help-with-hw-design

[elder peak]

Being forced to make an adapter can really put a crimp on your style.

But, yeah, I get DEEPLY ANNOYED when they aren't sufficently specific with connectors.

[cosmic condor]

I'm trying to make something similar to a pcb ruler, but with a twist. It's for a project where I'm trying to make it easier for people to draw mayan glyphs, using an old and cool system called the "leroy lettering" (which is just a pantograph).
https://www.youtube.com/watch?v=5t1YLxb2hbY

(Fran Lab has a longer, nicer video if you want to geek out with old tools)

[cosmic condor]

How would one draw a relief ilke that on kicad, a can a manufacturer like oshpark make something like that?

[royal cypress]

Haha it's not! I started paying attention, and if this insanity isn't a good indication that it's adhered to, I don't know what is.

[tough matrix]

@cosmic condor I haven't seen pcb manufacturers that can do reliefs - typically the only milling they do is for the full thickness of the material

[cosmic condor]

@tough matrix Thanks for the input.

[median stirrup]

This PCB-potentiometer (assuming that's what it is) is wild! but what does the board do? https://www.bunniestudios.com/blog/?p=6062

https://bunniefoo.com/ntw/ntw_feb_2021_sm.jpg

[silk lark]

pretty colors

[median stirrup]

the internet tells me that due to the low resistance of copper, a PCB potentiometer would be useless

[silk lark]

it might be a variable inductor?

[median stirrup]

my assumption was those two fat green traces were feeding into either end of it and the wiper was tapping the semicircular trace in the middle

I suppose you could also build a PCB capacitor depending what's on the other side of the PCB, or in an inner layer

[silk lark]

variable capacitors usually have two (or more) plates that move in relation to each other

[median stirrup]

yeah that makes less sense than I thought

a half turn doesn't seem like much of an inductor either

[silk lark]

but note that there is no connection from the "wiper" to anything

[median stirrup]

I was imagining that rivet went through a trace on the bottom side, and then the trace coming out from under the nut near L3 was connected to it as well. but I can't say for sure it is

[silk lark]

but there is no wire going along the transparent part of acrylic

or is the wiper made of pcb and not transparent?

[median stirrup]

it looks like PCB with green silk to me

[silk lark]

oh, right, it's pcb

another possibility is that that copper trace is actually covered with some material with more resistance

usually carbon is used, but that would be black

oh, I know!

the actual thing being switched in on the other side, the wiper is only for connection to the center

a multimeter with a rotary switch

there is probably a second wiper on the other side

[median stirrup]

these I'm familiar with

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fsoftsolder.files.wordpress.com%2F2012%2F09%2Fimg_2331-multimeter-range-selector-switch.jpg&f=1&nofb=1

but as this looks like it's unbroken I'm not sure how it could have the same kind of function

2n5901 is RF transistor

[silk lark]

the traces on the other side are broken, this one is just for connecting the center

[median stirrup]

oh I see what you might be saying now

[silk lark]

they used a wiper for a better and more reliable connection, I guess?

[median stirrup]

thanks for chatting about this, I love this blog's monthly puzzles

gotta go now

[harsh pendant]

deos this SD card circuit seem right? Just wanna check before i get this board manufactured

[unreal flax]

Seems sane to me.

[spark sun]

designing some (more) PCB badges, anyone have any favorite part #'s for side-mounted SMD LEDs, preferably available from LCSC? I've been using the TOGIALED ones which seem OK but curious if there are any preferred.

sneak preview of the board art 😄

[distant raven]

Finally in Utah

Got my samples 😁

[carmine scarab]

Priority unpacking!

[distant raven]

Exactly!

[carmine scarab]

Welcome home I suppose!

[distant raven]

Office vibes

It even has a view of the mountains 😍

It’s dark now of course

[misty escarp]

looks great!

[ember laurel]

yeah that's a nice place

good luck finding those 0402 resistors once they hit the carpet though

[harsh pendant]

Deos this schem and brd look ok? any potenetial failed points?

[tough matrix]

looking at the brd image, it seems that in many places there is very little clearance between traces - for example, the trace going from resistor R9. But it may be artifact of low-resolution image. Did you run DRC?

[fervent lance]

ideally drc errors should not open

[tough matrix]

also: I don't see sda/scl pullups - are they included on bmp388 breakout?

[fervent lance]

they might be

looking at the footprint it looks like the adafruit one

[carmine scarab]

Yikes! Carpet though.. Zzzzzap!

[distant raven]

Yeahhhh

[carmine scarab]

5:48 and you're up? Someone's still on Eastern time!

[fathom lotus]

anyone else notice kicad 5.1.9 be a laggy mess compared to older versions? it feels like it's running like crap even though my system hasn't changed at all. running arch linux on pretty beefy hardware

looking in htop it's not even using many resources but it still feels really bad to use

[distant raven]

Very much on eastern time 😄

But only 6:51

[carmine scarab]

Meh, what's 3600 seconds between time zones!

[fathom lotus]

would appreciate if someone could check if this would work 🙂 rawvcc is 5v, 3.3v is obviously 3.3v, oled reset is 3.3v, b5 is 5v.
the oled (on oledreset) is reset when oledreset is pulled low by pin b5, but since the oled is 3.3v logic, the 5v from the controller would probably fry it. put in this bss138 level converter and want to make sure it's wired up correctly so that when b5 is high (5v out) oledreset is also high but with 3.3v out

also, should i put the same circuit (and also some pullup resistors) on the i2c lines?

[harsh pendant]

yes. ran drc no errors. scl/sda pullups included

[ember laurel]

phew, just got another order of my board out

JLCPCB with SMT assembly

I keep having troubles with their PnP

lots of manual coordinate and rotation tweaking required

264 components on the board, 58 unique

[haughty wolf]

what are your boards for?

[ember laurel]

dental motor control system

[haughty wolf]

of course lmao

[ember laurel]

JLC doesn't do edge plating though

I really wanted edge plating for this prototype :/

[dark fox]

I finished this a few weeks ago... but I wanted to post it because I literally knew nothing, zilch, nada about making a PCB and with some YouTube time, Fusion 360, OshPark and Seattle Makers (to do the assembly), I was able to make a PCB with some connectors on it for a work project.

Anyway.... point of that is just to say. If you put in the time... anyone can make a PCB project. Obviously my project was very simple, but still, if "I" can do it.. believe me YOU can do it !

[distant raven]

Beautifully done @dark fox

[misty escarp]

Looks great

[carmine scarab]

I love those copper(?) traces on the black. Very nice @dark fox !

[round fog]

@dark fox you're at Seattle Makers? That's rad, is Jeremy still running that place?

Nice job on your PCB

[dark fox]

Yes he is still there. I'm relatively new around the place.

[round fog]

It's a nice little shop. If you see Jeremy you can tell him Lucian says hi.

Are they still in that old hat factory building?

[dark fox]

OshPark afterdark looks pretty on most everything

[dark fox]

Hmm... I call it the School of Visual Concepts building \ art school building. Might have been a hat shop, but I don't know that history.

https://seattlemakers.org/

[round fog]

Yeah, looks like the same one. I basically lived there for about 6 months or so after the company I was in went belly up haha

I thought that Amazon was going to demolish that whole block and make them move but I guess they never got around to it

[dark fox]

.. yet 😉

[misty escarp]

The year is 2060, Seattle is all Amazon properties, drones occupy all apartments and the humans shelter in the remains of coffee shops in search of wifi or crackers.

[elder peak]

Okay, the 0805 415nm UV LED (https://www.digikey.com/en/products/detail/sunled/XZVS54S-9F/9920871) has an exceptionally odd package. No pads on the side, pads on the bottom. Still managed to get it soldered.

[tough matrix]

A really naive question:

why are we using load switches? what is the advantage over just using a mosfet?

[elder peak]

Wirehead's first rule of power-electronics: If you want to do something with power, somebody's probably packaged it as a load switch or a MOSFET controller.

The biggie is that if you want to make a high-side switch that's run off of a logic level, you are goinna need an n-channel MOSFET to drive the p-channel MOSFET to the right voltage, whereas a load switch can contain both bits.

The one that @distant raven has a breakout for will do an orderly charge/discharge with externally set values.

I've got a AP22815 soldered to a breakout to screw with it because it looks like it provides a really nice way to prevent power from flowing backwards over the USB line without the drawbacks from using a schotky diode.

[distant raven]

Tends to be pricier to build it with individual components too

Whereas a load switch costs like $0.30 for 10W

[elder peak]

I don't think @tough matrix asked a naive question, just... a loaded question.

Also, at least some of the time, the load switches come with more through anti-zap measures than the component parts.

[heavy jasper]

To expand a bit on “anti-zap measures,” load switches (nice ones, at least) tend to have things like built-in thermal protection, current limiting, and the like that reduces the likelihood of electrical overstress and device failure. In other cases, they will also more commonly use N-FETs which have better conduction/resistance properties but need a positive Vgs for high-side switching, so a load switch will package the switched-capacitor gate drive circuitry to enable that positive Vgs.

Some will even include internal scaled-down current mirroring FETs off the large FET, which means you can attach a resistor and read it as output current. These readings tend to have pretty wide error bars due to process variation and temperature, but are a lot cheaper and smaller (if you’re already buying the load switch) than adding an external shunt/amplifier circuit.

[tough matrix]

carefully writing it all down

@heavy jasper @elder peak thanks!

[fervent lance]

@elder peak Nice chip! AP22815 neat.

[frozen lichen]

Has anyone here had experience with making their own esp32 boards. i'm having some communication issues i could use a hand with troubleshooting?

[distant raven]

@frozen lichen what kind of ESP32?

[frozen lichen]

esp32-wroom-32u

[distant raven]

Using the mini module?

[frozen lichen]

on my uart its sending data to the esp32 but the esp32 isnt responding. yes using the mini module

[distant raven]

Can you swap the UART lines?

Or is it a PCB

[frozen lichen]

its on a pcb

hold on ill show you what my scope is saying

[distant raven]

Okay

[frozen lichen]

So Channel 1 is the TX snd Channel 2 is the RX

i've built up 2 boards and both are the exact same

[light ermine]

That doesn't look like a valid tx signal?

[distant raven]

I agree

[frozen lichen]

ill show you my healthy dev kit and what that shows

oh i dont have a photo of that :/

any ideas? im using a ft231x usb-serial interface. i can show you my schematic if you want?

That is my healthy dev kit and what that’s doing but like you say they look completely different

this is the schematic

[distant raven]

Ah yea your UART lines are not swapped

TX —> RX / RX —> TX

[frozen lichen]

ahh bugger okay, time to lift some pins 😅

[frozen lichen]

@distant raven its still the exact same :/ only reversed

[distant raven]

Are you getting 3.3V on the ESP32 power pin?

[frozen lichen]

ayyy sorry i dont know what i was doing wrong but im getting data through on putty now!

thanks 🙂 N

now im getting data out with putty but i can access it with esptool

got it

[distant raven]

Oh good!

🙂

[elder peak]

We were talking about the AP22815 and I did verify experimentally that it will block reverse voltages over the USB port and stuff

[distant raven]

That’s pretty cool

[unkempt remnant]

Quite a while back, I was trying to figure out what the reflow profile ought to be for an aluminum PCB, since the info that comes with the solder paste assumes you're working with FR-4. I contacted QuikChip, and their response was "you want to lengthen every phase in the reflow profile just enough for the board to hit the target temperature for that phase, and you don't have to do anything special to measure the board temperature (an infrared thermometer or temp probe is fine)"

Thought you guys might find that useful! It's definitely a better method than "reflow some resistors and squint at the pads to see if they look like they got correctly soldered".

@elder peak dangit, why is the AP22815 out of stock on digikey. I might have to resort to (gasp) mouser

[elder peak]

There's a buncha SOT23-5 parts from Diodes Inc that have the same pinout as the AP22815 but with slightly less current handling

[fervent lance]

I saw this the other day but I forgot what I learned about it. I think I said 'nice chip' after reading the datasheet (briefly). Load switching?

(let's have a breakout board on that ;)

Too many years of using relays for that. ;)

[elder peak]

It's a load switch with reverse voltage protection, plus over/under voltage and short circuit protection.

Also, cheap and small and handles 3A.

[fervent lance]

3A pretty nice!

[elder peak]

And it's got a FLG line that will blink if you managed to short circuit or overheat it or something like that.

So, as a breakout, kinda nice. As part of a Feather or something like that, even better.

[fervent lance]

I just use schottky's dumbly. Had a situation arise where the Raspberry Pi was ordinarily powering something, but that something had a secondary port for special occasions (uploading firmware by a second path using ST-LINK rather than the usual path).

I needed to prevent the secondary serial port from trying to power the Raspberry Pi (a hefty load).

[elder peak]

Nothing wrong with a Schottky.

Schottky is cheaper and arguably smaller.

[fervent lance]

I got some really good ones from DigiKey. Accidentally overspec'd. ;)

1N5822G I think

They worked so I considered it a done deal.

[ivory jasper]

Has anyone got a good power select schematic I can copy? I have two 5V inputs into this board with a built-in USB hub. I need to have it switch to the external 5V power when that gets plugged. I didn't think this would be this hard! haha

I had one that worked with three MOSFETs but it had a problem where if you plugged external 5V in then unplugged it the current from the other side (PC's USB VBUS line) would leak back through. Meaning I could detect the connection of external power once but then never again (because now that pin on my MCU would always show a 5V connection).

I don't mind using an MCU pin to detect external power and signal based off that but I thought something like this would've been solved by now

I expect to draw a max of 3A @5V (4.5V is OK but 4.4V is pushing it haha). Zero voltage drop is preferable though

[fervent lance]

@ivory jasper Every Adafruit target board has some form of two sources of power, detected and one is overridden by the other.

Metro M4 Express, Schematic:
https://learn.adafruit.com/assets/53093

[ivory jasper]

@fervent lance Excellent! Thanks

@fervent lance What's this disconnected resistor thing?

[fervent lance]

USB_HOSTEN connects to PB07 of ATSAMD51J19A.

[ivory jasper]

R1G$3 is just sitting there... Connected to nothing

[fervent lance]

So it's an output from the MCU.

[ivory jasper]

...but where? There's no label or anything

[fervent lance]

74125 is a level shifter.

I'm not answering your question at the moment.

;)

[ivory jasper]

Ahh

[fervent lance]

VIN seems sourced at cell A6.

So when 2.1mm DC supply is active, so is VIN.

I don't know what the unconnected resistor does or where it is.

They don't usually make mistakes .. the schematics are very good.

Pin 4 of 74LVC1G125 is an output.

https://assets.nexperia.com/documents/data-sheet/74LVC1G125.pdf

Pin 2 is the corresponding input, and Pin 1 is /OE ('not output enable - active LOW').

So you control it by Pin 2 which is tied to Pin 1.

Again this supports the idea that the MCU is controlling this level-shifter.

This is all in some effort to turn TR1 on or off. ;)

(This is more complicated than most of Adafruit's stuff)

(Just happened to accidentally pick the complex one!)

Here's Feather M4 Express, Schematic:
https://learn.adafruit.com/assets/57242

That one is more typical: VBAT vs VBUS.

They both feed a singleton AP2112-3.3 voltage regulator (3.3 VDC out).

Note the floating resistor tied to nothing on the upper left corner, too)

VBUS in this schematic is sourced only at the USB micro-B connector.

VBAT is a JST connection to a LiPo battery.

Obviously, in Cell A1 the aim is to have VBUS override VBAT to save on battery life, and (also) to charge the battery (Cell A6 of the schematic).

[ivory jasper]

@fervent lance Just tried to replicate this in Kicad... Does this look right?

[fervent lance]

VBUS forward-biases D4 (MBR120, a schottky diode?) whereas VBAT reverse-biases D4 (Thus D4 won't conduct and backfeed the USB port from the LiPo battery).

[ivory jasper]

So the point is just to disable TR1 when VIN is plugged in? What voltage does VIN need to be for this to work?

Assuming VIN is 5V that means the voltage divider is putting out 2.5V at TR1. I assume IC3 is boosting that somehow?

[fervent lance]

VIN is supplied by 2.1 mm DC barrel jack.

[ivory jasper]

In my schematic I've got VIN as a 5V-only external source. Meant to power the USB hub (and RGB LEDs)

(for reference, it's a keyboard with a built-in USB hub)

[fervent lance]

I'm leaning towards saying that when 2.1 mm DC barrel jack has (proper) voltage the VBUS of the USB connector no longer supplies power to anything we care about.

[ivory jasper]

Yeah that's the plan

[fervent lance]

I'm talking about the existing work Adafruit did. ;)

If you make any substitutions it's your job to see that 'they work'. ;)

[ivory jasper]

Well I don't plan any substitutions except maybe that MOSFET (if it's not in JLCPCB's part catalog)

[fervent lance]

USB_HOSTEN would be if you want to power a mouse or keyboard, I'd suppose.

In that instance you very much do wish to back-power the existing USB micro-B connector. ;)

[ivory jasper]

So USB_HOSTEN comes from the MCU... If it's HIGH it enables the external supply?

[fervent lance]

And ATSAMD51J19A decides if you get this privilege or not.

Or low. I didn't look.

(Haven't been thinking about it until 3 seconds ago)

[ivory jasper]

Right, it could be either... Doesn't matter though. The point is the MCU makes the decision as to which power supply gets selected

[fervent lance]

Yes, it needs to be able to power the USB port where it's appropriate to do so.

You could (of course) tie the MCU input to the level shifter, to one of the rails, for permanent duty.

[ivory jasper]

Oh so this just switches VIN -> USB VBUS?

[fervent lance]

(disconnecting it from the MCU before doing so)

[ivory jasper]

...so you can use USB OTG I assume?

[fervent lance]

answering questions in your parlance is 20x harder than explaining what Adafruit already did. ;)

[ivory jasper]

Sorry 😦

[fervent lance]

Nothing to be sorry about .. I always think this is symmetrical but it really isn't.

If I say yes and you get blue smoke ..

I think this is to provide for USB OTG or a mouse/keyboard or both. Don't know.

Probably just so you can use Metro M4 Express as a substitute for a PC's mouse or keyboard.

Note that VIN is only sensed locally - it does not supply anything in Cell A3.

It sits at the top of a voltage divider, only.

It's a sensing circuit.

NCP1117ST50TG3 sources DC +5 from VIN.

This is the same +5V at the leg of TR1.

[ivory jasper]

After looking at several Feather board schematics I think this one suits my application more

...except I'd replace VBUS with VIN and VBAT would be VBUS (from the PC)

That way VIN would get prioritized over VBUS

[fervent lance]

So I'd guess (only a guess) that TR1 prevents this source of +5 from back-feeding VBUS at the USB micro-B connector.

[ivory jasper]

That's from the Feather STM32F405

[fervent lance]

Yeah Adafruit did enough variants that if you comb through them you're likely to find a match to your application.

[ivory jasper]

Only problem I have with that STM32F405 schematic is D4 will need to be able to handle a lot of current. I suppose I could just make multiple connections off the VIN line

[fervent lance]

D4 bypasses the transistor there.

[ivory jasper]

You mean the MOSFET?

[fervent lance]

So the 'sense line' is VBUS on the GATE of the FET.

[ivory jasper]

Yay! I got it right then!

[fervent lance]

;)

I would not commit to permanent difficult to construct stuff until you've worked it out on the bench for sure. ;)

[ivory jasper]

My STM32F401 MCU has 5V tolerant pins (well, most of them are) so I can sense external power just by running it directly to a pin on the MCU (with a resistor of course--just to be safe)

[fervent lance]

;)

[ivory jasper]

Nah, I like to live dangerously!

[fervent lance]

I have CamelForth that'll run on that MCU. ;)

(any STM32F4x series seems to work)

[ivory jasper]

I'm designing revision 2 of the Riskeyboard 70 PCB. It's this thing: https://gfycat.com/alienatedflatcanvasback

[fervent lance]

Hehe. Nice.

[ivory jasper]

It'll have an entirely different USB hub chip this time around and a whole lot of pins have been remapped

Lots more dedicated connectors too

The previous version just had all the extra pins broken out at the back but this time I've got some that are meant for things like that display. So right now that display is plugged into several different GPIOs at the back of the keyboard that are kinda randomly placed. In rev 2 I'll have those all together in a set with their own 5V and GND too

Another lesson learned: Rev 2 is going to have WAY more mounting holes! haha

[fervent lance]

So what kind of display is that?

[ivory jasper]

Mounting holes don't hurt anything (except cutting up the ground plane I guess). So the more the merrier as far as I'm concerned. It'll give me more flexibility with the case design

[fervent lance]

I would be like a jazz player with dark sunglasses on, just to sit at that thing

[ivory jasper]

That is two 4-matrix MAX7219 displays soldered together in the middle

I have an 8-matrix one now though that I'll be replacing it with (same thing, just a solid PCB; so it's easier to keep straight)

[fervent lance]

No I mean what's the technology and geometry? Seems fairly dense in pixel-equivalents.

[ivory jasper]

8, 8x8 red LED matrices powered by 8 MAX7219 chips

Does that answer your question?

They make blue, green, and white versions too!

Though the white ones are like 3x the price! So forget that! haha

[fervent lance]

So it's 16 pixels high?

[ivory jasper]

8 pixels high

[fervent lance]

The video is deceptive - makes it look more fine resolution.

[ivory jasper]

Using this font: https://crates.io/crates/font8x8

[fervent lance]

I use a Lumex 96x8 RGB matrix with TTL Serial decoding (Hayes AT command set).

[ivory jasper]

This gif might help you understand the dimensions better as this was before I got the scrolling text code working 😄 https://gfycat.com/ethicalaggressivebrant

76543210: Each number is on its own matrix/display

Rev 2 of the PCB is also going to have a spot where the end user can solder a TSOP38238 to the board if they want infrared control: https://gfycat.com/marriedtediousaquaticleech

I also added a bunch of little solderable/cuttable solder jumpers so end users can re-configure how the LEDs work. For example, you can disconnect them and re-route them to an external connector. Or have the external connector start at the beginning or end of the LED chain.

I also still need to figure out a whole bunch of stuff like, "Where's the best place to put the buzzer?" hehe

[fervent lance]

Thanks so that's 7x7 glyphs on an 8x8 matrix.

[ivory jasper]

Technically it's an 8x8 font but normal characters only take up 7

It's the unicode stuff that uses the lower part (I think)

Because of how Rust does static compilation it'll only include the characters that you've got inside any &str in your code. So that means I can support loads of unicode characters without having to worry about how much space that'll take up on the MCU's flash 👍

[fervent lance]

96x8 works out to 32x3 or 16x6 or 8x12 columns.

[ivory jasper]

Well it's 8 displays so it's 64x8 🙂

[fervent lance]

So basically 12 columns with a square aspect ratio.

[ivory jasper]

I can tack on many more displays if I want. I could make it 64x64! A massive display hanging off the back of the keeb!

[fervent lance]

64 columns of LEDs is 64x1 or 32x2 or 16x4 or 8x8 - 8 columns square aspect ratio.

[ivory jasper]

Though my code right now only assumes it's one character row. That's easy enough to fix though 👍

This is the displays: https://smile.amazon.com/gp/product/B07X95H9DT

[fervent lance]

I'm presently thinking about adapting 80 columns of text to SRAM geometry.

(which wants say, 64 bytes per row rather than 80 bytes).

[ivory jasper]

Interesting

I just buy bigger chips! 😄

[fervent lance]

I want it to be efficient packing but I want the 80 column human factor.

[ivory jasper]

Oh I get it!

[fervent lance]

No it's endemic powers of two.

[ivory jasper]

Read the vt100 manual! That's exactly how it works!

[fervent lance]

16 bytes is the typical width of a DUMP.

I want it so that a hex dump corresponds more closely.

[ivory jasper]

Linux terminals "emulate" vt100 but a vt100 terminal was a physical thing and it had a very detailed manual talking about how you're supposed to store the characters in memory and whatnot.

[fervent lance]

Thinking about a 3-cycle: 32, 64, 96 like that but stop at 80.

[ivory jasper]

I believe they were 7-byte characters though

[fervent lance]

This is about RAM.

Storage locations.

[ivory jasper]

Why get so low-level? There's got to be an existing abstraction/lib you can use

[fervent lance]

If you were to create a text editor from scratch, using powers of two as the geometry, where do you pick your column width for human factors? How did they get to 80 columns, not 64 columns?

Forth is entirely low level.

[ivory jasper]

Aha! I know the answer to this one!

[fervent lance]

That's the point of it.

[ivory jasper]

Typewriters

Standard letter with standard typewriter characters gave you 80 columns to work with

[fervent lance]

Right but on a computer, you have SRAM geometry to consider - wasting valuable SRAM by ignoring the 'extra columns' that don't fit into a power-of-two schema.

[ivory jasper]

That's how I learned to type! Using IBM typewriters (not the ball kind either--the old school lever-the-damned-character-on-to-the-page type)

[fervent lance]

64 columns would be inhibiting; 96 is too wide. ;)

[ivory jasper]

Well, in the vt100 manual I believe the extra bits were used for storing metadata about the characters

[fervent lance]

I think we're now well outside the scope of #help-with-hw-design (sorry to the channel).

[ivory jasper]

ABC<special bit indicating bold text>DEF<bit indicating the end of special font> etc etc

Yeah probably

[fervent lance]

#general-chat or #general-tech better for current thread. ;)

[ivory jasper]

So I'm redesigning this PCB and I have boatloads of room... Anything cool I could do with all that space? 😄

I've got the IR receiver, a buzzer, LED reconfigurability, an LED output port (multiple, actually), and a few other nice things but I'm like the Little Mermaid here. I want mooooooooore!

[fervent lance]

I would put in a monitor MCU.

[ivory jasper]

Well, an extra MCU is a ton of work. I'm talking about... "add place where the end user can use some of those external GPIOs for <insert cool/useful IC>"

[fervent lance]

You can get one of them castellated pads breakouts and just solder it flat.

[ivory jasper]

Oh, you mean add a spot to solder in an external MCU board. Interesting

[fervent lance]

Yeah would be an add-on you don't have to populate if you don't need it.

[ivory jasper]

What would you use such a thing for on your keyboard PCB?

[fervent lance]

Run lots of traces to/from it to all your cool stuff elsewhere on the board.

I would do it and then find the uses.

[ivory jasper]

Hahaha! Sounds like something I'd do hahahaha

[fervent lance]

Like an analog synthesiser that has hidden MIDI inside to control all the front panel stuff or at least 'read the patch'.

[ivory jasper]

I'll add a place for that new ESP32 board that replaces the ESP8266. That way the end user could get their keyboard on wifi!

Log data via MQTT

[fervent lance]

Yeah an SD card reader slot.

[ivory jasper]

Rather, invoke macros on the keyboard that do IoT stuff

[fervent lance]

You can have a lot of terminations that you don't populate.

That way it's more universal; when you think of an application that needs an SD card you're not hanging stuff outside the cabinet to do it.

[ivory jasper]

Yeah that's why I was asking for ideas. Now you have me thinking I should use a 7-port USB hub IC instead of the 4-port one. It'll still only have 3 external USB ports on the keeb but there would be 4 you could connect to via headers (or similar)

That would only work with USB 2.0 though. Stuff like that is impossible with USB 3+, sadly (due to the ridiculously complicated and intolerant spec)

Just had a cool idea: An edge connector that exposes the D+/D- pins, provides 3.3V/GND and 5V/GND, and SPI bus pins. That way you could communicate with a USB device (that the PC sees) via SPI. Just slap it on there! hehe

Hmmm... Might be worthwhile to make a display that can be controlled like that

I2C might be more practical than SPI though

[fervent lance]

the ISP connection went away for a while now I'm in backlog

[jolly sphinx]

Folks, this is day zero of using KiCAD. I’d like to build a board where an Adafruit Feather plugs in. Should I start with this feather wing template and then start adding things? (https://github.com/ppelleti/FeatherWing-template-KiCad) Or is there a way to build my schematic and call the feather a component and insert it into the schematic and layout? I can’t seem to figure out how to import a feather as a component. Any suggestions or pointing me to resources or examples is welcome.

[pale current]

Coincidentally I started trying to do something similar a couple days ago. I used the template just to see what they did, but then added the components on my own (really just the headers)

[ivory jasper]

@fervent lance For reference, this is the schematic I ultimately went with.

It seems to work fine in a circuit simulator: https://tinyurl.com/yc8gxf7q

Oops, here's the correct URL: https://tinyurl.com/yc6r6dmu

Oops again: Looks like I need a version of this mosfet in reverse with the drain on the other side

[fervent lance]

@ivory jasper I have literally wired up one MOSFET in the last 15 years. ;) I use BJT's mostly.

But I bought some good ones recently for this very type of application.

[ivory jasper]

I'm getting this assembled PCBA 👍

[fervent lance]

I still can't read a schematic with a MOSFET in it but I can intuit what 'must be' going on in some cases.

What's that going to cost?

I think I'm getting jealous ;)

[ivory jasper]

$0.10

[fervent lance]

What's PCBA

[ivory jasper]

PCB Assembly

It's FREE at JLCPCB. Though they charge you a few bucks extra for things that aren't a "Basic Part"

[fervent lance]

Howzit cost ten cents. . what is this verb 'getting' mean that you've just overloaded. ;)

[ivory jasper]

The MOSFET costs $0.10

[fervent lance]

Okay so no ten cents.

[ivory jasper]

PCBA just costs you the parts plus like a $4 "engineering fee"

[fervent lance]

That's not the cost.

[ivory jasper]

I got five keyboard PCBs with two of them assembled for $150 last time I ordered

[fervent lance]

How much money do they ask before they will let you have this thing.

Okay 150 now we're talking.

[ivory jasper]

Nothing. Just try it

Well a keyboard PCB is huge

[fervent lance]

If you keep saying 150 is zero I'm hanging up this telephone. ;)

[ivory jasper]

I got 5 numpad PCBs assembled (with 23 hall effect sensors) for just over $50

That included the cost of making the PCB + the cost of all the components + the cost of assembly services

[fervent lance]

I would think about ordering with other people.

I don't see why that culture hasn't blossomed here.

The poker chip people used to go in on group buys and that was boocoo bux.

But you'd end up with a nice set of ASM custom clay chips.

[ivory jasper]

@fervent lance Here's the full cost breakdown!

[fervent lance]

That's really not bad.

I've flushed more than that and had little to show for it. ;)

They must have quite an operation to price it that low.

[ivory jasper]

@fervent lance Here's the cost breakdown of my 70-key analog hall effect keyboard with integrated STM32F401CCU6, LDOs, hall effect sensors, WS2812B-B RGB LEDs, and some other stuff

Those build times are BS BTW... It took them like a week and a half haha

Well, the PCB was actually 3 days. That's correct

PCBA took much longer than a day haha

[tough matrix]

pretty reasonable

[fervent lance]

Is this happening in the same country you live in, or do you wait 3 weeks for it to cross an ocean to arrive at your door?

[ivory jasper]

Yeah, especially for the sheer size of the PCB. OSHPark wanted like $2000+ just for the PCBs!

[fervent lance]

I think I've seen your photos before.

[tough matrix]

@fervent lance looking at the quote, I am sure it is JLCPCB - so China

[ivory jasper]

@fervent lance It was about 2.5 weeks from when I ordered to when it was delivered. I paid extra for FedEx shipping though. If you don't mind waiting they have super cheap shipping options

[tough matrix]

but DHL from them to US takes less than a week

[fervent lance]

That's very cool.

[ivory jasper]

It was at Christmas time too!

[fervent lance]

So you have to understand some kind of printed circuit board design/language I'd guess.

[ivory jasper]

I mean, I ordered on December 13th!

[distant raven]

2 layer boards?

[tough matrix]

I am waiting for my own PCBA order from them... 300 small boards

[ivory jasper]

@distant raven Yeah but 4-layer boards are only like $4 more haha

They do 6-layer boards for $8 more! Which is crazy!

[distant raven]

You should try messaging Drew

[ivory jasper]

They will only assemble one side of your PCB though. No matter how much you're willing to pay 😦

Who's Drew?

[distant raven]

He’s one of the OshPark peeps

[fervent lance]

that's off the hook. Must be a lot of fun doing all that.

[distant raven]

If you’re willing to purchase a lot of sq inches, they can work with you on price

[ivory jasper]

@fervent lance I just made the whole thing in Kicad. There's a plugin you need to install that exports the BOM in the proper format and their site sucks and doesn't preview properly but none of that matters because they'll just email you anyway and fix everything by hand for you so 👍

[distant raven]

Typically what you see if for the average maker

[tough matrix]

I am more annoyed that JLCPCB don't do V-cut panel for PCBA. Only stamp holes
Which is why I ordered it as 300 separate boards instead of 50 panels

[ivory jasper]

@tough matrix I know! I just tried to order v-cut with PCBA and got denied

[pearl tapir]

@tough matrix You could do mouse bites.

[ivory jasper]

Had to re-do my whole board with mouse bites and panelize it myself

[tough matrix]

they say so explicitly in their FAQs
can't imagine why

[fervent lance]

Yeah I have an extreme problem learning.

[ivory jasper]

@fervent lance Well at least you don't have to learn math for this haha

More a matter of getting the hang of the keyboard shortcuts so you can work efficiently

[fervent lance]

Somehow I get information in. Once it is in I can use it quite effectively.

[tough matrix]

@ivory jasper what's wrong with learnign a little math? 🙂

[ivory jasper]

I didn't know anything about Kicad 4 months ago!

[fervent lance]

5 times 3 is 15

[tough matrix]

usually

[fervent lance]

;)

Or 0x0F

[ivory jasper]

@tough matrix Because it requires going back to the beginning every time. If you don't do math very often your whole life you forget all the processes to solve any given problem. So to solve problem X you must first re-learn how to solve A-W

[tough matrix]

I was joking
I teach math for living

[fervent lance]

People who understand 'real' math do it the way I/we read schematics. It's a language.

[ivory jasper]

My long-term memory is 37th percentile 😦 So things like math lessons from high school are long gone

[tough matrix]

I don't remember which percentile my memory was

[distant raven]

Me neither. Probably bad lol

[ivory jasper]

Probably better than you think. Average people have fantastic memories compared to me

My short term memory is 97th percentile though! So apparently in the womb I traded one for the other haha

[distant raven]

Lol

[fervent lance]

Like I said earlier, interpreting what someone else has asked is worlds apart from explaining out a schematic following one's own reading of it, and in that exact sequence.

I have the ability to pick arbitrary places in a schematic diagram, and trace them and make good intuitions about why those traces are there.

[tough matrix]

@fervent lance I do "real" math, but... sometimes I talk to some colleagues and I see that difference between them and me is about same as between me and C-student of middle school

[distant raven]

It’s interesting that I can assemble something, disassemble it.. leave it for months and then be able to assemble it without instructions months later

[fervent lance]

;)

It'd be very exciting to be on a team working together, each with strengths and weaknesses, and no posturing about who can do what and who can't.

[tough matrix]

@distant raven - so you all settled in your new place?

[distant raven]

Well, we still need to go buy new furniture

We left a bunch with my sister who had none

But I make... pretty decent money and should have a good return if the IRS could get their act together

[tough matrix]

they will.. one of these days

[distant raven]

And then I’ll be making some part orders too, submit my order to form my LLC and get my business bank accounts setup

🥳

[tough matrix]

DO you need to register it as LLC?
In NY, you can just register the business name - if you are sole proprietor

[ivory jasper]

LLC is important from a legal protection standpoint

Get your LLC in Florida. It's slightly cheaper than Delaware and offers pretty much the same protections

(you can setup your LLC in any state--no matter where you live or where your business operates!)

You can do it online and have your EIN in ten minutes. It's kind of ridiculous

Half an hour later you can have a bank account and a debit/credit card!

...all operating under the business name

[tough matrix]

but what kind of protection LLC gives?

[ivory jasper]

...and if you have some major liability problem where someone sues you for millions you won't owe anything. The business itself will just declare bankruptcy and your own personal assets will remain yours

@tough matrix ^

...unless you're a scammer in which case a judge will seize your personal assets anyway. That's called "piercing the corporate barrier"

I've had an LLC and an S corp! I know all about it 😄 👍

"Why an S Corp?" An S corp is easier to "sell" to a great big C corp later

[tough matrix]

how much is Florida LLC?

[ivory jasper]

I think it's $125 last I checked?

This is who I used last time I did it: http://affordablecorp.com/

[tough matrix]

That may be worth it, indeed
Maybe once my revenue crosses $1000 mark, I'll do it

[ivory jasper]

(no affiliation)

[distant raven]

$75 filing fee for Utah

[ivory jasper]

Looks like it's $160 now

[distant raven]

I’m going through LegalZoom just because I don’t necessarily have a lot of time to research all the licensing and tax forms for the state so they will compile them for me to complete

And do all the other stuff I just don’t have a lot of time to do otherwise

[ivory jasper]

Every year you need to file an annual report and pay $200. Don't forget or it'll cost you like double that later in the year! haha

Nooo! LegalZoom is waaaaay overpriced. You don't need any of that!

[distant raven]

Yeah, I had a corporation before

I’ve owned many businesses

I know legalzoom is generally overpriced but it’s okay, I’m not really bothered

[tough matrix]

$200/yr is a lot
At the moment my Tindie shop certainly doesn't bring $200 profit/yr, so...

[distant raven]

Most businesses are luck to turn a profit in their first year

Assuming they survive the first 5 years, usually by year 7 they can turn a tidy profit

Unless your doing SaaS software and then you just perpetually operate at a loss and just raise VC money to cover your losses for growing too fast

[pearl tapir]

You might also look into forming you Company in Nevada. They seem to keep things a lot more private if it matters.

[ivory jasper]

Can someone explain to me the MOSFET on the left? It looks like a P-channel MOSFET but is it enhancement type or depletion type? It looks like it's supposed to be the depletion type but the symbol has dashed lines on the left which I thought indicated the enhancement type? I can't find the data sheet for that DMG3405 anywhere.

[fervent lance]

https://cdn-shop.adafruit.com/datasheets/1794datasheet.pdf

P-Channel enhancement mode power MOSFET

I don't know anything about them (much) 'but I test well' (I do well on guessing in standardized tests).

My guess is Adafruit only sells bread and butter items, and this is their only offering in this category, besides the N-Channel unit.

[ivory jasper]

@fervent lance That's not the data sheet for the DMG3405

I need to figure out if AO3401A will be a suitable replacement for the DMG3405 in that schematic

[fervent lance]

It's a load switcher. Pretty much any power MOSFET of the right polarty should be fine.

Check other Adafruit schematics that have similar circuits. You might find a live part number.

[ivory jasper]

I'm hoping this is right

I've simulated it here and it seems to work as expected: https://tinyurl.com/yb73gn6z

[fervent lance]

https://www.diodes.com/part/view/DMG3413L?BackID=8360

Just get the polarity right on the mosfet.

Should be enhancement mode but I don't know that that is.

My guess is that fourth digit of the MOSFET part number in the DMG series relates to P or N channel.

So that '5' should correspond to polarity.

[ivory jasper]

"for an p-channel enhancement mode MOSFET: +VGS turns the transistor “OFF”, while -VGS turns the transistor “ON”."

[fervent lance]

I just don't know. ;) I'm planning on using the adafruit big power mosfets to do simple stuff.

The little arrow points out from the Gate in the schematic.

The opposite type has that little arrow pointing in.

If you check several Adafruit schematics and they all have the arrow pointing the same way from the Gate, you can be pretty sure it's the correct symbol for that part.

[ivory jasper]

Well I was confused but I think I just figured it out: The 100k resistor to ground is what turns the P-channel enhancement mode MOSFET "on" when there's nothing connected to the other supply. That's the part I was missing in my head because when the gate is 0V it's normally OFF

[fervent lance]

RP2040 board has DMG341 for Q3 and is of very recent manufacture.

[ivory jasper]

...so the AO3401A should work in my case. Since it's just handling the PC's USB VBUS line (and not VIN from the barrel jack) it should be able to handle the current

I mean, it can handle -4A @-10V

[fervent lance]

The 340 embedded in your part number says it's probably the same part, and the odd fourth digit (it's 1, not 2 or 4 or 6) says it's the right polarity (I think).

If you get it entirely wrong it'll be obvious when you power it on. ;)

[elder peak]

So, the MOSFET in that particular situation has a pull-down resistor

You pretty much always want a 10k-100k pull-up or pull-down resistor to ensure that the MOSFET starts at the correct state.

[ivory jasper]

Well that's part of the reason why I'm willing to "just order the PCB" with this: Worst case is that I wire both 5V sources together and the load will just get shared between them. It's just to provide supplemental power so the LEDs can reach their maximum blind-you brightness (and provide power to USB devices plugged into the hub) 👍

Everything will still work without external power. It's just nice to have

Powered LEDs, powered USB hub, etc

[elder peak]

Also, a DMG2302UK is a pretty reasonable equivalent to the N-ch SOT-23 MOSFETs that adafruit uses, the DMP2045U is a pretty reasonable P-ch version, the DMC2020USD is a MOSFET array for the N/P combination that I have used on a board..

Oh, crap, right, those might not be available via JLCPCB's PCBA

So, check this out: https://lcsc.com/product-detail/PMIC-Power-Distribution-Switches_Diodes-Incorporated-AP2171WG-7_C110466.html

[ivory jasper]

Yeah for something like that on JLCPCB you have to start with "MOSFET" in the search and then whittle it down by clicking the "Basic Parts" link/button hehe

Just because it's at LCSC doesn't mean it's at JLCPCB

[ivory jasper]

Yeah there's a whole bunch of ICs like that but they all have one problem in common: They limit the current too much!

[elder peak]

How many amps are you drawing? Here's a 2A that they've got in their catalog: https://datasheet.lcsc.com/szlcsc/1806081742_Diodes-Incorporated-AP2111SG-13_C151559.pdf

[ivory jasper]

USB 3.0 spec says that each port can get 900mA. So say you have just a 4-port hub. That's 3.6A of power!

At full brightness with all LEDs white and the display connected I'm drawing about 3A @5V

[elder peak]

Ah, yah, the beefyboi load switch I've been messing with isn't on there.

[ivory jasper]

...but the USB hub is powered so I need to factor that in too. There's three USB 2.0 ports so I want to provide a least 500mA power to each. So that's an additional 1.5A. Total: 4.5A

Just realized the Shottky barrier diode I chose only does 3A. I might need to upgrade that

Yeah I'm going to swap the SS34 with an SS54

So if the external supply is 5V the drop from the diode should bring it down to ~4.6V. Wondering if I should bother boosting that up to 5V somehow for the USB ports. Hmm

Haha: https://electronics.stackexchange.com/questions/509032/boosting-3-0-4-6-volts-to-5v (schematic look familiar?)

Only problem: No answers!

[distant raven]

Interesting thing about that transistor in the Adafruit circuit

So it is used as a switch but for specific reasons

[ivory jasper]

@distant raven You mean the MOSFET? There's no transistor

[distant raven]

When it’s “on” (no USB power) it essentially acts as a small value resistor. But when usb power is applied it actually acts as a diode

MOSFETS are transistors...

FET = field effect transistor

MOS = metal oxide semiconductor

[ivory jasper]

Right

[distant raven]

I know what I’m talking about, trust me. I have a fancy degree in computer engineering

Lol

[ivory jasper]

It just confuses me because a regular transistor has its own symbol whereas MOSFETs are entirely different

[misty escarp]

I got my degree in Applied Acronyms and Initialisms so I know too

[distant raven]

It’s because there are different types of transistors

[elder peak]

The M isn't really for metal, it's for "Maaaaagic"

[distant raven]

BJTs are bipolar junction transistors

[elder peak]

MOSFETs work by fairies dancing on the die.

[distant raven]

CMOS complementary metal oxide semiconductor transistors (common for a lot of basic electronics components)

[distant raven]

Shhhhh you’re not supposed to reveal secrets like this

[elder peak]

But, seriously, all of the bits on the MOSFET symbol are there to remind you of the various bits and aspects schematically. Like the bulk and the body diode.

[distant raven]

Yeah

[elder peak]

Or extra terminals.

That being said, as a non-EE, I still have to look at what the heck each of the terminals are and make sure I'm not mixing up my N's and P's.

[distant raven]

The body diode in the case of the Adafruit enable switch ends up being pretty important for blocking voltage to the battery

@heavy jasper has a pretty detailed explanation of this

More nuanced

[ivory jasper]

I just found this: https://datasheet.lcsc.com/szlcsc/Texas-Instruments-TI-TPS61040DBVR_C7722.pdf

It's a DC/DC boost converter but I noticed something interesting: It has an EN pin so it can act as a switch!

Here's why that's cool: Each WS2812B-B RGB LED uses 1mA each when off. If I use this little $0.25 IC to boost the 4.6V to 5V I can also power them all completely off using a pin on the MCU 👍

I'll have to use more than one of them since it can only handle 400mA each

My only concern now is, "How noisy are they? Are they going to mess with my analog signals?"

[ivory jasper]

Looking at various schematics of powered USB hubs it looks like there's two ways it's usually done:

1. You literally just connect the VBUS lines to the external 5V supply (no ICs, nothin!)
2. You use something like a 9-12V external supply and use LDOs to provide 5V.

The problem with #1 is that it doesn't prevent reverse current going all the way to the PC

[distant raven]

Load switch

Load switches more often than not have reverse voltage and current protection

Depending on your power needs, you can get 10-20W of load switching pretty cheaply

[ivory jasper]

Got an example?

[carmine scarab]

Sort of like Diodes and LED, which are Light Emitting Diodes. Though the symbol for LED is a bit closer to a "plain" diode

[flat vigil]

what would cause a clock signal like this?

the high value is 3.3v and the 1/3 value is 1.2v

debugging https://twitter.com/tannewt/status/1369458529501782021

Scott Shawcroft (@tannewt)

Feather rp2040 sacrificed for @CircuitPython flash testing and debugging.

Twitter · Mar 10, 2021, 1:22 AM

[heavy jasper]

Some receiver pin supposed to be an input but actually an output with some lower frequency output would be my first guess.

(And depending on what value that output is, cutting off the top or bottom half of the clock signal by contesting drives)

[tough matrix]

@ivory jasper or - if you are willing to work with 9-BGA - you can get this boost converter, which gives you up to 3A@5V with enable:
https://www.digikey.com/en/products/detail/texas-instruments/TPS61253AYFFR/7653234

or this one for somewhat more manageable package: https://www.digikey.com/en/products/detail/microchip-technology/MIC2875-5-0YMT-T5/5283858

[ivory jasper]

@tough matrix Neither of those parts are available at JLCPCB 😦

At this point I'm thinking of living dangerously with the 2.1mm barrel jack going right to the VBUS lines on the USB ports

[flat vigil]

Looks like it was a bridge between SCK and MOSI

[heavy jasper]

That would do it!

[distant raven]

Tps22917 is good for 5V/2A

[ivory jasper]

Also not available at JLCPCB

[distant raven]

TPS2557 is an adjustable up to 5A

5V/5A

https://www.oakdev.tech/store/p8/TPS2557-Acorn.html#/

https://www.oakdev.tech/store/p1/TPS22917-Breakout.html#/

[ivory jasper]

Also not available at JLCPCB

[distant raven]

They are pretty easy to solder on, especially the tps22917

It’s sot223 6 pin

Doesn’t look like JLCPCB carries any load switches

[ivory jasper]

I just found the TPS22965

That might work

[distant raven]

Not bad

How much current are you using?

Or anticipating

[ivory jasper]

I'm only using max 3A but in theory it could require 4.5A

...but I have no problem using two 🤷‍♂️

...but that TPS22965 can do 6A which is more than enough

[distant raven]

Yeah

And I don’t think USB carries over 5A

[ivory jasper]

Well each port can do up to 900mA according to the spec

(USB 3)

...and the keyboard has 3 ports exposed to the user

Actually the theoretical max here is 5.7A

...which is still within the 6A of that load switch

[distant raven]

Yeah, should be fine

[ivory jasper]

Looks like it enables the switch if the ON pin is high. So I can just route VIN to the ON pin or trigger the ON pin from the MCU

Basically using it like a diode haha

Wish it was the opposite: High turns it off

[distant raven]

You want a low side load switch

So something that’s N-Channel switch rather than p-channel

[silk lark]

continuing the flattening

[misty escarp]

looks great!

Also thanks again for that state machine trick, it worked a charm

[silk lark]

great!

[woven ibex]

Not necessarily PCB design, but I did find an awesome circuit board font I wanted to share. It's called Circuit Mage, found on dafont.com. I combined my name and a circuit board vector and lasered it onto a piece of leather! Nerdy belt in process!

[silk lark]

very cyberpunk!

[elder peak]

yah that's amazing

[distant raven]

That’s pretty cool

[ocean anvil]

Hello! New to the server, so I am hoping I am doing this right... What do ppl think about a feather that has an I2C multiplexer and Stemma Qt connectors? Is there something like this out there?

basically a blend between https://www.adafruit.com/product/4515 and https://www.adafruit.com/product/4704

[misty escarp]

A feather or a feather wing?

[ocean anvil]

feather wing!

I have a few prototypes that use the ESP32 Huzzah feather

[misty escarp]

That sounds cool

[misty escarp]

What size screws do folks use to mount adafruit products? m2.5 should just fit a 0.1" hole, right?

Where do you source your 2.5s if you use them? I called and my local hardware stores don't carry those

[carmine scarab]

Pretty much any electronics or hobby store, digi-key, amazon. and yeah, m2.5 should but, but also want to be sure you get them long (or short) enough

[misty escarp]

Yeah I'm lasering some .22" plexigass so they can't be too short

[carmine scarab]

.22"? Definitely don't want to come up short!!!

Even more so if you're using 2!

[misty escarp]

Just the one heh

[carmine scarab]

😅 whew!

But also, lasers!!! 👁️

[misty escarp]

THere needs to be an eye protection sticker

[misty escarp]

Seems like a Cave Johnson kind of sign

[distant raven]

I need that

[elder peak]

@misty escarp check this out: https://amesweb.info/Screws/Metric-Clearance-Hole-Chart.aspx

[misty escarp]

Heh I had that open just now!

I always like to confirm what I find with others though

thanks!

[elder peak]

I got an assortment of M2.5 screws on Amazon and have been growing the sizes as I assemble more complicated things via McMaster Carr

[misty escarp]

I was thinking of using McMaster, but I need to justify the cost to myself first

[elder peak]

Adam Savage has a whole video exclaiming the glories of the McMaster Carr catalog on his Tested channel.

[misty escarp]

I looove McMaster

[elder peak]

Yah, I basically decided that any money I saved from getting it somewhere else wasn't really worth the effort.

Oh, and McMaster makes files meant specifically for plastic and it's just the thing for touching up laser cut parts.

[misty escarp]

Ooh nice

[elder peak]

So, yah, basically I have the DigiKey cart and the McMaster Carr cart and I add things to each of them to fit my anticipated needs until it's enough to economize on shipping and I want it bad.

They have taps meant for tapping holes in acrylic.

And drill bits for acrylic.

[misty escarp]

I've used those!

They are nice

[unkempt remnant]

Hmmmmmmm I am intrigued

Might have to check out the acrylic tools

[tough matrix]

Must be a very thick acrylic...
Can't imagine tapping threads in 1/8" - that is, I can imagine tapping threads, I can't imagine these threads actually holding anything

[elder peak]

I mean, sometimes you have to thread carefully.

[tough matrix]

I should laser-cut acrylic piece in the shape of Texas, with text "do not thread on me" 🙂

Or is it SC?

[misty escarp]

I've seen that flag in canada so I think it's anywhere.

Could be a good sticker for a tap set

[carmine scarab]

Texas is more the canon with one star over it and "Come and take it"

I think the "Don't tread on me" originally came from Metallica's song /s

In reality, I think it was from the colonists during the revolutionary war. With the coiled snake on a yellow field

[elder peak]

I prefer to say "no step on snek"

[distant raven]

Happybuy Reflow Oven T960W 110V Reflow Soldering Machine 4500W 300 x 960 mm Professional Infrared Heater Soldering Machine Automatic Reflow Machine (T960W 110V) https://www.amazon.com/dp/B07SW37SNP/ref=cm_sw_r_cp_api_glt_fabc_K454AP95NJF0XHTTHKZ9?_encoding=UTF8&psc=1

This would be sweet to have

I just need to sell checks math

200 LiPo power packs

Well, maybe 210 more

[frigid seal]

What are you using now?

I've got the generic Chinese TP-something-something Reflow oven.

But it burns boards and I've heard that that is because it uses direct IR instead of hot-air.

[elder peak]

HAPPYBUY is a great name

[distant raven]

I use a hot air reflow gun

Need to get something more hands off to boost my ability to produce boards more consistently

[tough matrix]

did you think of turning a toaster oven into a reflow? using a temperature controller - e.g from unexpected maker

[distant raven]

I’ve thought about it

[spice vessel]

Does anyone have any experience sniffing a SPI buss? I am trying to sniff an sd card reader using something like this: https://www.sparkfun.com/products/11468. I just want to know what data is being read/written from the sd card. Any help would be greatly appreciated

[silk lark]

what do you have so far?

[spice vessel]

@silk lark tbh not much. My general idea is to try to read all of the data that the master is reading. Ive been able to hook up the SPI lines to the reader but not sure how to sniffer them. I would rather not write a library from scratch

[silk lark]

I think you can use two spi buses, with shared clock, both in read mode, one for each of the data lines

[spice vessel]

wdym exactly?

[silk lark]

I don't understand

[spice vessel]

What do you mean exactly? Like would I still hook up MOSI and MISO normally and set both to read mode?

[silk lark]

you would hook up miso to one spi bus, and mosi to the other, both to miso on their respective buses

then clock and cs would be common

ah, but you would need an spi slave for that

I don't think circuitpython has that

[spice vessel]

@silk lark Could I put them both on the same bus? Why do they have to be seperate

[silk lark]

you only have one data input pin on a bus

but you need to be an spi peripheral, not master

[spice vessel]

Could it be bitbanged using other peripherals?

It sounds like this is going to get pretty complicated pretty quick

[silk lark]

you can, but then you need an interrupt support to handle reading the clock — and CircuitPython doesn't have that

[spice vessel]

Ill probably be making this in C++ so thats not to much of an issue

[silk lark]

if you need the data on your computer, you can just get it with a logic analyzer

well, in C++ you should be able to use the spi peripherals in the slave mode

[serene ermine]

I was hoping someone could have a quick skim over my pcb design, I think it's just about there but I'm really hung up on how to connect this usb-c Package. I've attached the relevant part of the schematic - labels VCC go to VCC on an Atmel 328P-PU & Pins 4 & 5 go to the same MCU.

[silk lark]

that fuse is between VCC and VCC?

also, not sure if connecting the shell to gnd is a good idea

[serene ermine]

Yes

Although I've possibly mislabelled this a bit

What i have called VCC is actually the output of VCC and AVCC on the Amel

[elder peak]

I have been using the RC filter between shell and ground in this Atmel datsheet: http://ww1.microchip.com/downloads/en/Appnotes/doc8388.pdf

[serene ermine]

Which i believe should produce +5V

[serene ermine]

The shell being the case of the usb-C connector? what would you propose I do with it? leave it hanging or as a NC?

I've also spotted an error in the zener diode placement, one should be on DN2 & the other DP1, I've fixed this now

[silk lark]

shell should be connected to the case

if you have no case, leave it unconnected

[serene ermine]

Will do

[tough matrix]

BTW: what is the purpose of the diodes between DP and GND?

[serene ermine]

I'm not sure, it was in the ref I used for connecting the usb c port

[silk lark]

overvoltage protection

for ESD and the like

[distant raven]

Nothing like ~15k components right in front of you

[fervent lance]

;)

[carmine scarab]

Less scary than ~15k$💲of components in front of you!

[elder peak]

That's when things get reel

[distant raven]

Reel expensive

Lol

In other sad PCB news, I managed to lose a $7/$8 ADC chip over the course of my move 😢

[tough matrix]

Adafruit posted a blog entry quickly showing how they design custom silkscreen in illustrator:
https://blog.adafruit.com/2021/03/15/custom-pcb-silkscreens-feather-rp2040-in-adobe-illustrator/

they didn't provide much detail of the process, though

anyone done something similar? not just importing one image into Eagle, but fully replacing the whole silkscreen layer with a custom design?

[distant raven]

I’ve not tried

Only done the bitmap import which is kind of a pain to learn

[misty escarp]

I've imported .dxfs

there's also hte SVG to Eagle tool online

[tough matrix]

@misty escarp do you happen to have the link?

[misty escarp]

yeah one sec

it can take some finagling and make sure to follow the instructions

https://gfwilliams.github.io/svgtoeagle/

Also, if you're gonna import DXFs into EAGLE don't use InkScape's SaveAs, it's terrible

use https://cloudconvert.com/svg-to-dxf to convert any svgs to dxf (assuming you're starting from an SVG)

I used this method to make ym tarot cards

[distant raven]

This is helpful

I need to get Adobe illustrator one of these days

[misty escarp]

cloud convertwill force you to sign up but i've never gotten an email from them

[tough matrix]

creative cloud is $600/yr, which is pricey

[misty escarp]

oof

[distant raven]

Yeah, maximum oof

[tough matrix]

so I use inkscape...

[misty escarp]

It's pretty good, does what I need

[elder peak]

There's also this: https://github.com/jaseg/gerbolyze

I managed to zap one of my boards after I'd already mostly populated it. I finally found the $5 switching power supply that got lost in my carpet.

I purchased CS4 a buncha years ago and I'm trying to avoid ever giving money to Adobe going forward. Except I also find that I really dislike Inkscape so I have a bunch of workflows that work better if I draw things in Illustrator, save them, then open them in Inkscape, and then import them to FreeCAD or KiCAD.

[ember laurel]

is there a massive shortage of silicon in the world?

[elder peak]

YES

STOCKPILE YOUR MOSFETS LIKE YOU STOCKPILED TOILET PAPER

[misty escarp]

I bought beachfront property just for the sand. I'm gonna be raking it in.

[distant raven]

The chip shortage has led to people developing their own SoCs using p channel and n channel mosfets

Returned to us is the world of room sized microcontrollers

[elder peak]

The out-of-stock notices on my favorite MOSFETs indicate that's not a great idea. 😛

[distant raven]

😂

[tough matrix]

yes: https://www.bbc.com/future/article/20191108-why-the-world-is-running-out-of-sand

[ember laurel]

My customer just signed the contract for my device

[tough matrix]

how large a contract?

[ember laurel]

So I’ll need to get the stuff together - the main MCU is the STM32H750

It’s over a couple of years, all in all a minimum of 500k usd

My MCU has 42 weeks lead time with STM.

The VBT6 version

I can get the IBK, but that’s BGA, and I have everything done for the LQFP

[tough matrix]

42 week!

wow

[ember laurel]

Will probably have to re-do for the BGA 144 pin

[distant raven]

Trying it out and I get a solid lock for my I2C

[pearl tapir]

@ember laurel Have you tried octopart?

[ember laurel]

Yeah of course

All out

[pearl tapir]

These guys claim 12K in stock. Might be BS. https://www.chip-components.com/instcok/2021637/STM32H750VBT6.html

[ember laurel]

Yeah those are BS

I have my Chinese plant looking at sourcing in China

[pearl tapir]

When I need quantity, I usually call the factory rep or product manager and ask them to tell me who has stock.

[ember laurel]

Will do PCB+SMDA+TH in China, then final assembly with case and programming here in .li

[pearl tapir]

Product manager usually knows any where in the world.

[ember laurel]

Good point - I’ll await a reply from the factory, then will give ST a call.

[pearl tapir]

The product manager's job is to move product. The more inventory you take, the more demand.
He will follow the money.

[ember laurel]

If there is an issue I can re-route for BGA.

But I’d rather not, LQFP is kind of nicer to work with for continuous improvements

I don’t have a BGA machine.

[pearl tapir]

I don't like BGA as I can't visually inspect the solder joints and I don't trust X-ray to actually be used regularly.
I would also suggest calling your local Arrow sales person as they have a large presence in China. Explain to him if he helps, he should be able to split the commission. That's worked for me. Also, most people don't know because Arrow doesn't want people to know that they have the ability to do contract manufacturing in China (and can compete with their customers). They have built LED boards for me although I don't know what other boards they might do.

[ember laurel]

Thanks for the tip

BGA is indeed a bit of a pain. I really would like to avoid :/

Plus with zero experience of BGA PcB routing, I’d need to hire someone to check my work.

(Plus time...)

[ivory jasper]

Can someone explain to me why this works? https://tinyurl.com/yjzo8voo Is it just the circuit simulator isn't reflecting what would happen in reality?

[silk lark]

@ivory jasper I think the feather boards use something very similar for switching between USB and battery

I don't understand the explanation for this, but I've heard that an important part of it is the fact that every FET is also a diode

so this is basically a 0-dropout diode

[distant raven]

Yeah, the fet is chosen because at the extremes it operates at for the feather as a switch

[ivory jasper]

Seems if I set Vbus to 4.9V I get current flowing backwards through it

...but if I put a diode there I get unacceptable voltage drop 😦

I need a power selection circuit that doesn't have any voltage drop

(and doesn't use DC-DC boost converters which generate too much noise for my analog circuitry)

[distant raven]

When turn on, it acts as a small value resistor, but when it’s off it is a blocking diode due to the body diode

[ivory jasper]

...and can handle 5V @3A

[distant raven]

Dc/dc boost converters can be filtered if you know what frequency to filter for on power

You can do a high pass filter tuned for 500kHz switching frequency of many DC/DC converters

And filters are pretty easy. Basic ones are just a resistor and either an inductor or capacitor

You can also use an op amp to make a filter as well

Slightly more complicated as you run into the issue of creating a self resonant filter 🙂

[signal topaz]

add some internal resistance to voltage sources, simulators goe crazy when there are zero resistance loops

mosfet need to have some Vds voltage, for current to flow trough it, resistances will make it happen

[ivory jasper]

If I control the P-channel MOSFET from the microcontroller and switch Vbus off when it detects power input on Vext is that good enough? I can setup a loop to do this in under a millisecond. I figure if I put caps in the right places that should be quick enough? Maybe?

The goal would just be to generally prevent current back-flow to the computer that's connected to Vbus

Actually, I bet I could tie it to an interrupt so it's as fast as a few clock cycles (on an 84MHz MCU)

[elder peak]

Ugh, well, I just put in a DigiKey order I wasn't planning on putting in because some stuff was down to really low stock levels. I pretty much had to guess at what the next few months worth of PCB designs are going to look like. :/

[tough matrix]

Got my largest JLCPCB order yet

Bananas for scale - not part of the order 🙂

Remarkably, shipping was only $30 or so

[distant raven]

Oh nice!

More rover wings?

[elder peak]

The first set are octa-gone?

Okay, new milestone in hand-soldering: TSSOP-28, drag-soldered it perfect the first time, every pin connected, no shorts. Magic.

[tough matrix]

no, it is for the logic bits project: https://www.instructables.com/Logic-Gates-Demonstration-Kit/

the boards are small, but each kit has 12 of them, so for 25 kits it adds up fast

[ember laurel]

I’m impressed with the speed of shipping from JLC.

[carmine scarab]

Little known fact I just made up: The "B" in "PCB" originally stood for "Banana"

[distant raven]

Building my cart of Digi-Key for my April boards release. So far... $1090.25 before tax and shipping 😅

I may reduce some of the IC counts to make it a wee bit cheaper

Though I believe I need to still add some things to the cart

[carmine scarab]

Cheaper to register the business than it is to stock it! lol

[distant raven]

Hahah yeah

The most expensive part? The ADCs for that ADS7138 board I’ve been working on

100x costs $584.75

Lol

Otherwise it’s more than $6.50 a part

Single parts for that cost $8

[carmine scarab]

Yikes!

[distant raven]

Total all in per unit cost of the board at 100x quantity of the IC is ~$7.50

If I buy only 50x of the IC it is ~$8.75

Probably closer to $9

And I’m planning to sell it for $13.95, though I may have to do $14.95-$16.95

Especially with ic supply chain problems

[carmine scarab]

Wow, something to be said about volume pricing. Then assembly time, testing, dev, etc.

Tester?

[distant raven]

I’m the tester 🙂

I’ll probably make an i2c test jig for testing breakouts

I need that i2c scanner that @mint moth made 🙂

[carmine scarab]

That's what I meant, test jig/rig

[elder peak]

Welp, I guess I can determine that the DigiKey stock levels are a guideline not a rule.

They had 30 STM32F103CBT6TR's in stock. I uttered words not allowable by the discord and put in an unplanned for order. Order shipped. They still have 30 STM32F103CBT6TR's in stock.

[distant raven]

Hmmm...

Unless it hasn’t updated?

[tough matrix]

I haven't checked recently - are SAMD21/51 boards available, or the shortage got to them too?

[distant raven]

Chips are available but price is going up

Used to get samd21 for <$3 a chip for a single

They are over $3 a chip for single

Haven’t checked samd51 yet but I know they went up

Yeah, more that $5 for a single chip

[tough matrix]

😦

[elder peak]

I've been hearing noises that the entire STM32 lineup has been crunched for quite some time now wheras Atmel availability has been more consistent.

I've got a break-apart board with a Blue Pill clone, a ATSAMD21 feather (Done up my way, which is not deʃhipu's way nor the original feather's way), and a set of accessory boards and so availability suddenly became a concern.

Like, I'm assuming that they are updating the stocking levels on a regular basis, maybe near-daily, but nobody likes to buy something and then get told it's actually out of stock, so probably they just have a well-calculated slush inventory.

No buzzkill worse than having fancy new boards that you can't stuff with parts for an indeterminate future because of availability concerns. :/

[distant raven]

Yeah no kidding

[distant raven]

RP Sapling and CAN Tree boards are here 🙂

A day early too

Gotta order some parts for these, might show them off on Show N Tell tonight 🙂

[elder peak]

All it takes from here is a bit of a CAN-do attitude.

[distant raven]

Has anyone ever sourced sk6812mini (3535 neopixel) from Alibaba or a manufacture?

[tough matrix]

I had sourced WS2812B-MINI (3535 Neopixels) from LCSC
was quite happy with them: https://lcsc.com/product-detail/Light-Emitting-Diodes-LED_Worldsemi-WS2812B-Mini_C527089.html

but never directly from the manufacturer

[distant raven]

Are those actually addressable?

@tough matrix

[tough matrix]

Of course they are
WS2812B is the original addressable LED

[distant raven]

Sorry, just curious because the description was kind of sparse

WS2812B don’t have current control like the newer sk6812mini

Redditer’s report they buy off eBay and AliExpress

But I’m a bit wary of that

[tough matrix]

Indeed, there is no current control

[distant raven]

A step forward in the build process, a solder paste silk screen printer

[fast tundra]

fancy. all the ones I looked at were really pricy so we haven't jumped on one yet

[distant raven]

Mophorn Solder Paste Printer 300x240mm PCB SMT Stencil Printer High Precision Solder Paste Aluminum Work Table XYZ Axis Manual Precise Screen Stencil Press Printing Machine https://www.amazon.com/dp/B087LTMHRY/ref=cm_sw_r_cp_api_glt_fabc_W4RVT677YXMVZSFPNSE8?_encoding=UTF8&psc=1

@fast tundra this is what I got

[fast tundra]

ooo that's not too bad

[distant raven]

Granted it was $64 when I hit the buy button

[fast tundra]

We did just buy a huge ultrasonic cleaner, though haha

[distant raven]

Haha, I’ll eventually get one of those

[fast tundra]

Pretty sure one of my sisters is going to kill me because of all of the industrial equipment that keeps appearing here as Winterbloom grows.

[distant raven]

I just ordered some steel laptop desk stands to cool PCB on

Cheaper than buying a half sized wire shelf lol

I’m feeling pretty lucky to have had 22 orders in 6 months, so I think things are starting to trend up. I wish I was making more at my day job to bankroll my business more

It’s a fine balance between providing a place for my family and working enough, but also having enough time to do business stuffs

[fast tundra]

I just left mine

[distant raven]

Eh, Google was a bad fit for ya

You seem much happier doing Winterbloom shenanigans

[misty escarp]

nerve making for sure, good luck!

[distant raven]

My job is okay mostly because it pays the bills and got me off the east coast

Now it’s just working my way up and growing my business at the same time. And also being strategic with how I divvy my time

[fast tundra]

yeah it's tough to balance

[distant raven]

I’m kind of surprised you stayed so long with Google. Once upon a time I wanted to work there

I thought it would be fun working for a company that seems to employ some of the smartest people

But I realized the smartest people left Google after they realized they could be more themselves somewhere else

And mostly what you get left at companies like Google, Facebook, etc... are weirdly egotistical maniacs who like to dump on people.

Not saying there are not good people at those companies, they just either leave or are pushed out

Anywhoodles

Glad you’re doing winterbloom full time @fast tundra 😃

[fast tundra]

semi-full time.

I'm hard-limiting the amount of time I spend on it for mental health reasons. 🙂

[distant raven]

🙂

Makes sense

[elder peak]

I figured I couldn't cut it at google when I was a wee lil' Wirehead.

Then I interviewed there and decided it was probably a crappy place to work.

Then I interviewed there again for interviewing prep, except they couldn't get me in so I interviewed there the day after I'd already accepted an offer elsewhere after biking to the plex in the rain.

Lately I just say "no, I can't ethically work there" even though I have a blanket policy of not harassing recruiters.

So, yay! You successfully cut it at a place that is too cool to have me, Stargirl and then escaped with enough of an ability to do something actually cool, assuming your sisters don't kill you for the industrial equipment.

[fast tundra]

I do fear for my life

[misty escarp]

get a big dog! You get lots of pets and protection

[elder peak]

But... the cleaners. They were a ultra-sound idea.

Not just a sound idea.

Also, OMG, it's absolutely not in the slightest bit a surprise given things that your test rig would be as pretty and colorful as the rest of the Winterbloom modules.

[bright thistle]

asking here sinceit's PCB related, sorry if I'm in the wrong place 🙂

can anyone confirm if Molex SL 171971-0003 mates with 50-57-9403? 🙂

[distant raven]

I’m gonna be Frank with you for a second... I’ve never used those connectors in my life (as far as I know) okay now I’m Seth again

Might be the longest board development for me

And yet it’s only 3.75” long. 95.3mm for you normies out there

[misty escarp]

IDK if my tarot cards count but they were 5" x 3"

[distant raven]

That’s a pretty good size

The panels for my upcoming boards are sizeable

If I just ordered the panels from OshPark (not a medium run) it would cost anywhere from $59-$98 depending on the panel

Medium runs on the other hand run about $11-$17 a panel

[fast tundra]

5"x 3"!

(my biggest PCB is just under that size)

@distant raven if you're doing full panels it's probably worthwhile to skip OSHPark and go straight to a fab

[misty escarp]

let me dig up a picture

[fast tundra]

you can get quotes from a bunch via Digi-Key: https://www.digikey.com/en/pcb-builder/

[distant raven]

They’re mini panels

3x4/3x5

I just don’t have the volume to justify larger panels and larger orders that some US fabs want

[fast tundra]

fair

We stick largely with PCBWay for bare PCBs.

[distant raven]

Plus $1 per square inch isn’t terribly expensive

[fast tundra]

yeah

[fast tundra]

so pretty

[distant raven]

I’m still getting most 2 layer boards for $1-$2 per board. Worst expense right now is parts

[misty escarp]

happy to share the files if you want to make one!

[distant raven]

I’m making an ADC breakout and I’ve got to buy 100+ to get the price right

[fast tundra]

Data converters can be super pricey

[distant raven]

Yeah

$8 for a single, $5.84 for 100-499

[fast tundra]

A previous design of ours used a $15 DAC (at scale)

[distant raven]

Those and samd21 are my biggest chip expense

Currently

That’ll change when I roll out these same51 boards

[fast tundra]

Depending on the quantity you can sometimes get a better deal if you buy direct from microchip instead of through a distributor

[distant raven]

Yeah

I think if I get past selling 200 units of these CP Sapling Rev B, I may try to buy direct

[tough matrix]

Just checked that I had 23 orders on tindie in the last 5 months. We are close 🙂

Plus the RoverWing campaign....

But K have no intention of making it more than a hobby. At least.. not yet

[heavy jasper]

@bright thistle A very late reply, but: Yes, at least as far as Mouser is concerned, based on the "mates with/use with" comments. Make sure you use also the recommended terminal series (the "use with parts" on the connector side) and if you're using specifically tin-plated 1719710003, also get tin plated crimps as well instead of the gold-flash ones. (dissimilar metal contacts can lead to a variety of interesting failures that I'm happy to find and link to some docs for if folks are interested). If you can afford it (it's a huge splurge) the correct hand crimping tool (538-63811-8700 at the distressingly 'reasonable' price of $362.5) is also advised if you're going to make a bunch of these or you care about very long-term reliability. Otherwise you can likely get away with some generic crimp tools.

[distant raven]

My next order might be a bigger one of 100+ units. It’s not confirmed quite yet because they haven’t paid the bulk order invoice but it’s a nice bulk order

[bright thistle]

Fret not, at least with discord I can read messages later, as opposed to IRC :D

Thank you for the heads up about using different metals, didn't know about it!

Err... No, I don't think it'd be possible to get the official crimp, but I'm not crimping many contacts anyway X3

Thank you for all the hints, I'll post the PCB as soon I decide if I'll keep the JST XH-B*B-A-M, or just use the -A ones (apparent low availability)🙄

[tough matrix]

@distant raven nice!

@heavy jasper I am indeed curious - how much of a problem is mating tin-plated contacts with gold-plated ones?

I know that when wiring a house, connecting copper to aluminum wiring (sometimes found in older houses) is dangerous if not done right. But about mating tin and gold-plated, I know nothing

[distant raven]

Basically comes down to the electrical properties of Tin vs Gold. Electron stripping is part of the issue. Which I believe can eventually cause fires

[ember laurel]

aluminium is quite difficult, since it oxidizes in about 20 seconds in plain air

aluminium oxide isn't conductive..

[misty escarp]

fun trivia, I think aluminum oxide is what rubies and emeralds are made of?

[unreal flax]

Ruby, yes, but emeralds are different.

[elder peak]

So, connector material tin be a problem.

But the real problem wasn't that aluminum wire would burn down houses, it was that, when the fire investigators came, all aluminum would say was "I DIDN'T DO IT! YOU DON'T GOT NOTHIN' ON ME COPPER!"

[misty escarp]

I was thinking of sapphires

[misty escarp]

Corun-dumb puns are what I live for

[elder peak]

It's OK. Remembering it is a real corundum

[misty escarp]

ayyy

[elder peak]

Wow.

[misty escarp]

great minds

[bright thistle]

working with a Pi, are 22 AWG for power and 24 AWG for data acceptable?

[tough matrix]

24 AWG for data is fine (in fact, most people use 26-28 AWG ).
22AWG for power should work too

[bright thistle]

thank you 🙂
it was for putting the correct crimp terminal in the BOM 🙂

using 22/24, I can order a bunch of the same ones with the same gauge range 🙂

[tough matrix]

makes sense

[bright thistle]

and I'm finally done with my first PCB, ready to order 😄

[fervent lance]

Hi guys

Does someone here understand basic electronics?

[bright thistle]

tracks 0.5mm clearance 0.3mm

[misty escarp]

it's usually advised to just ask your question so everyone can see, and anyone who can help likely will 🙂

[fervent lance]

Ok

[tough matrix]

@bright thistle what connectors are you using? are these JST XH?

[bright thistle]

Molex SL 😄

XH are 2.5mm pitch, on the other side there are 2.54mm pads, and I don't want to mix 🙂

plus latched connectors 🙂

the board is just for "grouping" a bunch of Adafruit 1374 and 1375, so I don't have to run many cables around 🙂

[tough matrix]

looks good

[bright thistle]

^_^

I'm also trying to design a PCB for a tube theremin, but I'd rather leave it for when I have better expertise XD

[elder peak]

Yeah, you don't want an elaborate PCB design to go down the tubes because you made an easy mistake.

[misty escarp]

Lots of lessons to be learned theremin tho

[bright thistle]

I'd be turning an existing open air scheme into a design, if it'd make things easier

But things like trace width, ground planes and whatnot, I have to look them up further :)

[elder peak]

• taps "Master Punner" role *

[bright thistle]

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Oh!