cable glands for flat, two conductor cabling?

#

Or similar product. Something IP rated if possible

limpid nest Sep 23, 2021, 8:31 PM

#

nevermind, I was searching the wrong thing

worthy abyss Sep 24, 2021, 10:26 PM

#

Hey guys, on my standalone atmega328pu, i got these connections (RX, TX) running to my ESP01.

But... how do i make those pins from the atmega328 also available for uploading to the Atmega328p-pu directly? Can i just literally connect onto those lines? or do i have to split something?

#

#

also, i think with this setup, the GPIO0 pin is always pulled high, right? which means it will stay in flash mode, and not program mode, so i guess i have to add something for that aswell :/

opal jay Sep 25, 2021, 1:06 AM

#

Was just working on making my own Arduino Mega and was wondering if this was correct so far? The Crystal is https://www.mouser.com/ProductDetail/ECS/ECS-160-18-4X-CKM?qs=7MVldsJ5UawYqyimirccKw%3D%3D . Thanks

Mouser Electronics

ECS-160-18-4X-CKM ECS | Mouser

supple pollen Sep 25, 2021, 1:35 AM

#

I would suggest making the ground trace thicker (or a pour)

opal jay Sep 25, 2021, 1:40 AM

#

will do, just thought .6mm (0.015 inch) traces would be good enough (1.2 amps at 1oz). At least according to https://www.pcbcart.com/article/content/copper-trace-and-capacity-relationship.html

Relationship between Copper Weight, Trace Width and Current Carryin...

Relationship between PCB Copper Foil Cross-Sectional Area and Maximum Current Carrying Capacity and Temperature Rise. Also introduce elements Determining Maximum Current Carrying Capacity.

#

guess the original Mega had some 5V rails at 1.2mm

#

(though, they split off)

#

might as well go big ha

#

other than that, if that looks good I'll start figuring out/designing the USB interface part

supple pollen Sep 25, 2021, 2:09 AM

#

I meant the thin one under the crystal

opal jay Sep 25, 2021, 2:10 AM

#

gotcha, still, think I should make all the GND/5V larger, especially since it won't hinder the rest of it at all

worthy abyss Sep 25, 2021, 9:37 AM

#

hey guys, on my previous question, how do i swap the RX/TX mode? I have a standalone ATMEGA328P-PU, but i have a ESP01 connected to its RTX/TX pins.

Issue is, i also need to use those pins to upload code to the Atmega, how do i make a switch to say like ok; I want to upload code to the Atmega now, and after that, i just want the normal working of the Atmega with the ESP01

#

supple pollen Sep 25, 2021, 1:29 PM

#

The original Arduino had 1k decoupling resistors to allow the GPIO signals (if driven) to override the serial signals. You might be able to do the same if you can get the ESP to not drive the signals. In your case it's somewhat further complicated by the voltage divider resistors, which could double as decoupling resistors but I'm not sure how it would all work out.

heavy jasper Sep 25, 2021, 4:12 PM

#

You can also add in a level shifter with enable pin.

#

It’s probably more expensive, but an assured solution. Atmega controls said enable pin, with a pull resistor that keeps it disabled by default until the atmega drives the enable line when it wants to talk to the esp32.

#

Alternatively, you can use SoftwareSerial or similar library, and an entirely different set of pins.

#

(Or a different microcontroller; IMO even for Arduino-compatibility, the 328p is somewhat long in the tooth)

worthy abyss Sep 25, 2021, 4:44 PM

#

so, what about putting my Atmega inside the arduino, program it like it has to be programmed, and then just... put it back in the slot?

#

basically, im not gonna solder the arduino on the PCB, im gonna add a socket in there for it 😄

#

and i can avoid the Pins for 'programming' the atmega as i program it inside the arduino 😄

long wraith Sep 25, 2021, 4:57 PM

#

If it's socketed, and something that's mostly program once and use forever, that sounds entirely reasonable

worthy abyss Sep 25, 2021, 5:09 PM

#

awesome, will do that to save alot of hassle 😛

#

Just one more thing, would this be ok for the RESET button?

distant raven Sep 25, 2021, 5:41 PM

#

Errr no

#

Close

distant raven Sep 25, 2021, 5:43 PM

#

worthy abyss Just one more thing, would this be ok for the RESET button?

Reset lines have pull ups like this

#

Don’t mind the capacitor, it’s not necessary for atmega328p

worthy abyss Sep 25, 2021, 7:12 PM

#

Ohh ! Nice! I should apply that :o

heavy jasper Sep 25, 2021, 9:16 PM

#

It would work if you program once and use forever, but that sounds like a miserable experience for developing SW for this.

#

(you have to keep switching the 328P between the arduino for programming, then back to your board)

#

if you've completely written all the SW already with dev kits and breadboards, could work, but at least for stuff I'm working on I strongly prefer to not cut down on my options like that.

#

Can you leave the ICSP pins exposed?

#

I think Arduino supports direct-loading firmware as well (not just bootloader) so if you have an ICSP programmer that could be an option, or possibly you could get away with your divider and then a larger series resistor on TX_ESP as long as your UART is strong enough (and it should be).

#

Ideally you'd then use a 3.3V over-voltage tolerant UART bridge, since w/ 5V you'd be relying on the series resistance and internal ESD protection diodes on the ESP32 to make it not blow up.

#

I'd only be confident in that strategy if the ESP32 datasheet calls out a specific maximum injection current per I/O pin, and (5V - 3.3V) / (Rseries on TX_ESP) is less than said injection current.

limpid nest Sep 25, 2021, 9:22 PM

#

I'm looking to mount a TLC59711 on a board and breakout rgb0-3 as well as v+. If I'm expecting 15mA current from each "LED" (I'm driving relays), can I get away with only having one trace from one of the v+ pins? Or should I connect all the pins on my board at their contact points as well?

#

If it's a thickish trace?

heavy jasper Sep 25, 2021, 9:26 PM

#

I'm not sure what you mean by "the V+ pins" in this context

limpid nest Sep 25, 2021, 9:26 PM

#

Oh, it's the power supply for the LEDs

#

Sorry, I slept weird, I'm not communicating well

heavy jasper Sep 25, 2021, 9:27 PM

#

Are they actually LEDs, or are they relays?

limpid nest Sep 25, 2021, 9:27 PM

#

Oh yes relays

heavy jasper Sep 25, 2021, 9:27 PM

#

Okay, so the TLC59711 is a somewhat interesting choice for that application

#

built-in PWM when driving relays can be... adventurous if you're not specifically looking to use that feature.

#

Might I suggest something like: https://assets.nexperia.com/documents/data-sheet/NPIC6C595.pdf

#

It has the advantage of being ~1/4 the cost

limpid nest Sep 25, 2021, 9:28 PM

#

Yeah a friend recommended it and then I put it on a spreadsheet that my boss thought was a purchase request and he bought a bunch. but there's a circuitpython lib for them so that made it easy to choose.

heavy jasper Sep 25, 2021, 9:29 PM

#

If this is for a work application, I'm not sure how many you bought but I would strongly advise just ditching them and going with something simple like the NPIC6C595

#

which looks just like a shift register

#

so I suspect there's a circuitpython library for that as well

#

The possible grounds for subtle bugs and weirdness trying to use something designed as an LED driver for a highly inductive load like a relay means that you could very quickly waste more than the value of parts in time.

limpid nest Sep 25, 2021, 9:30 PM

#

Interesting

#

I wish I'd consulted this place earlier. Well, I'm ahead of schedule so it's OK.

#

Would I need to write a custom circuitpython library to run it? It looks like there's only an arduino lib for a similar but not the same chip

#

Are these shift registers more suited to switching relays than other shift registers?

heavy jasper Sep 25, 2021, 9:32 PM

#

Yes, these are specifically open-drain outputs with robust output clamping

limpid nest Sep 25, 2021, 9:32 PM

#

ok the original design used normal shift registers

#

So, I'm currently refurbishing a design to get it ready for public use ASAP, but we are duplicating the existing hardware for two other properties, so I can get fancy there. Is the PWM method, even with a fully duty cycle, likely to just plain not work?

heavy jasper Sep 25, 2021, 9:33 PM

#

This looks like it should map 1:1 with the library here: https://learn.adafruit.com/74hc595/usage

Adafruit Learning System

74HC595 Shift Register

Add lots more outputs to a microcontroller system with chainable shift registers.

limpid nest Sep 25, 2021, 9:33 PM

#

Ahhh, so I'd need to make a breakout board of my own probably? Or buy some DIP sockets?

heavy jasper Sep 25, 2021, 9:34 PM

#

No, the DIP chips there are just for the SW demo

#

which uses a breadboard

limpid nest Sep 25, 2021, 9:34 PM

#

OH I see these are SMD

#

So we're back in the land of making my own board again

#

shoot

heavy jasper Sep 25, 2021, 9:35 PM

#

If you must have DIP: TPIC6B595N

#

Pretty much the same part but made by TI and PDIP20

limpid nest Sep 25, 2021, 9:36 PM

#

OK and how are these configured, SPI?

#

Let me read before asking questions actually

#

thank you so much!

heavy jasper Sep 25, 2021, 9:36 PM

#

Same deal, shift register interface

#

(so kind of spi but not quite; but there's a circuitpython library for it)

limpid nest Sep 25, 2021, 9:36 PM

#

SPI is kind of a fancified shift register protocol right?

heavy jasper Sep 25, 2021, 9:36 PM

#

It has more overhead, and you don't get for-free handling of the surrounding signals these shift registers use for output enable, async reset, etc

limpid nest Sep 25, 2021, 9:37 PM

#

Oh how many bits are these?

heavy jasper Sep 25, 2021, 9:38 PM

#

8 outputs per

limpid nest Sep 25, 2021, 9:38 PM

#

8 bit? So I could use 2 for 12?

heavy jasper Sep 25, 2021, 9:38 PM

#

yeah

limpid nest Sep 25, 2021, 9:38 PM

#

so what is it about a relay load that is bad for using an LED switcher to control it?

heavy jasper Sep 25, 2021, 9:39 PM

#

What's the supply voltage of the relay?

limpid nest Sep 25, 2021, 9:39 PM

#

5V

#

it's switching 110AC

heavy jasper Sep 25, 2021, 9:39 PM

#

In short: the led switcher is not intended for operation with an inductive load; inductive loads "kick" when you let go due to the collapsing magnetic fields in the coil inductance

limpid nest Sep 25, 2021, 9:39 PM

#

ahh ok so I'll damage the part?

heavy jasper Sep 25, 2021, 9:40 PM

#

It could potentially damage the part, and more so I'm not as confident out of the box saying "for sure I can just add a kickback diode and call it a day"

#

e.g. maybe the LED driver really doesn't like having its outputs driven above the supply voltage at all, or you're now competing between your external protection diodes and the internal ESD protection diodes in the LED driver

limpid nest Sep 25, 2021, 9:40 PM

#

ahhh ok, well it's rated for controlling 4-17 volts, does that mean anything?

#

but is it specifically the kick above supply from the field collapsing that's a problem?

heavy jasper Sep 25, 2021, 9:42 PM

#

Most commonly, yes. Where PWM just makes this worse by making it happen much more often.

#

(in fact, it starts to look a lot like a boost converter)

limpid nest Sep 25, 2021, 9:42 PM

#

ahh ok

heavy jasper Sep 25, 2021, 9:42 PM

#

PWM has its purpose in driving relays, especially huge ones

limpid nest Sep 25, 2021, 9:42 PM

#

That makes sense. I studied mechanical engineering forever ago and only really had a few weeks where we covered power electronics

heavy jasper Sep 25, 2021, 9:42 PM

#

people will do clever tricks to save power by first using a huge voltage to force the relay to change over, then drop down to a lower average current to keep the relay held in place

limpid nest Sep 25, 2021, 9:42 PM

#

interesting

heavy jasper Sep 25, 2021, 9:43 PM

#

But again, typically that's on a designed-for-purpose sort of system

limpid nest Sep 25, 2021, 9:43 PM

#

For sure

#

Well it was useful to have the boards to test my code, now I have the bones of something that works, so it wasn't a huge waste of time

#

and the property I work on has plenty of uses for LEDs 🙂

heavy jasper Sep 25, 2021, 9:44 PM

#

I'm taking a look at the datasheet, it's not quite clear what's allowed on the output side. They only call out the spec vs. other output channels

#

Ohhh I see

#

that's them enumerating output types

#

okay, so yes this is safe to 17V directly, not just VCC.

#

So I'd still want an external protection diode as good practice, but w/ a 5V driven relay, it should be okay.

limpid nest Sep 25, 2021, 9:46 PM

#

How would the protection diode be wired? My town still has a radioshack so I bet I could grab a few dozen

heavy jasper Sep 25, 2021, 9:46 PM

#

Across the relay

limpid nest Sep 25, 2021, 9:47 PM

#

OK, they seem to have just two inputs, 5V and GND

heavy jasper Sep 25, 2021, 9:47 PM

#

Yep, so directly from 5V to GND of the relay; its purpose is to continue to allow current to flow in the same direction it's flowing when the relay is on

limpid nest Sep 25, 2021, 9:48 PM

#

They may have those?

#

THey are sparkfun relays

#

I'm away from work now, but I can post them here monday.

heavy jasper Sep 25, 2021, 9:50 PM

#

In any case (courtesy Wikipedia):

#

That's what you want

limpid nest Sep 25, 2021, 9:51 PM

#

which is accomplished by putting a diode rated for something way over 5V, like 15V, between 5V and GND?

heavy jasper Sep 25, 2021, 9:52 PM

#

It doesn't actually need to be rated for way over 5V; technically just 5V

#

(since the DC reverse voltage it sees should is only ever 5V; it's forward-biased when it's taking the brunt of the kickback)

#

but it's good practice to have some derating due to how things can ring around w/ the capacitance of the diode and such, so 15V seems well-safe.

#

Most folks tend to use something like: https://www.adafruit.com/product/755

1N4001 Diode - 10 pack

This here is a 10 pack of the classic 1N4001 power blocking diode. These are good for reverse polarity protection (put it between your DC power jack and circuitry to avoid a negative-voltage ...

#

It doesn't need to be super fancy

limpid nest Sep 25, 2021, 9:55 PM

#

Like this or swapped?

heavy jasper Sep 25, 2021, 9:55 PM

#

Other way

limpid nest Sep 25, 2021, 9:56 PM

#

I always mix up diodes, it's bad. I internalized it wrong the first time and it's stuck pretty bad

#

Thank you for your help!

brisk hearth Sep 25, 2021, 10:01 PM

#

limpid nest I always mix up diodes, it's bad. I internalized it wrong the first time and it'...

oof

distant raven Sep 25, 2021, 10:19 PM

#

I always remember that usually the line of the diode faces the side you want to block.

#

So a Schottky diode on a VUSB line would have the line on the 5V side if you label VUSB in and 5V through.

brisk hearth Sep 25, 2021, 10:20 PM

#

distant raven I always remember that *usually* the line of the diode faces the side you want t...

Like a wall

distant raven Sep 25, 2021, 10:21 PM

#

There are instances where you would put the diode the other way but I can’t remember the reasons for that though.

brisk hearth Sep 25, 2021, 10:25 PM

#

distant raven There are instances where you would put the diode the other way but I can’t reme...

Yeah.... I've never done that

distant raven Sep 25, 2021, 10:26 PM

#

Same

brisk hearth Sep 25, 2021, 10:26 PM

#

distant raven Same

https://tenor.com/view/why-would-you-do-such-a-thing-liane-cartman-eric-cartman-south-park-s10e7-gif-20852844

Tenor

worthy abyss Sep 25, 2021, 10:48 PM

#

heavy jasper Can you leave the ICSP pins exposed?

Woul that be the

SCK
MOSI
MISO

pins? if so, I'm using the MOSI pin (PWM) already as a data output for my led strip 😅

heavy jasper Sep 26, 2021, 1:46 AM

#

Usually when you're putting diodes in the other direction they're zener diodes which have a fixed reverse breakdown voltage (and that voltage is useful in some way)

#

I believe that those are the pins for an atmega, yes.

inland jungle Sep 26, 2021, 2:29 AM

#

I think the zeners still go in the same direction.

heavy jasper Sep 26, 2021, 2:30 AM

#

More so: zeners are the only* time you expect and are looking for reverse current through a diode.

supple pollen Sep 26, 2021, 3:03 AM

#

Heh that asterisk

worthy abyss Sep 26, 2021, 6:28 PM

#

distant raven Reset lines have pull ups like this

Hi! I did it on this way now, is it better? 😄

distant raven Sep 26, 2021, 6:29 PM

#

Yeah, much better. The capacitor from my understanding is just a smoothing capacitor so you don’t get weird signal bounce when you press the button

worthy abyss Sep 26, 2021, 6:29 PM

#

Ah right! Thats why its a polarized cap, right?

distant raven Sep 26, 2021, 6:30 PM

#

No, it should be ceramic

worthy abyss Sep 26, 2021, 6:31 PM

#

ceramic like this yeah

distant raven Sep 26, 2021, 6:32 PM

#

In eagle, they use the symbol that is generally referred to as a polarized cap. I’ll usually specify the type in the BOM though

worthy abyss Sep 26, 2021, 6:32 PM

#

hmm alrighty

distant raven Sep 26, 2021, 6:32 PM

#

Yeah, it’s weird

#

If I use polarized caps, I try to find ones labeled with a +/- on it

worthy abyss Sep 26, 2021, 6:34 PM

#

well yeah, i find connecting it in the pcb thing so weird, the ratsnest is just, annoying to use lol, but so far connecting it

#

as u can see, bottom left is the actual reset pin input

vagrant pecan Sep 26, 2021, 7:25 PM

#

Has anyone out there already made an Eagle footprint for the QT Py RP2040?

I have one for the SAMD21 version, but it would need some cutouts for the chips on the RP2040

#

Clarification - I want to SMD mount the QTPy with the castellated pads

distant raven Sep 26, 2021, 7:31 PM

#

I have a library for eagle i'll share

#

just adding a dimension cutout

vagrant pecan Sep 26, 2021, 7:32 PM

#

Fantastic - thanks!

distant raven Sep 26, 2021, 7:33 PM

#

📎 Adafruit-qt-py.lbr

#

there ya go

#

should be perfect

#

Screen_Shot_2021-09-26_at_1.35.32_PM.png

#

the header holes might not be perfect but should be pretty close

vagrant pecan Sep 26, 2021, 7:38 PM

#

ah nice - the one i was using didnt have header holes

#

but I only want those for alignment really 🙂

distant raven Sep 26, 2021, 7:38 PM

#

🙂

#

should do fine then

#

the extra long pads are so you can do the soldering with an iron

vagrant pecan Sep 26, 2021, 7:40 PM

#

yup

#

great stuff. thx!

limpid nest Sep 26, 2021, 7:44 PM

#

Is it permissible to ping ElectronicHarry if I'm continuing a discussion we had here yesterday?

distant raven Sep 26, 2021, 7:45 PM

#

Yeah, that’s permissible

limpid nest Sep 26, 2021, 7:46 PM

#

@heavy jasper I have a number of 1N4148 diodes, are those acceptable? The radioshack in my town doesn't open until 10 AM and is over an hour from my jobsite

#

regarding our conversation about my poor choice for driver for relays

#

I'll start designing a custom board tomorrow with the driver chips you recommended, but I need to get something running soon in order to justify my wage lol

#

and yeah, we still have a Radioshack. It rocks

limpid nest Sep 26, 2021, 8:56 PM

#

Related, how does one get an old fashioned EAGLE library, like you might get from a part generator, into Fusion360 EDA?

supple pollen Sep 26, 2021, 9:46 PM

#

Those might be fine for small relays, they're good for 100V and 150mA average current (peak is higher, which is good here).

limpid nest Sep 26, 2021, 9:48 PM

#

The switching signal is only 5V

#

and probably less than 20 mA

supple pollen Sep 26, 2021, 9:54 PM

#

I'm wondering what the characteristics are of the spike the relay coil produces when de-energized. However, 5V at 20mA doesn't seem like it would be a large relay with a lot of magnetic energy storage.

limpid nest Sep 26, 2021, 9:55 PM

#

It's a 20A Sparkfun relay

#

This project I'm refurbishing is 8+years old, I don't think SF sells the same relay anymore unfortunately

supple pollen Sep 26, 2021, 9:56 PM

#

That's annoying. I normally use ordinary power rectifier diodes (like the ubiquitous 1N400X series) for that duty. There aren't any lying around in your junk box?

limpid nest Sep 26, 2021, 9:57 PM

#

No unfortunately

#

I can order some, but I want to get some testing done this week and do one big order on friday

heavy jasper Sep 26, 2021, 9:57 PM

#

Nominal coil current appears to be 185mA.

supple pollen Sep 26, 2021, 9:57 PM

#

I suspect you can get away with using the signal diodes, they're reasonably robust.

heavy jasper Sep 26, 2021, 9:57 PM

#

at least per http://cdn.sparkfun.com/datasheets/Components/General/Relay.JQX-15F.pdf

limpid nest Sep 26, 2021, 9:58 PM

#

So I need beefier diodes? Unless the relay boards already have diodes?

heavy jasper Sep 26, 2021, 9:58 PM

#

The signal diodes are probably fine (but less so if you are PWMing the enable line, so be careful there!)

#

Also - this seems like it may be beyond the drive strength of your LED driver

limpid nest Sep 26, 2021, 9:59 PM

#

shoot

heavy jasper Sep 26, 2021, 9:59 PM

#

Yeah, current capability is 60mA per channel

limpid nest Sep 26, 2021, 9:59 PM

#

well, I guess I can start designing a board first thing tomorrow

heavy jasper Sep 26, 2021, 9:59 PM

#

Even the part I had suggested won't work well there, unfortunately

#

they're only rated for 100mA continuous current.

limpid nest Sep 26, 2021, 10:00 PM

#

Ah shoot, the previous design was normal shift registers triggering mosfets

heavy jasper Sep 26, 2021, 10:00 PM

#

That seems like it'd work just fine

limpid nest Sep 26, 2021, 10:00 PM

#

man I wasted a bunch of my employer's time pursuing this

#

But live and learn

supple pollen Sep 26, 2021, 10:01 PM

#

Some MOSFETs include an intentional or parasitic body diode which can serve (it's a different connection than across the coil, but still valid).

heavy jasper Sep 26, 2021, 10:01 PM

#

I think that diode is going in the wrong direction though?

#

(for a low-side switch, the coil voltage at the switching node swings initially to massively positive voltage)

supple pollen Sep 26, 2021, 10:03 PM

#

Oh, I must have had it backward, I thought the shut-off spike was negative.

limpid nest Sep 26, 2021, 10:03 PM

#

so would I need protection diodes for all my FETs?

heavy jasper Sep 26, 2021, 10:03 PM

#

It's a bit wonky: the collapsing current is a negative dI/dt, but in the reference frame of the inductor "positive" voltage is with the supply higher than the switched node, and positive current is supply flowing to switch node.

#

so the negative dI/dT makes a switched node much higher than the supply

supple pollen Sep 26, 2021, 10:04 PM

#

That does make sense, or flyback boost supplies wouldn't work, I suppose

#

I was thinking of the damper diode in television horizontal sweep circuits

limpid nest Sep 26, 2021, 10:08 PM

#

what would be good parameters for a MOSFET for this situation?

heavy jasper Sep 26, 2021, 10:09 PM

#

First option: Look at the ones that are currently in use and see if they're still available, or a recommended cross is available.

#

(Unless they're failing all over the place)

limpid nest Sep 26, 2021, 10:09 PM

#

ok, I don't know that the existing design was "good" however

heavy jasper Sep 26, 2021, 10:10 PM

#

It may or may not be, but if they're operating in your intended environment for a substantial period of time and aren't failing, that seems like a decent starting place.

limpid nest Sep 26, 2021, 10:11 PM

#

makes sense. speaking of intended environment lol, the electronics were all left outside exposed to ocean breezes.

#

for a good part of 3 presidential admins

heavy jasper Sep 26, 2021, 10:13 PM

#

oh jeez, salt spray / salt fog.

#

salt fog is one of the worst environmental operating tests for automotive modules

limpid nest Sep 26, 2021, 10:14 PM

#

Yeah I'm making IP rated enclosures/connections

#

the raspberry pi that runs this was screwed to piece of plywood

limpid nest Sep 26, 2021, 10:43 PM

#

For connectors like this, do the wires go in where the green lines are?

heavy jasper Sep 26, 2021, 11:31 PM

#

generally yes

#

The threads then pull the wire (via the two other metal bits) against the flat plate, clamping it in place

limpid nest Sep 26, 2021, 11:32 PM

#

that's what I figured from looking at it but wanted to be sure

#

So I need to control 12 outputs on 2 8bit shift registers to control 12 mosfets, to control 12 relays, how should the mosfets be configured? This is another thing I internalized wrong unfortunately

limpid nest Sep 26, 2021, 11:33 PM

#

heavy jasper The threads then pull the wire (via the two other metal bits) against the flat p...

appreciate the specificity!

#

would the signal from the 74HC595 go to the gate of the fet?

distant raven Sep 27, 2021, 8:40 PM

#

Changed the FPC connector and it worked! 😮‍💨

limpid nest Sep 27, 2021, 8:40 PM

#

wooooooo

distant raven Sep 27, 2021, 8:40 PM

#

I managed to find the same one Adafruit uses. Or pretty close anyway

worldly schooner Sep 27, 2021, 9:07 PM

#

Beautiful. Glad our efforts weren't wasted LOL

#

Looks really nice! Any plans to sell?

distant raven Sep 27, 2021, 9:13 PM

#

They’re actually for Nick Ruffilo for his Mad Eye Moody Eye cosplay prop 🙂

limpid nest Sep 27, 2021, 9:14 PM

#

read that as Mark Ruffalo and thought the eye should be greener

distant raven Sep 27, 2021, 9:22 PM

#

Lol

brisk hearth Sep 28, 2021, 4:45 AM

#

limpid nest read that as Mark Ruffalo and thought the eye should be greener

https://tenor.com/view/hulk-smile-banner-smiling-gif-7325607

Tenor

broken heart Sep 29, 2021, 2:07 AM

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I am trying to make a circuit diagram with eagle cad, does anyone have some knowledge of this software so I can ask a couple questions?

limpid nest Sep 29, 2021, 2:10 AM

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ask away! My eagle license expired and I'm on a home license of F360 EDA but I know a bit

broken heart Sep 29, 2021, 2:13 AM

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I just want to make a somewhat basic schematic with an arduino, some bipolar stepper motors with tb6560 controllers and some optic endstops

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I think I downloaded a tb6560 library because it didnt seem to be in there

limpid nest Sep 29, 2021, 2:13 AM

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just the schematic? No board?

broken heart Sep 29, 2021, 2:13 AM

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but since I havent really used the software

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yes just schematic

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is for a graduation project and I need a circuit schematic, It already works in real life haha but I need the schematic for documentation

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I dont know how to place the tb6560

limpid nest Sep 29, 2021, 2:15 AM

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Haha I got you. Well, EAGLE may not actually be the best tool for the job. You can definitely do it in EAGLE but a schematic may be faster in something like LucidCharts

broken heart Sep 29, 2021, 2:16 AM

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Oh I downloaded eagle because I just googled and some people seemed to say eagle could work

limpid nest Sep 29, 2021, 2:16 AM

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well maybe not that much faster, but a bit. As long as you're OK with your parts not looking like the parts, then EAGLE is fine

broken heart Sep 29, 2021, 2:16 AM

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if that is better I am willing to try

limpid nest Sep 29, 2021, 2:16 AM

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Let's see what we can do in EAGLE. Did you download any libraries with Arduinos in them?

broken heart Sep 29, 2021, 2:17 AM

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If they look like the parts I think it may be nice honestly

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not yet arduino

limpid nest Sep 29, 2021, 2:17 AM

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OK that's where EAGLE falls down a bit for doing stuff that is gonna be read by non engineers or non electrical people. Parts are usually just boxes with leads coming out of them, and they don't look very appealing.

broken heart Sep 29, 2021, 2:18 AM

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well I am a mechatronics almost engineer

limpid nest Sep 29, 2021, 2:18 AM

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congrats!

broken heart Sep 29, 2021, 2:18 AM

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and it is for my graduation project

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thanks a lot

limpid nest Sep 29, 2021, 2:18 AM

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I didn't mean you! I meant your audience

broken heart Sep 29, 2021, 2:19 AM

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limpid nest OK that's where EAGLE falls down a bit for doing stuff that is gonna be read by...

so that might not be a problem really

limpid nest Sep 29, 2021, 2:19 AM

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great!

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Check these out http://eagle.autodesk.com/eagle/libraries?button=&q[s]=uploaded_at+asc&q[title_or_author_or_description_cont]=arduino

broken heart Sep 29, 2021, 2:21 AM

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ok I got it

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I am in add part

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ill check which one is a uno

limpid nest Sep 29, 2021, 2:22 AM

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Did the libraries populate automatically? When I had eagle I had to add them myself

broken heart Sep 29, 2021, 2:24 AM

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i put them into the folder then i went into library manager and added them

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I had already added one for the tb6560

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but i seem to be unable to find that one in the add part

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I lied, it is there

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limpid nest Sep 29, 2021, 2:29 AM

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sweet! you can also get power signals from the add part, like 3v3,5V,and GND

broken heart Sep 29, 2021, 2:42 AM

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great great thank you so much! I'll try to go as far as I can from now on, do you mind if I add you in case I happen to have a random question later?

limpid nest Sep 29, 2021, 2:43 AM

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broken heart great great thank you so much! I'll try to go as far as I can from now on, do yo...

Sure! But you'd have good luck posting here as well, lots of knowledgeable folks

broken heart Sep 29, 2021, 2:44 AM

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alright, I am glad someone recommended this place in case I have a question

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thank you so much again 🙂

limpid nest Sep 29, 2021, 2:47 AM

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of course! good luck with your project

exotic tapir Sep 29, 2021, 8:09 AM

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What is best beginner friendly software for pcb designing

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I am absolute noob

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can anyone suggest a good software to get started with it

worldly schooner Sep 29, 2021, 11:28 AM

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exotic tapir What is best beginner friendly software for pcb designing

Kicad is the gold standard, but I find EasyEDA slightly easier to use for quick schematics. I think Fritzing is also a popular option that adafruit has a guide or two for.

exotic tapir Sep 29, 2021, 11:29 AM

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Thank you for your suggestion

worldly schooner Sep 29, 2021, 11:29 AM

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Make a Custom PCB with Fritzing | DIY Pico Mechanical Keyboard with Fritzing and CircuitPython | Adafruit Learning System

https://learn.adafruit.com/diy-pico-mechanical-keyboard-with-fritzing-circuitpython/make-a-custom-pcb-with-fritzing

Adafruit Learning System

DIY Pico Mechanical Keyboard with Fritzing and CircuitPython

Build your own custom mech keyboard that runs CircuitPython on the Raspberry Pi Pico RP2040

tough matrix Sep 29, 2021, 1:01 PM

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I am looking at one of TI datasheets and it seems there is an error there. Can someone confirm that?
Namely, the datasheet is https://www.ti.com/lit/ds/symlink/tmag5111.pdf
It is a dual channel Hall effect sensor.
The first page says that the outputs are open-drain, which I always took to mean that they are connected to ground when activated and left hi-z otherwise, so they require pull-up resistors.
Yet layout example on page 33 shows pull-down resistors to the ground.
Do you think it is a typo or am I misunderstanding something?

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distant raven Sep 29, 2021, 1:03 PM

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If it’s open drain, I thought that meant it needed to be tied to ground if it’s an output. I could be wrong though

tough matrix Sep 29, 2021, 1:04 PM

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my understanding was based on https://forum.digikey.com/t/what-does-open-drain-mean/716

distant raven Sep 29, 2021, 2:08 PM

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I think there is something fundamentally missing from the data sheet or an error like you suggested

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Maybe reach out to TI’s applications engineers?

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Looks like if you tie the open drain to ground it helps with thermal conductance

silk lark Sep 29, 2021, 2:45 PM

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open drain only means it's high-z when not active, it can be active-low or active-high still

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but I think in this case the resistors symbolize the load that you put on those pins

tough matrix Sep 29, 2021, 3:54 PM

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In this case, functional block diagram does suggest that it is active-low:

supple pollen Sep 29, 2021, 5:29 PM

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Presumably the trace angles up under the chip to Vcc, and is just mislabeled as "GND" on the right.

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I tried looking at the evaluation board, and it shows the resistors connected to Vcc, which is a copper pour on the component layer (ground goes to a via).

tough matrix Sep 29, 2021, 5:37 PM

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makes sense
I didn't think to look at the evaluation board - thanks!

limpid nest Sep 29, 2021, 6:04 PM

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I have 12 Mosfets in 3 different models (IRF510,IRF640N,IRF740), my local radioshack didn't have 12 of the same model. All of these seem suitable for switching 5V/180mA max, is that right?

limpid nest Sep 29, 2021, 8:13 PM

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The default symbol for +3.3V seems to have changed between EAGLE and Fusion360. This is just a normal power supply symbol still, right?

narrow shadow Sep 29, 2021, 8:57 PM

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Is it better to get started with PCB Design with something like EasyEDA? Or is it better to watch youtube videos about Altium tutorials?

limpid nest Sep 29, 2021, 8:58 PM

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narrow shadow Is it better to get started with PCB Design with something like EasyEDA? Or is i...

If you are considering a free program, KiCAD is a really good choice with lots of people using it and making vids

narrow shadow Sep 29, 2021, 8:58 PM

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limpid nest If you are considering a free program, KiCAD is a really good choice with lots o...

I'll look into that. I think my university has free Altium licenses for students though.

limpid nest Sep 29, 2021, 8:58 PM

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Ahh

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The trap there is the one I fell into, I only know how to use EAGLE because that's what my school offered

narrow shadow Sep 29, 2021, 8:59 PM

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That happened to me where my high school only taught modeling with Autodesk Inventor

worldly schooner Sep 29, 2021, 9:00 PM

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narrow shadow Is it better to get started with PCB Design with something like EasyEDA? Or is i...

Depends on your end goal? Altium is a great tool to learn for anyone looking to do it for a living. If you're not likely to design boards as a profession, KiCAD and EAGLE are more than sufficient.

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Going from Altium to the free stuff is usually easier than the other way around, though, so if your University is offering you Altium, take it and run with it.

narrow shadow Sep 29, 2021, 9:01 PM

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I would potentially want to use it to design basic to intermediate custom boards for the solar car club I'm in at my university.

limpid nest Sep 29, 2021, 9:02 PM

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altium sounds great then

narrow shadow Sep 29, 2021, 9:04 PM

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Sounds good! Thank you all for the advice!

limpid nest Sep 29, 2021, 9:04 PM

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good luck in school!

worldly schooner Sep 29, 2021, 9:05 PM

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If you're the type of person to be fairly proficient with most software you pick up, you probably don't have to worry about being locked into one over the other. Altium is powerful and has a lot of professional features, but you should be pretty free to experiment with anything once you're proficient in the underlying principles of schematic and board design.

limpid nest Sep 29, 2021, 9:06 PM

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do F360 files have identifying information in them? I'd like to get feedback on something at some point but don't want to doxx myself if I can avoid it. I know that EAGLE files were bare of ID info

bright thistle Sep 29, 2021, 10:08 PM

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uhmmm... despite being shipped later, the components for my pcb are already in, while the PCBs themselves are still MIA as of today...
should've chose tracked mail :/

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like, bits arrived some 2½ weeks ago

long wraith Sep 29, 2021, 11:30 PM

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I like surprises

bright thistle Sep 30, 2021, 1:24 AM

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long wraith I like surprises

Usually, me too.

But ~€40 down the gutter, should the parcel be lost? Not a pleasant one.

long wraith Sep 30, 2021, 1:24 AM

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Oof... yeah, I don't like that kind of surprise

supple pollen Sep 30, 2021, 1:49 AM

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I had a €75 package vanish after arriving in the United States. Happily, the seller sent a replacement.

empty hollow Sep 30, 2021, 8:55 AM

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Question, what is the best way to find high quality libraries for Eagle that include 3d models as well. I recently designed a pcb and the footprint for some components (cp2102, nfets, lm75a etc) were not the best and didnt have silk screen on the correct layer. Neither did they have 3d models.

bright thistle Sep 30, 2021, 11:51 AM

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empty hollow Question, what is the best way to find high quality libraries for Eagle that inc...

~~Did you try the kicad git repo?~~

Derrrrp, didn't read Eagle 😅

distant raven Sep 30, 2021, 12:23 PM

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empty hollow Question, what is the best way to find high quality libraries for Eagle that inc...

There is a 3D package generator built in to eagle you can use. It will actually make a footprint for you too if you put in the parameters from the data sheet

limpid nest Sep 30, 2021, 4:08 PM

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can F360 EDA models be opened in EAGLE?

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I'm a little confused by F360 EDA's part making process. I made a symbol, I made a footprint, and I added the footprint to the device, but I can't see how to add the symbol and connect pins

#

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Oops I goofed it's right there, need my coffee

limpid nest Sep 30, 2021, 5:52 PM

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I'm getting this error, but when I go to the grid settings I see what is expected

#

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~~well manually turning the grid on fixed it, in case anyone has this issue~~

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for some reason the grid in my PCB was affecting my schematic

smoky mica Oct 1, 2021, 12:16 AM

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so I was wondering, is there a recommended limit on how many pull-up resistors should be on an i2c bus? My design has 3 chips, each with a 10k resistor on each line.

limpid nest Oct 1, 2021, 12:16 AM

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I'd change your username to be in this discord, FYI

smoky mica Oct 1, 2021, 12:17 AM

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yeah lol

limpid nest Oct 1, 2021, 12:17 AM

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The total bus resistance can't be below a certain threshold, do you know how to calculate equivalent parallel resistances?

smoky mica Oct 1, 2021, 12:20 AM

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https://tenor.com/view/cat-what-que-recalculando-loading-gif-19097337

Tenor

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no

limpid nest Oct 1, 2021, 12:21 AM

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the total line resistance for the SDA or SCL lines can be calculated with

(1/R_TOTAL) = sum((1/R_N))

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so for your case it would be

(1/R_TOTAL) = (1/10,000) + (1/10000) + (1/10000) = 10000/3. It's a neat trick when all your parallel resistances have the same value, you can just divide one resistance value by the number of resistors (in this case 3 per data line)

smoky mica Oct 1, 2021, 12:23 AM

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nice

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ty

limpid nest Oct 1, 2021, 12:24 AM

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sure thing! Thanks for taking the time to change your username, wouldn't want you to run afoul of the mods

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we're generally G rated here, PG very occaisonally

smoky mica Oct 1, 2021, 12:24 AM

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yeah, i kinda forget some servers have tighter restrictions regarding swearing

limpid nest Oct 1, 2021, 12:24 AM

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it's all good 🙂

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Also your bus resistance should be fine at 3.333k

limpid nest Oct 1, 2021, 2:23 PM

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I was hoping to get a board review if anyone has time, can I upload Fusion360 Schematic/PCB without uploading personal information? I know EAGLE files were just text devoid of personal info.

worldly schooner Oct 1, 2021, 2:26 PM

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For a quick pass, screenshots usually suffice. If you want a detailed review, people have uploaded and downloaded schematics and board files in the past. Takes a bit longer, but someone usually finds time to look at it eventually.

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I don't know specifically about F360 files though, never really used them personally for electronics yet...

limpid nest Oct 1, 2021, 3:34 PM

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ok let me get some screenshots first

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Schematic screenshot 1:

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Screenshot 2

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Board shot:

limpid nest Oct 1, 2021, 3:54 PM

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I'm also trying to find a micro-usb version of this connector, or similar but I seem to be filtering wrong (https://www.digikey.com/en/products/filter/usb-dvi-hdmi-connectors/312?s=N4IgjCBcoEwBxVAYygMwIYBsDOBTANCAPZQDaIALGHFTCALqEAOALlCAMosBOAlgHYBzEAF9CYAJxwJiECkgYcBYmRAAGBszaROPAcLEgAtHWhyoPAK7KSkcgFYGIw6fIAjIum4ATAAQBbIkt%2BFgDeJG4iX0tsNycgA)

Connectors, Interconnects | USB, DVI, HDMI Connectors | DigiKey

Connectors, Interconnects - USB, DVI, HDMI Connectors are in stock at Digikey. Order Now! Connectors, Interconnects ship same day

worldly schooner Oct 1, 2021, 4:03 PM

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limpid nest I'm also trying to find a micro-usb version of this connector, or similar but I ...

That would be a panel-mount connector, not a board mount.

limpid nest Oct 1, 2021, 4:04 PM

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Yeah, I don't see a panel mount option

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I was considering making a board that just plugs into this https://www.adafruit.com/product/4213?gclid=CjwKCAjw49qKBhAoEiwAHQVTo4xam_J_zlJnyCpQwfHeG6CnumcXLky3nsrhQpRf4bOjftL0TSoklhoC-CkQAvD_BwE

Micro USB B Jack to USB A Plug Round Panel Mount Adapter

If you need to add a panel-mount connection but don't have the time or ability to cut a custom oval or square hole, this Micro USB B Round Panel Mount Plug is the easiest and ...

worldly schooner Oct 1, 2021, 4:06 PM

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Does it have to be sealed?

limpid nest Oct 1, 2021, 4:06 PM

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it would be best

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The environment is near the ocean, lots of fog

worldly schooner Oct 1, 2021, 4:10 PM

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https://www.digikey.com/en/products/detail/conxall-switchcraft/DCP-USBCB-F/5213110
They have some weird adapters like this? Can't find a micro to A atm...

limpid nest Oct 1, 2021, 4:14 PM

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So I need to breakout separate rails of 5V and GND from whatever adapter I use, so I was planning on making a miniboard to do that

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Can the 5V from the pi supply enough power to power a linear regulator that needs to provide 240 mA of 3v3?

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Ah, it's connected to mains power, so I just need to specify a beefy enough power unit!

limpid nest Oct 1, 2021, 4:52 PM

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Here's a small respin:

worldly schooner Oct 1, 2021, 5:40 PM

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Functionally looks fine, but if you have the time, I'd clean up this area for ease of production. You have a lot of space to work with, those traces don't need to be pressed up against each other that tightly...

limpid nest Oct 1, 2021, 5:41 PM

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good point

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thx

worldly schooner Oct 1, 2021, 5:41 PM

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If you utilize the space on the top right a bit more, you can pull those vias open and give your traces more clearance from each other.

limpid nest Oct 1, 2021, 5:41 PM

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ok I usually respin a board 2-3 times before I order so I'll def address that

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although that seems to require making the schematic again, because it seems in F360 that copying a schematic creates a schematic that is either still linked to the first PCB or thinks it should be linked to a PCB already. Frustrating

worldly schooner Oct 1, 2021, 5:43 PM

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Otherwise, it's a fairly simple interface board so if your prototype circuit works, the only other things to work on would be primarily cosmetic in nature.

limpid nest Oct 1, 2021, 5:44 PM

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My only concern was I'm using SMD component versions of the DIP 74HC595s I used in my Breadboard. I think they are pin compatible from reading the datasheets

worldly schooner Oct 1, 2021, 5:44 PM

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These are all low-speed signals so you should have plenty of freedom to arrange the traces and make the silkscreen look nice.

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The SMD components will usually have their own pinout diagrams, so it's best to cross-check the datasheet.

limpid nest Oct 1, 2021, 5:45 PM

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I did, I'm going to do so again to be safe

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I'm trying to find an at least IP66 rated, hopefully IP67 rated power connector for my enclosure, what is a good first category in digikey?

median wind Oct 1, 2021, 6:05 PM

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Just kinda asking ahead of time. I'll be having to work with circuitmaker, and wanted to know if this would be the place to ask about doubts I have

limpid nest Oct 1, 2021, 6:06 PM

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I don't know that program in particular but if it's EDA related, this is a fine place

median wind Oct 1, 2021, 6:06 PM

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we're working with this beauty 😆

limpid nest Oct 1, 2021, 6:07 PM

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looks like old software, hopefully that means it doesn't have a ton of bugs lol!

median wind Oct 1, 2021, 6:09 PM

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I think teacher shared this one because it's tiny, as internet issues are very common here. it's a lot of software for a 3MB program

limpid nest Oct 1, 2021, 6:10 PM

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Ahhh very cool!

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Nice teacher. I can't guarantee you'll find someone who's used it here, but who knows

median wind Oct 1, 2021, 6:12 PM

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circuitmaker still has software releases to this day... hopefully there hasn't been that many changes functionality wise. I'll also try and get a newer version when I can just in case. Anyway, I'll probably be back when I have some component questions 👋

tender cedar Oct 1, 2021, 8:09 PM

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I’m trying to use ATtiny85 as an I2C peripheral on custom board driven by an rp2040 feather. I have it set up so that the feather can boot as an AVR programmer with buffer gates to connect the RP2040s SCK to SCL, and MOSI to SDA, but I don’t know whether I need to protect the other I2C peripherals on the bus from the ‘rogue’ AVR ISP signals while the I2C bus is being repurposed. Would it be sufficient to just put a buffer gate on the SCL clock line between the Tiny85 and the rest of the downstream I2C bus so I can just set it to high impedance during ISP programming? Presumably the other I2C peripherals will just ignore the SDA line if ‘their’ SCL stays pulled high? It works fine on a breadboard without anything isolating the other peripherals from the bus during programming but i don’t trust it.

limpid nest Oct 1, 2021, 9:31 PM

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Is X7R a good choice for output/input caps on this chip? https://www.digikey.com/en/products/detail/onsemi/NCP1117DT33T5G/921285

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And can I get away with 10V rating on both the 3.3V output and 5V input?

supple pollen Oct 1, 2021, 10:12 PM

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X7R should be fine, the 10V rating will give a good leeway, which is useful, as that dielectric loses some capacitance with voltage, so the headroom will be beneficial.

limpid nest Oct 1, 2021, 10:13 PM

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That was my understanding, I usually try for 2.5x rating

limpid nest Oct 1, 2021, 10:22 PM

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supple pollen X7R should be fine, the 10V rating will give a good leeway, which is useful, as ...

Did we discuss solid state relays yesterday?

supple pollen Oct 1, 2021, 10:24 PM

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Yeah, I think so?

limpid nest Oct 1, 2021, 10:28 PM

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I was considering this relay (https://www.digikey.com/en/products/detail/sensata-crydom/CL240D05R/2330429), but they don't have enough in stock. Does this one seem like it would do the same job? Switching mains power using 3.3V from a 74HC595
https://www.digikey.com/en/products/detail/sensata-crydom/D2425/139477

D2425 Sensata-Crydom | Relays | DigiKey

Order today, ships today. D2425 – Solid State SPST-NO (1 Form A) Hockey Puck from Sensata-Crydom. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

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Also needs to be at the end of a twisted pair cable that is 30 feet long, should I employ boosting of some kind?

supple pollen Oct 1, 2021, 10:30 PM

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That seems like it should work. Since it's basically a current loop connection, the long cable shouldn't be a problem. My only worry is if the '595 can drive all the loads at once, if they draw the worst case current.

limpid nest Oct 1, 2021, 10:31 PM

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yeah that was a concern I have as well

supple pollen Oct 1, 2021, 10:31 PM

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You could use a high power '595 like this one: https://www.adafruit.com/product/457

TPIC6B595 High Power Shift Register

Add a bunch of high-power outputs to a microcontroller system with chainable shift registers. These chips take a serial input (SPI) of 1 byte (8 bits) and then output those digital bits onto ...

limpid nest Oct 1, 2021, 10:31 PM

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I thought I could get 20 mA out of each pin when all were on at the same time

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Does that chip presumably work with the 74HC595 CP lib?

supple pollen Oct 1, 2021, 10:31 PM

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If so, then you should be fine, that SSR specifies a worst case draw of 12mA

limpid nest Oct 1, 2021, 10:31 PM

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let me read the datasheet for the specific spin of '595 I'm considering

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https://www.ti.com/lit/ds/scls040g/scls040g.pdf

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Ah shoot, it says +/- 6mA ?

supple pollen Oct 1, 2021, 10:33 PM

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Yeah, that's in the "might work" realm.

limpid nest Oct 1, 2021, 10:34 PM

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Seems to actually be on firmer ground

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Oh oops that's input current

supple pollen Oct 1, 2021, 10:34 PM

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That's the protection diode clamp current...

limpid nest Oct 1, 2021, 10:37 PM

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Is this more relevant?

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I don't know if that's per pin or not

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Adafruit page for the 74HC595 seems to say they are good for 20 mA per pin

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Ah but the datasheet says that the max continuous current thru VCC is 70 mA?

supple pollen Oct 2, 2021, 1:20 AM

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That 35mA is the absolute maximum, not intended for ongoing use. The 70mA is the absolute maximum total chip current draw.

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This is the relevant section. It doesn't directly state output current capability, but the conditions for the output voltage are given with a 6mA load for a supply voltage of 4.5V and with a 7.8mA load for a supply voltage of 6V.

limpid nest Oct 2, 2021, 1:28 AM

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ahhh ok, I was trying to make sense of that table

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I think I'm just going to switch mosfets using the 74HC595, so I don't have to worry about power or CP libs

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thank you!

supple pollen Oct 2, 2021, 1:43 AM

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That's a good approach. Note that if you're switching MOSFETs with only 3.3V, you'll need some that get solidly to low resistance on 3.3V. Don't pay too much attention to "threshold voltage", that's just the voltage at which they conduct a detectable amount of current: you'll want MOSFETs that are solidly "on" at 3.3V.

limpid nest Oct 2, 2021, 1:43 AM

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let me pull up a saturation curve

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I also need to figure out whether I am hi side switching or low

supple pollen Oct 2, 2021, 1:46 AM

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For example, this popular MOSFET specifies a typical threshold voltage of only 1.8V, but this resistance graph soars near vertical with 4V

limpid nest Oct 2, 2021, 1:48 AM

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So should I pick all the low threshold ones, and then examine the datasheets for a truly low threshold one?

supple pollen Oct 2, 2021, 1:48 AM

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This graph implies you can pull 5A through it with only 3V on the gate, but it would get pretty warm if you did so for long (that ≤60µs note is there for a reason)

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Yes, you've got the right idea. Sometimes you have to look at the curves, but often the front page will have useful notes like "Very Low RDS(on) at 4.5V Vgs" or "8.7mΩ@Vgs = 10V".

limpid nest Oct 2, 2021, 1:50 AM

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what does Rdson signify?

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Also I want V_Gate_to_Source_Threshold right?

supple pollen Oct 2, 2021, 1:52 AM

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Rds(on) is the resistance (R) from drain (D) to source (S) with the transistor on.

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Yes, you'll want low threshold devices, I'm just pointing out that they're not really "on" at the threshold voltage, that's just the voltage at which they begin to turn on.

limpid nest Oct 2, 2021, 1:53 AM

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I see thanks, I see that I have some datasheetmining to do

empty hollow Oct 2, 2021, 3:52 AM

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should I place vias in thermal pad of the cp2102 chip to avoid solder overflow?

#

limpid nest Oct 2, 2021, 3:55 AM

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only if your manufacturer can do that

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not all of them can

empty hollow Oct 2, 2021, 11:47 AM

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Is there a list of common smd components for hobby and prototyping use. like all the jelly bean stuff. I want to build an smd component stash so that I can prototype more quickly but am finding it hard to find jelly bean mosfets, transistor, diodes, common resistors and caps, useful ic's etc.

twilit aurora Oct 2, 2021, 12:43 PM

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Is there any stemma qt module layout for kicad out there? I want the same pcb size and connector positions as for example on this board: https://learn.adafruit.com/mpu6050-6-dof-accelerometer-and-gyro

Sadly afaik Adafruit "only" provides the files for Eagle, but not for KiCAD

Adafruit Learning System

MPU6050 6-DoF Accelerometer and Gyro

Tilting? Spinning? We've got this, IMU know it!

supple pollen Oct 2, 2021, 1:15 PM

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I think KiCAD can read Eagle files, or there's a translator out there you can use.

supple pollen Oct 2, 2021, 1:16 PM

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empty hollow Is there a list of common smd components for hobby and prototyping use. like all...

You could look at the AdaFruit Eagle parts libraries for a start (or the parts on boards that appeal to you). Another possibility is looking for SMD equivalents to the common through-hole parts listed here: http://www.ladyada.net/wiki/partfinder

empty hollow Oct 2, 2021, 1:16 PM

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Thanks

supple pollen Oct 2, 2021, 1:16 PM

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For resistors and capacitors, there's this: https://www.adafruit.com/product/442

SMT 0603 Resistor and Capacitor Book - 3725 pieces

Always have the right SMT components at your hand with this awesome 0603 Resistor and Capacitor book set! This book has nice translucent pages filled with cut tape 0603 SMT components, ...

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For transistors, there's the MMBT2222 (basically a surface mount equivalent of a 2N2222) for bipolar and 2N7002 (basically a surface mount equivalent of a 2N7000) for MOSFET

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For diodes, there's a surface mount version of the common 1N4148, and a Schottky one that's on a lot of AdaFruit boards (and, of course, some LEDs)

rocky quest Oct 3, 2021, 3:53 AM

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twilit aurora Is there any stemma qt module layout for kicad out there? I want the same pcb si...

they have images as well

twilit aurora Oct 3, 2021, 8:18 AM

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rocky quest they have images as well

I importef it into kicad. Didn‘t know that this was possible, thanks

limpid nest Oct 4, 2021, 4:47 PM

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There are two application circuits for this part ( https://ww1.microchip.com/downloads/en/DeviceDoc/21373C.pdf), one showing only an output cap, and one showing an input and output with these guidelines. I'm not certain whether I meet them, but want to be safe, is it reasonable to just include an input cap to be safe or could that be a problem?

supple pollen Oct 4, 2021, 6:07 PM

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An input capacitor is generally a good idea with most LDOs, but I'm not familiar with this chip in particular. I pretty much always include an input cap in my designs.

silk lark Oct 4, 2021, 6:07 PM

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you can always leave the footprint unpopulated if it works without it

limpid nest Oct 4, 2021, 6:07 PM

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ah both good points thank you

limpid nest Oct 4, 2021, 8:20 PM

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does anyone know how to renumber parts in Fusion 360 schematics/PCBs? I found a script online but it borked my board completely

limpid nest Oct 4, 2021, 8:59 PM

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Also when is the autorouter permissible?

unreal flax Oct 4, 2021, 9:06 PM

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When you need to deliver a board NOW, you have a fairly low-density design, and your name won't be associated with the mess the autorouter will create. 😅

limpid nest Oct 4, 2021, 9:07 PM

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lolololol

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OK, I was gonna try to autoroute it and see if it looked ok, fine to post here?

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I have 4 ICs, a total of 28 positions worth of terminal blocks, and a pi header using only power, SPI, and two GPIO pins

unreal flax Oct 4, 2021, 9:08 PM

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Sure, it's fine to post it. That might be low-density enough to work okay, although it's also simple enough to hand-route pretty fast.

limpid nest Oct 4, 2021, 9:09 PM

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I usually have to do 3 or 4 routing schema before I'm happy with it, so it would be nice it autorouter could do it

limpid nest Oct 4, 2021, 9:14 PM

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unreal flax When you need to deliver a board NOW, you have a fairly low-density design, and ...

You weren't kidding. I am pretty sure I've had a nightmare about this creature

supple pollen Oct 4, 2021, 9:22 PM

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I've seen some autorouter shenanigans, but that's wild. I would do the chip positioning differently, so you'd get lots of parallel tracks.

limpid nest Oct 4, 2021, 9:24 PM

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rotate all the chips?

supple pollen Oct 4, 2021, 9:32 PM

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I'd put the shift registers end to end, with the drivers next to them.

limpid nest Oct 4, 2021, 9:32 PM

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short end to short end?

supple pollen Oct 4, 2021, 9:33 PM

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Yes, basically having the broad sides of the shift registers face the broad sides of the drivers.

limpid nest Oct 4, 2021, 9:33 PM

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like this?

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but perhaps more spacing?

supple pollen Oct 4, 2021, 9:35 PM

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Yeah: You may have to spin them around, but something like that should let you have a bunch of short parallel traces (this is also what I meant by choosing circuits for routability: arrange to have the inputs on the drivers line up with the outputs on the shift registers)

limpid nest Oct 4, 2021, 9:36 PM

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makes sense, thanks

supple pollen Oct 4, 2021, 9:36 PM

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You could also see if you can find the drivers in the same package, that looks like SO-16, where you can run traces between the pins, which will likely come in handy.

limpid nest Oct 4, 2021, 9:38 PM

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In digikey

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s

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Oops one sec

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In digikey it looks like the driver chip only comes in the package above

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although the fusion 360 part package from Digikey doesn't really look like the part on the page

limpid nest Oct 4, 2021, 9:45 PM

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supple pollen You could also see if you can find the drivers in the same package, that looks l...

Weirdness, in the filter view, Digikey shows 6601 SN74LS07DBRs, but when you open the product page, none are in stock

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Mouser seems to have it, and their picture matches the footprint

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https://www.mouser.com/ProductDetail/Texas-Instruments/SN74LS07DBRG4?qs=SL3LIuy2dWxn7w3RmwRLvQ%3D%3D This seems to be the same chip

Mouser Electronics

SN74LS07DBRG4 Texas Instruments | Mouser

supple pollen Oct 4, 2021, 9:58 PM

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Ah, they're out of the -D and -DR packages which are SOIC-14, which might be easier to route

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But these are available: https://www.digikey.com/en/products/detail/texas-instruments/SN7407NSR/1575132

SN7407NSR Texas Instruments | Integrated Circuits (ICs) | DigiKey

Order today, ships today. SN7407NSR – Buffer, Non-Inverting 6 Element 1 Bit per Element Open Collector Output 14-SO from Texas Instruments. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

limpid nest Oct 4, 2021, 10:01 PM

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Ah that would be much easier to route

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I wonder if DIgikey is aware that their footprint doesn't match the part picture

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for the out of stock version

supple pollen Oct 4, 2021, 10:16 PM

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You can always tell them. They do have a "Image is a representation only" note on their pictures.

limpid nest Oct 4, 2021, 10:16 PM

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ah good point

limpid nest Oct 4, 2021, 10:59 PM

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This looks like a much better autorouter output, I laid half the traces myself to give it a good jumping off point

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This is a little janky

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@unreal flax, if you have a moment, are these vias too close? closest distance is 60 mil

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unreal flax Oct 4, 2021, 11:13 PM

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It'll depend on the specs of your fab house, but that should be okay for most places.

limpid nest Oct 4, 2021, 11:13 PM

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I'm using JLC

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if that helps

unreal flax Oct 4, 2021, 11:14 PM

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I don't know what they do off the top of my head, but they should publish all the numbers, which you can put into the DRC settings to be sure.

limpid nest Oct 4, 2021, 11:14 PM

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ahh I'll have to figure out how to load DRCs into F360

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Hopefully JLC has included guidance

unreal flax Oct 4, 2021, 11:14 PM

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Should be pretty similar to Eagle, I'd expect.

limpid nest Oct 4, 2021, 11:14 PM

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I would hope so

limpid nest Oct 4, 2021, 11:18 PM

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unreal flax Should be pretty similar to Eagle, I'd expect.

This trace says it's .039...., that should be inches right?

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unreal flax Oct 4, 2021, 11:19 PM

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Yeah, that looks about right. About 1mm.

limpid nest Oct 4, 2021, 11:21 PM

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Ok, for calculating my minimum trace width I multiplied my worst case current draw by my number of current drawing elements and got .192A, it spits out a required width of 1.58 mil, that would be .00158 or similar from the trace width menu in F360?

unreal flax Oct 4, 2021, 11:22 PM

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Yep. The board house will probably have larger minimums than that.

limpid nest Oct 4, 2021, 11:22 PM

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I'm sort of leery of using anything smaller than .005

unreal flax Oct 4, 2021, 11:22 PM

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That's wise.

limpid nest Oct 4, 2021, 11:23 PM

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Looks like JLC's min is indeed 5 mil

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worth going to 10 mil to be safe?

unreal flax Oct 4, 2021, 11:23 PM

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Yeah, I tend to default to 10 unless I anticipate having some fine-pitch chips.

limpid nest Oct 4, 2021, 11:24 PM

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Ah gosh, all my autorouting was done in .006

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I do have a lot of connections, is it safe to use .006? I don't want to have to redo them

unreal flax Oct 4, 2021, 11:25 PM

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If JLC says 5 is fine, that's typically their "we guarantee this will work" number, so you don't have to have any margin on it if you don't want to. So feel free to stick with 6 if you like.

limpid nest Oct 4, 2021, 11:25 PM

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noiice! thanks

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Always appreciate the expert advice here

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Is there a charity you and @supple pollen like that I could make a small donation to?

unreal flax Oct 4, 2021, 11:26 PM

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Just pay it forward by helping other folks. 😁

limpid nest Oct 4, 2021, 11:27 PM

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haha ok!

twilit mango Oct 5, 2021, 4:14 PM

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@silk lark Hello! Are you around and up for being a second set of eyes on something? I'm making a Fritzing object and it has a lot of components. (Well not a ton, but more than usual.) Anyway, I want to make sure none are missing. So I would send you a screenshot of the thing and you would take a look to make sure there aren't any empty pads. I'm pretty sure there's not, but I have missed things before.

silk lark Oct 5, 2021, 4:15 PM

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sure, though I'm not an expert for the breadboard mode in fritzing, I mostly use it for PCBs

twilit mango Oct 5, 2021, 4:15 PM

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This is an SVG. I haven't even imported it into the Fritzing app yet.

silk lark Oct 5, 2021, 4:15 PM

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but I might catch somehting

twilit mango Oct 5, 2021, 4:15 PM

#

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Limor usually looks but she's super slammed today.

silk lark Oct 5, 2021, 4:17 PM

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are the Rt IO and CL pins also connectedable?

twilit mango Oct 5, 2021, 4:17 PM

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Yeah they will be.

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Like I said, it's not in Fritzing yet, it's only the image of the part.

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Those will be, and the colored dots on the JST connectors will be as well.

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I think that's it.

silk lark Oct 5, 2021, 4:17 PM

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yeah, looks good

twilit mango Oct 5, 2021, 4:18 PM

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Ok thank you!

silk lark Oct 5, 2021, 4:18 PM

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someone who knows the part might give better feedback

twilit mango Oct 5, 2021, 4:18 PM

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Yeah, agreed, but some feedback is better than no feedback, and that's the other option for most of today 🙂

silk lark Oct 5, 2021, 4:19 PM

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I can see two test points, but I assume those are fiducials for the PNP

twilit mango Oct 5, 2021, 4:19 PM

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Indeed they are

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The software that creates these things includes the fiducials.

silk lark Oct 5, 2021, 4:19 PM

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if you take aesthetic advice, I would make the PCB itself a bit brighter than 100% black, and the silkscreen a bit darker than 100% white, but that's me

twilit mango Oct 5, 2021, 4:20 PM

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Hmm, fair enough. I think that would involve a ton of manual work, or recompiling the software with updated numbers, which I have had to do once, but couldn't do again if I tried.

silk lark Oct 5, 2021, 4:20 PM

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yeah, not worth it probably

twilit mango Oct 5, 2021, 4:20 PM

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Thanks though! Appreciate it.

silk lark Oct 5, 2021, 4:21 PM

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just saying the contrast is very high here

twilit mango Oct 5, 2021, 4:21 PM

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Yeah. They used to be blue when we had the blue PCB house. But then we went with black, and that's what Limor asked for. So I went with it.

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Prototypes are still all kinds of colors, but most everything else is black PCB. Which isn't true black. But the Fritzing objects are.

silk lark Oct 5, 2021, 4:22 PM

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you know, even the shiny black pcbs are not Vanta Black black

twilit mango Oct 5, 2021, 4:22 PM

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Hah, right?

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Your PCB absorbs all light.

limpid nest Oct 5, 2021, 4:44 PM

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Is there a safeish way to test the mains current coming thru a relay like this? Can I just hook my multimeter in line with one of the hot wires?

clever shadow Oct 5, 2021, 5:27 PM

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If I'm simply using a MOSFET as a switch, can I mostly ignore the Safe operating area and just use the device maximum current/votlages as a guide? Eg Can the AO3400A be used to turn a 3A device on/off?

supple pollen Oct 5, 2021, 5:51 PM

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As long as you avoid having maximum current and voltage at the same time, and have sufficient heatsinking for the average dissipated power, you'll generally be okay.

limpid nest Oct 5, 2021, 6:45 PM

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Hoping for a second revision review, if anyone has time. Here's the schematic in 2 parts

#

#

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And the board in 2 parts

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supple pollen Oct 5, 2021, 6:56 PM

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That's a solid improvement on the previous version!

limpid nest Oct 5, 2021, 7:04 PM

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It's about 50% autorouter lol

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any glaring issues?

tough matrix Oct 5, 2021, 7:06 PM

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Some things looks strange, but it is probably of low-res rendering
can it output PDF?

limpid nest Oct 5, 2021, 7:09 PM

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Let me see

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heh, ran the PRINT command in P360 EDA and it's hung

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one moment

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I can print it as a PDF, but it's pretty small

tough matrix Oct 5, 2021, 7:13 PM

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well, PDF can be maginified indefinitely

limpid nest Oct 5, 2021, 7:13 PM

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Heres the board, you can zoom in on it

📎 12DaysV2.pdf

tough matrix Oct 5, 2021, 7:20 PM

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#

this looks unusual

limpid nest Oct 5, 2021, 7:21 PM

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I was getting and airwire there, so I created a new path to 3v3, let me see if it isn't needed

tough matrix Oct 5, 2021, 7:21 PM

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and this thin red line around U4 is not on copper layer, right?

limpid nest Oct 5, 2021, 7:22 PM

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No that's tKeepout I think

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It's hatched and looks like keepout

tough matrix Oct 5, 2021, 7:23 PM

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do you intend to print designators (U1,...) and part numbers (SN74...) on silkscreen?

limpid nest Oct 5, 2021, 7:23 PM

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Just the designators, haven't cleaned it up yet

limpid nest Oct 5, 2021, 7:23 PM

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tough matrix

Without that trace, there isn't a path to 3v3 for that pin

tough matrix Oct 5, 2021, 7:23 PM

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some of them are on top of SMD pads

limpid nest Oct 5, 2021, 7:24 PM

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yeah it's a mess atm

tough matrix Oct 5, 2021, 7:27 PM

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other that, seems fine to me

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you are using both 5V and 3.3V?

limpid nest Oct 5, 2021, 7:28 PM

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Yeah

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I'm told that the part that takes 3v3 signals to activate can run at 5V and be triggered by 3v3

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The open collector arrays

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*must take 5 volts

tough matrix Oct 5, 2021, 7:32 PM

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ok

limpid nest Oct 5, 2021, 7:33 PM

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Does that 3v3 trace you called out seem like a major concern?

tough matrix Oct 5, 2021, 7:35 PM

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I'd try and understand why the software complains about airwire even though it seems it is connected to the pour (I understand that the pour is 3.3V?)

limpid nest Oct 5, 2021, 7:36 PM

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yeah it is. I I think that that pad is completely surrounded by traces, blocking the actual 3v3 signal from reaching the pad

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Can anyone help me figure out what this circuit is trying to do? I'm in the enviable position of having no schematics or explanations. The IC is a ULN2803A. It doesn't SEEM to be functional at all. The circuit is just supposed to switch the relay

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I think the outputs of the darlington are tied to the terminal block not touching my thumb, and there's nothing tied into the outputs

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5v/gnd for the relay come in at the terminal block my thumb is on

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I think the array is vestigial and can be ignored

fervent lance Oct 5, 2021, 8:51 PM

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2803 completes the ground

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It doesn't source, it only sinks, current.

limpid nest Oct 5, 2021, 8:53 PM

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makes sense, but there's nothing sinking current into it

supple pollen Oct 5, 2021, 10:18 PM

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Presumably the relay coil is connected between a voltage supply and the 2803, so it sinks current through the coil to actuate the relay.

limpid nest Oct 5, 2021, 10:23 PM

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but there aren't any wires leading to the input to the 2803?

tough matrix Oct 5, 2021, 10:42 PM

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is it just me having problem when ordering assembly from JLCPCB - their preview commonly shows components slightly shifted?
(this is is using KiCad to export .pos file)

limpid nest Oct 5, 2021, 10:55 PM

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I've gotten feedback that their preview isn't 100% accurate for boards but I don't know about assembly.

tough matrix Oct 5, 2021, 11:00 PM

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I just can't figure out why... it is not that I got the sign wrong, or units wrong - it is a minor shift, like 2mm

unreal flax Oct 5, 2021, 11:15 PM

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tough matrix I just can't figure out why... it is not that I got the sign wrong, or units wro...

Any chance the library part doesn't have the coordinate origin at the chip centroid?

tough matrix Oct 5, 2021, 11:17 PM

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i could believe it for something complicated, but for 0603 smd resistor?

worldly schooner Oct 6, 2021, 1:25 PM

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If it's a couple of specific components, I would hope so. It's not like a computer algorithm really cares for the difference between a 100-pin IC and a SMD resistor, as long as the definitions are there.

tough matrix Oct 6, 2021, 2:20 PM

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well, in this one case it was for all components - including resistors.

worldly schooner Oct 6, 2021, 2:33 PM

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A fixed amount?

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Sounds less like a lib issue and more of a graphical one on their end....

tough matrix Oct 6, 2021, 2:46 PM

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maybe...

limpid nest Oct 6, 2021, 5:32 PM

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These relays seem equivalent for my purposes, switching mains power with 5V switching signal, can anyone see a relevant difference between the two? I sure can't
https://www.digikey.com/en/products/detail/sensata-crydom/CL240D10R/14799475

https://www.digikey.com/en/products/detail/sensata-crydom/CL240D10/2330435

I don't know what AC - zero cross means, but it seems the be the only difference. Only asking because they don't have enough stock of the CL240D10

CL240D10R Sensata-Crydom | Relays | DigiKey Marketplace

Order today, ships today. CL240D10R – Solid State SPST-NO (1 Form A) Hockey Puck from Sensata-Crydom. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

worldly schooner Oct 6, 2021, 5:55 PM

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limpid nest These relays seem equivalent for my purposes, switching mains power with 5V swit...

AC zero cross means even when you disengage the relay, the current continues to flow until the AC sinusoid reaches zero. These are commonly used for switching AC power because trying to open the circuit while the voltage isn't zero can potentially cause the extra energy to discharge in an undesirable way.

limpid nest Oct 6, 2021, 5:58 PM

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so I want zero cross?

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for safety?

worldly schooner Oct 6, 2021, 6:00 PM

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Depends where your mains go to. If you have a lot of sensitive AC components, zero cross is highly recommended. If you just have an AC/DC converter that's robust enough to casually brush off the inrush, it doesn't make a difference.

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Sometimes Zero-Cross is desired to be able to force a circuit open with a higher response time. It all depends on application.

limpid nest Oct 6, 2021, 6:01 PM

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It's 12 relays, mostly powering AC LED christmas lights but there are a few motor drivers with AC adapters powering the motors

worldly schooner Oct 6, 2021, 6:04 PM

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https://en.wikipedia.org/wiki/Zero_crossing_control

Zero crossing control

Zero crossing (or burst-firing) control is an approach for electrical control circuits that starts operation with the AC load voltage at close to 0 volts in the AC cycle. This is in relation to solid state relays, such as triacs and silicon controlled rectifiers. The purpose of the circuit is to start the triac conducting very near the time poi...

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For your application, it's neither necessary nor undesirable. Your devices might not be timed as strictly with a zero-cross, but if you can accept a max 10ms deviation on your timings, you can take the zero-cross.

limpid nest Oct 6, 2021, 6:07 PM

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so what's desirable about zero cross in my application? I'm reading the wiki now

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Would non-zero cross not have the 10 ms delay?

worldly schooner Oct 6, 2021, 6:09 PM

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It would, and I don't know what the effect of a current inrush would be for your lights, but I expect it to have virtually no effect on the motors.

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Actually, I'm pretty sure the lights won't care either, since LED dimmers use PWM.

limpid nest Oct 6, 2021, 6:10 PM

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hmm ok, I'll see if another supplier has the zero cross ones, 10ms isn't a big deal and I can account for it in my code if I need to

worldly schooner Oct 6, 2021, 6:11 PM

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You probably don't need zero-cross, since it sounds like it's just LEDs and AC/DC converters.

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It's not a fixed 10ms delay, either, since it has to do with how your timings correspond to the zero crosses in the AC source.

limpid nest Oct 6, 2021, 6:14 PM

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ok cool! Thanks as always

limpid nest Oct 6, 2021, 6:41 PM

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I'm making a breakout-for-a-breakout so that I can mount a sparkfun Breakout that doesn't have mounting holes. Here are the relevant dimensions from the SF part

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and my mounting board

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Anything look hinky at a first pass? I'm concerned that .15" isn't enough spacing

worldly schooner Oct 6, 2021, 6:47 PM

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Can't use a male and female header?

limpid nest Oct 6, 2021, 6:48 PM

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What's that?

worldly schooner Oct 6, 2021, 6:51 PM

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You know, header pins and female headers used to mount microcontrollers to other boards

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Oh, this is for panel mounting instead of board mounting

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NVM

limpid nest Oct 6, 2021, 6:52 PM

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Oh I thought you meant some product I'd never heard of XD

worldly schooner Oct 6, 2021, 6:53 PM

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No, 0.15 isn't enough to clear the edge of the board above.

limpid nest Oct 6, 2021, 6:53 PM

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.25?

worldly schooner Oct 6, 2021, 6:53 PM

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Depends on what you're putting in those holes.

limpid nest Oct 6, 2021, 6:54 PM

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just pin headers, I want to expose the all the pads on something that can be mounted to acrylic

worldly schooner Oct 6, 2021, 6:54 PM

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Assuming they're a 0.1" pitch header footprint, you want to clear the edge of the board by at least the header's width

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Oh, wait

limpid nest Oct 6, 2021, 6:55 PM

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and I have headers and calipers! I should have thought of this, but alas I have a cold and missed my morning caffeine. Or I'll blame that 😛

worldly schooner Oct 6, 2021, 6:55 PM

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.2" total is .1" on either side

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.25" should be fine

limpid nest Oct 6, 2021, 6:55 PM

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ok cool, just need to rearrange a bit

worldly schooner Oct 6, 2021, 6:56 PM

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.2" should work too, but 0.25 will give you a bit of clearance on those pins

limpid nest Oct 6, 2021, 6:56 PM

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clearance is good in this case, may need to do some fiddly soldering

worldly schooner Oct 6, 2021, 6:56 PM

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In any case, you should also consider what you plan to mate to the pin headers when you define clearances.

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For a standard female socket dupont, 0.05" from hole center to edge of board may be enough, but your sockets would rub right up against that board above it...

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For a board-mounted female header, you have to consider where on that board your sockets are as well.

limpid nest Oct 6, 2021, 7:00 PM

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I was planning on soldering the breakout male pins directly to the board I'm making, but I could probably get away with female headers, and it might be better

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although that would put the breakout board pretty hi up on the breakout-breakout

worldly schooner Oct 6, 2021, 7:05 PM

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Up to you. If you're only making one or two of these things, you don't have to consider manufacturability...

limpid nest Oct 6, 2021, 7:21 PM

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I'm making 3, and I'm gonna use a different chip for future designs most likely

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And I'm bringing the boards up myself so it's not too bad

limpid nest Oct 6, 2021, 8:33 PM

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when measuring mains current coming thru a relay with a clamp meter, should I be putting the clamp around just one of the wires, or both?

worldly schooner Oct 6, 2021, 8:54 PM

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https://www.fluke.com/en-us/learn/blog/clamps/how-to-measure-current

How to Measure Current with a Clamp Meter

Measuring ac current with a clamp meter’s jaws. Note: Current flowing in opposite directions cancels each other. If current is moving in opposite directions, place just one conductor within the clamp during measurement.

limpid nest Oct 6, 2021, 9:12 PM

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Ah fluke, always in my heart

twilit mango Oct 6, 2021, 9:15 PM

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Hey folks, need some quick help, if anyone's around.

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Is this called "voltage shifting"?

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I'm used to "level shifting" or "voltage regulators" but I'm not sure how to word this.

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I have to ask a question about it and don't want to look uninformed. Even though I clearly am. 🙄

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@silk lark Are you still around? Sorry for pinging again.

silk lark Oct 6, 2021, 9:19 PM

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sure, no problem

twilit mango Oct 6, 2021, 9:20 PM

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What do I call what's happening to the I2C pins in that screenshot?

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I can get more of the schematic if you need it. That seemed like the section I needed info about.

silk lark Oct 6, 2021, 9:20 PM

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yes, that is a logic level shifter

twilit mango Oct 6, 2021, 9:21 PM

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Ah. Ok, so I was mixing terminology there.

silk lark Oct 6, 2021, 9:21 PM

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it changes the voltage of the logic signal

twilit mango Oct 6, 2021, 9:21 PM

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Right right, ok.

silk lark Oct 6, 2021, 9:21 PM

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no, it is voltage shifting

twilit mango Oct 6, 2021, 9:21 PM

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Oh

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HEh

silk lark Oct 6, 2021, 9:21 PM

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logic level = voltage

twilit mango Oct 6, 2021, 9:21 PM

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Ah fair enough!

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Well, I guess pat on the back for me. I wasn't too far off.

silk lark Oct 6, 2021, 9:21 PM

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specifically, voltage of a logic signal, but still voltage

twilit mango Oct 6, 2021, 9:22 PM

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So "level shifted" is an accurate way to describe the pins on the other side of it?

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Oof, Discord isn't sending.

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There it goes.

silk lark Oct 6, 2021, 9:22 PM

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so "voltage shifting" is correct, "logic level shifting" is a little bit more precise

twilit mango Oct 6, 2021, 9:22 PM

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Ok, great. Thank you so much. I really appreciate it.

silk lark Oct 6, 2021, 9:22 PM

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both terms work

twilit mango Oct 6, 2021, 9:23 PM

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Excellent

silk lark Oct 6, 2021, 9:23 PM

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if you are interested in nitty-gritty details, Sparkfun has an article on it: https://learn.sparkfun.com/tutorials/logic-levels/all

twilit mango Oct 6, 2021, 9:24 PM

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Ooh. Adding to my list.

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Scanning that, it covers some other things I don't understand as well. Good find.

limpid nest Oct 6, 2021, 10:09 PM

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Could 3 strings of LED Christmas lights and 3 motors (can't access so can't give info about them) really only be pulling .5 A?

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Motors running with a load on them, also can't give a good estimate of the mechanical load at this time

worldly schooner Oct 6, 2021, 10:37 PM

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limpid nest Could 3 strings of LED Christmas lights and 3 motors (can't access so can't give...

Yes, if they’re running off of 110vac

limpid nest Oct 6, 2021, 10:38 PM

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They are!

worldly schooner Oct 6, 2021, 10:39 PM

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0.5A @ 110Vac is 55W, equivalent to 11A @ 5V or 9.2A @ 12V

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So that’s a fair chunk of power, despite pulling only half an amp of current…

limpid nest Oct 6, 2021, 10:41 PM

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Makes sense, it's been half a decade since I did any analysis in AC

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Thanks!

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I'm just getting current measurements for sizing relays, hoping to be able to spend less

rocky quest Oct 7, 2021, 2:31 AM

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SAMD21 Dev Board with JLCPCB's Purple

distant raven Oct 7, 2021, 2:38 AM

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Nicely done ✅

long wraith Oct 7, 2021, 12:44 PM

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That's such a pretty color

tough matrix Oct 7, 2021, 5:06 PM

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@rocky questnice indeed
but where are you getting your SAMD21s? do you have a secret stash or did you find a hidden treasure trove from old days?

limpid nest Oct 7, 2021, 5:24 PM

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major diameter of of 10 screw is 0.19", can I get by with a 0.2" mounting hole in my PCB?

unique patio Oct 7, 2021, 5:37 PM

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https://pages.mtu.edu/~suits/misc/tapsizes.html. Close fit for #10 is 0.196. However, I don't have any particular experience with PCB hole specifications and their tolerances.

limpid nest Oct 7, 2021, 5:41 PM

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Hm, maybe 205 mil or 210?

unique patio Oct 7, 2021, 5:42 PM

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is it plated through?

limpid nest Oct 7, 2021, 5:44 PM

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It's just a via so it should be

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that's how I've always done plated holes on PCBs

unique patio Oct 7, 2021, 5:47 PM

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These are recommended for M screws, but you could follow similar guidelines: https://pcbartists.com/uncategorized/pcb-drill-size-for-standard-screws-fasteners/

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no numbers but interesting: https://macrofab.com/blog/attaching-your-project-to-things-mounting-holes-and-what-to-watch-out-for/

limpid nest Oct 7, 2021, 5:49 PM

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I don't need to use 10 screws, they're just cheap and can be bought in a store, thanks for the guidelines!

unique patio Oct 7, 2021, 5:50 PM

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we use 0.1" holes and recommended M2.5 screws for those (howzat for mixing units?!)

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#10 is pretty big for a mounting screw

limpid nest Oct 7, 2021, 5:51 PM

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it is

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when designing stuff I don't always consider everything I should, and sometimes end up with a bad initial decision trickling thru, fortunately it's an easy fix

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I am probably going to use at least #4s, which are greater than 0.1", since my enclosure holes use that

limpid nest Oct 7, 2021, 8:57 PM

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I have some power cables coming into my enclosures, mostly 12V and 5V wall warts. What is the best way to make connections to a board that has pin headers? Should I solder to the pin headers or even leave the headers off and solder to the pin holes?

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Or use female dupont connectors?

worldly schooner Oct 7, 2021, 9:18 PM

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There are rectangular housings similar to that of a row (or 2) of female dupont connectors. Those would be my recommendation, as they're less likely to expose metal to potential short-circuit hazards and for the wires to move in undesirable ways.

limpid nest Oct 7, 2021, 9:18 PM

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what would be a term to google?

worldly schooner Oct 7, 2021, 9:19 PM

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https://www.adafruit.com/?q=wire housing pack for jumper cables&

Adafruit Industries, Unique & fun DIY electronics and kits

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Or you can look for 0.1" pitch rectangular housings

limpid nest Oct 7, 2021, 9:19 PM

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Oh that's what I meant by female dupont connector

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That's secure enough?

worldly schooner Oct 7, 2021, 9:21 PM

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Does your enclosure have moving parts?

limpid nest Oct 7, 2021, 9:21 PM

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Nope

worldly schooner Oct 7, 2021, 9:21 PM

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Should be fine

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The more pins, the more secure.

limpid nest Oct 7, 2021, 9:21 PM

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I'm connecting to a row of 8

worldly schooner Oct 7, 2021, 9:21 PM

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There are also connector options, if you google 0.1" or 2.54mm board-to-wire

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You could pick something with a latch lock, if that's a bit more comfortable for you

limpid nest Oct 7, 2021, 9:23 PM

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which of these would you click on?

worldly schooner Oct 7, 2021, 9:24 PM

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Housings for the cable end, or Board In, Direct Wire to Board for the through-hole connector for the PCB

limpid nest Oct 7, 2021, 9:25 PM

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OK, the only 0.1" pitch thing they had in Board in, Direct Wire to Board was a DIP ribbon cable assembly

worldly schooner Oct 7, 2021, 9:25 PM

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Eh?

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h/o

limpid nest Oct 7, 2021, 9:26 PM

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h/o? Here's my filter https://www.digikey.com/en/products/filter/rectangular-connectors-board-in-direct-wire-to-board/317?s=N4IgjCBcpg7ArATiqAxlAZgQwDYGcBTAGhAHsoBtERWAJgDYQBdEgBwBcoQBldgJwCWAOwDmIAL4kAtLRQh0kfgFdiZSiHjNxkkLMhUARqSx8AJgAJ2pcwHcBfAudSkhQgqit8tQA

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worldly schooner Oct 7, 2021, 9:26 PM

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https://www.digikey.com/en/products/detail/molex/0705430042/313745?s=N4IgTCBcDaIOwAYCsAWAzAhKIF0C%2BQA

0705430042 Molex | Connectors, Interconnects | DigiKey

Order today, ships today. 0705430042 – Connector Header Through Hole 8 position 0.100" (2.54mm) from Molex. Pricing and Availability on millions of electronic components from Digi-Key Electronics.