#help-with-hw-design

1 messages · Page 45 of 1

distant raven
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Be careful, it’s definitely a slippery slope

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🥸

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Curious what your background is ?

pale current
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Comp sci, and just hobbyist interest in electronics

distant raven
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Very cool, I studied Computer Engineering but you’ve probably seen me post about that a lot, ha...

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I will say that the hardware side is much easier for me, even though I can write software

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I’m having to learn to be better at software development for my job because I’m an embedded engineer

pale current
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I grew up on the C64 and ended up doing some driver / network development got used to that level above hardware level to a degree

distant raven
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Oh C64, interesting

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My first exposure to programming was 2010

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Visual Basic

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I didn’t learn much in that

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I wrote chat bit scripts for a while for IRC chat rooms

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Mostly developing games for chat bots

pale current
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Yeah I've been doing this for a while now, the C64 dates me ha. But the hardware side is still fairly new and interesting to look into

distant raven
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Hardware is newish for me

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I actually started right around this time last year

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In terms of doing circuit and PCB design

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At first I made an LED sign for which I wrote some animations for in arduino

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Simple state machines for that

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Then I decided to make my own Arduino

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Which lead me to work on an MSP432 feather, and designing hardware for a Visible Light Communication project, then designing most of what I have on my shop

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Slippery slope

pale current
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Sounds like it! So far it should be fun knowledge to play with

distant raven
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It’s probably one of the best things I learned how to do

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It also made me a bit sad to think that so much of the skills for making hardware just died out for so many people and with that, so did the jobs locally

unreal pollen
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What layer does text usually go on for identifying I/O ?

tough matrix
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tPlace

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and bPlace, for bottom silkscreen

unreal pollen
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Is place supposed to reference something like "component placement" ?

tough matrix
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of course, in practice all that matters is what shows on gerbers, and gerbers have just one silkscreen layer on each side of the board - so whether you choose to put some markings in Eagle in tName or in tPlace is your choice - as long as both of these layers are exported to silkscreen layer in gerbers

distant raven
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A Nano board I made being permanently installed as a neopixel controller for like 10 neopixel

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Basically going to push a button a change the color based on if I’m busy or not lol

ember laurel
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how do you guys do edge plating of boards?

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I found this on PCBWay

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would that be enough for most fabs, you think?

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(along with a note that you want your board with side/edge plating)

distant raven
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Edge plating is usually something you specify according to what I’ve found googling

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That’s related to Eagle, but I think it applies in general

heavy jasper
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Minus the arrogance of the individual in that thread; what they're saying is generally correct in that if you run the copper out past the edge, it will work and be able to be connected. However the key factor there is in knowing that the board house isn't going to silently say "oh this engineer accidentally put copper outside the lines, let me pull it in away from the edge for them," especially for more automated/no-touch houses. That's where the fab drawings become useful to say that the edge-connectivity is intended (or to ask for full edge-plating in your case).

unreal pollen
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next challenge is to make a doubler for this, which looks like it will require routing on the top and bottom

last bison
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I started designing a feather wing for driving a cheap 2.1" round touch screen based on lt7688. It's my second design ever so it probably sucks. But it's only 2 layers. The routing looks really bad 😂.

✖️ have I missed any connections?

✖️ Is the 3-wire spi to the screen from the feather correct?

✖️ Should I add backlight ctrl from lt7688?

✖️ And finally would it be better to hookup the screen spi directly to the lt7688 chip instead of connecting it to the feather? The spi to the screen is only used for initialising it in the begining.

Eagle files and datasheets is available on my GitHub
https://github.com/manmountain/oTFTeatherWing

GitHub
manmountain/oTFTeatherWing

Contribute to manmountain/oTFTeatherWing development by creating an account on GitHub.

heavy jasper
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It seems like clocking requires either a 32KHz crystal and some loop-back clock from an internal PLL, or 32kHz+10MHz crystal, and I don't see either in the schematic?

last bison
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I think it have a internal clock at 72Mhz but supports a external clock at 32Khz external

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That's why I connected pin 0 and pin 80

heavy jasper
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Hm, so the internal clock does seem to be there, howevere it does seem to be in just the MCU section

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figure 1-1 still seems to show that the MCU section then drives a PWM output that goes over to XI in the TFT controller section

last bison
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Hm, yes I don't really get that part :)

heavy jasper
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It may be that there's either two dies internally, or just two relatively separate logical chunks inside the chip.

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I'd have expected maybe some internal clock mux or something that lets you select a divided version of the internal clocks to use for the TFT controller, but that's not the case, so instead you have to set up the PWM peripheral (it seems, PWM1[2]) in the MCU section to generate an external 8-12MHz square-wave, then externally loop it back as a clock input of the TFT section

last bison
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I asked leveltop about the clock part.

heavy jasper
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If you're in communication with them, you may as well also ask for the reference design files

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(on the website they're listed as available by emailing their sales department)

last bison
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@heavy jasper I got a reply.
"There is no need to connect external crystal oscillator. Crystal oscillator is provided inside LT7688. To connect XI and XO  with resistor is in order to form the required crystal oscillator circuit."

heavy jasper
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I’m a bit suspicious of that answer; it seems like it disagrees with their datasheet. Can you get their reference schematic and see what they’re doing there?

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At this juncture I’d advise at least putting down the pads for an external connection between the pwm pin and XI. You can no-pop it to start if you like, but it’s good to have the option. If you have space possibly put down pads for an external 10MHz crystal and caps too, if you want to have all the options.

supple pollen
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My reading of that sentence is that the chip provides the crystal oscillator circuitry, but not the crystal.

fervent lance
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I have a question regarding 4 layer routing

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This is the default drc setting for 4 layers on EagleCAD, I uploaded an image a while back with a different setting, should I use this or should I use that?

📎 unknown.png
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this is the setting in question

distant raven
fervent lance
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JLC is my preferred fab house

ember laurel
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@fervent lance JLC specifies that on their capabilities page

distant raven
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Yissss

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Going to build two of these babies up tonight

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Hopefully test them as well

tough matrix
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what does it do?

distant raven
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@tough matrix a VLC cape for a beaglebone black

fervent lance
heavy jasper
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I'm guessing altimeter for model rocketry?

fervent lance
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yes

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any mistakes

heavy jasper
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What's U$25?

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Some kind of ideal diode or something? (it has +/-, and without it you're back-powering the USB port which it seems like you don't want)

fervent lance
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its a 500ma fuse

heavy jasper
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Okay, so in tha case you are definitely back-powering the USB bus out to the computer if you were to plug in both the 12V and 5V at the same time. (and also quite possibly back-powering the 12V rail through U4 if you only plug in the USB)

fervent lance
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this is the fuse

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the mcu is circuit is basically the teensy 3.2's

heavy jasper
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Any thoughts re: usb comment above? Continuing to look across the design in the meantime.

fervent lance
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I didn't quite understand the usb comment

heavy jasper
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I assume the micro-USB port here is so you can connect it to a computer to program

fervent lance
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yes

heavy jasper
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Normally in that arrangement, the computer is providing its own 5V power

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Here, you have that VBUS connected by a fuse to your own 5V rail, that's being generated by U4 from 12V

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so you're potentially forcing power back into the computer (which is not desired)

fervent lance
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oh

heavy jasper
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Or in the case where you run without external 12V, then 5V will come from the computer and actually run backwards through your buck converter (U4) due to the buck converter's high-side MOSFET body diode, so your "12V" rail will be powered, with something a bit less than 5V

fervent lance
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the usb port is only there to transfer code to the mcu

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once that's done it will be powered by a 9V battery

heavy jasper
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To simplify things, you could potentially just disconnect VUSB entirely

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and then always power the board via your own supply, and plug in the USB just to program

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Regarding your buzzer: the datasheet for it is a bit confusing. Operating voltage of 25Vp-p, but rated voltage of only 3V Vp-p?

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And to confirm: you do realize that it's just a piezo element, not including a driver, so you do need to actively drive it at its rated frequency (I see its on a PWM pin so i assume this is what you're going for)

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Nit: The DMN305 used for pyro output appears to be no longer recommended for new designs; they recommend the DMG3402L instead.

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Big problem: C9 is misplaced, it should be in parallel to R24, connected from your buck output voltage to your feedback voltage. Currently it's coupling noise from your switch node directly into your feedback node which would probably drive it unstable.

fervent lance
heavy jasper
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Yep, that's it.

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Question: Do you have a transponder/beacon in the rocket this is going along with?

fervent lance
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no

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I'm not doing any communication stuff with this pcb here

heavy jasper
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I can tell nothing with this PCB, but is there a separate transponder also in the same general payload/area?

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(aka is there a source of large RF interference nearby?)

fervent lance
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no

heavy jasper
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Okay. If there was, would have suggested dropping the values of those divider resistors (and R15/R16) by an order of magnitude or so to make them less susceptible to noise.

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In either case, I'd recommend adding a filter cap to the VOLTAGE node you can filter out any transients on the battery pack and make sure your ADC can keep up (anti-aliasing).

fervent lance
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that's why I have all those output's

fervent lance
heavy jasper
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It depends on how fast you're going to be sampling that pin. But given it's just a slow battery voltage reading, you can hit it with a pretty heavy hammer (e.g. 100hz or less corner frequency of the filter).

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I'd probably go 100K/10K for the divider, and then since the thevenin equivalent resistance of that divider is (10K || 100K) ~= 9K, and you want ~100hz corner frequency, 100Hz = 1/(2pi9000 ohms * x Farads), that solves out to ~176nF. So probably anywhere from a 100nF cap to a 220nF cap will do just fine.

fervent lance
heavy jasper
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This would couple only the noise through to the ADC. You want to low-pass filter, so have the cap run from VOLTAGE pin to ground.

fervent lance
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would the cap have to be a pulldown

heavy jasper
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Here, yes. (since GND is the fixed voltage, not the moving one that you want to filter)

fervent lance
heavy jasper
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That'll work

fervent lance
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now about the buzzer - does that mean I need a fet to drive it

fervent lance
heavy jasper
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I'll be honest: I'm not sure if I can make a judgement on the buzzer based on the available datasheet. Its operating current is only 5mA, which should be fine for a GPIO to drive, but more so their "recommended" voltage seems to be nearly an order of magnitude higher than their "maximum" voltage

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so there's a typo somewhere, and if the typo is the wrong way you'll be driving with far less voltage than it needs to work

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Something I'm not going to check in great detail, but good to verify/document on the schematic on your own: Make sure that the I2C devices have different addresses.

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(it's nice to put on the schematic to have as a reference when you're writing code, and especially nice if someone else is ever writing code for something you designed)

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If you have space, you might also consider a big electrolytic capacitor on 12V

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given that the pyros will draw a rather substantial pulse of current

fervent lance
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what's the address for my H3LIS331 accel

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nvm

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any mistakes with any of these sensors?

heavy jasper
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I unfortunately don't have time to super dig in (definitely not to the level of verifying pin numbering, for instance) but nothing obviously wrong that I could see.

unreal pollen
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todays adventure on "fun with vias"

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Question though, I'm having trouble getting the board outline done nicely. The tools for drawing those lines are extremely primitive compared to 2D CAD for drawing shapes. How do ya'll draw nice shapes at sizes you want for the overall board outline?

distant raven
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Is this Eagle?

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You can import an SVG to the outlines layer, or you can use the line tool

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The lines tool should give you various options for how it handles corners and angles

unreal pollen
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I didn't see any line tool options anywhere, just your basic line or curve commands. Yeah this is EAGLE

ember laurel
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What would you consider an acceptable fsw output ripple for a switching buck?

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I’m dropping 32V to 5V.

rain remnant
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fusion 360 get more and more pcb things

distant raven
unreal pollen
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Is a mounting hole in the corner of a board typically a via? Or how does one normally add those?

distant raven
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Yeah

pearl tapir
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I create a specific part for a mounting hole so I know the size and whether it is plated and then put it on the schematic. Then it can either float or be tied to a net. Often tying a net such as GND to a conductive case is a bad idea.

tough matrix
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there is a whole library of mounting holes.
Or, if you do not need plating, you can just use "hole" tool in Eagle.

amber raven
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right, excuse me, is there a way to turn a schematic and a board design into a part in eagle?

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im currently in need of the INA219 current sensor breakout board part in eagle to design a pcb and all that's available is the board and the schematic for the breakout board itself and not a library

fervent lance
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@heavy jasper any buzzers with a wide user base you suggest?

heavy jasper
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A quick note first: In general, absent a previous discussion directly before, please don't ping community helpers on the thread when you need help (it rapidly becomes unmanageable if everyone does, and the mods tend to frown on it). Just posting is good, and we'll get to it when we can.

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That said, the digikey search magic here is under "alaerms, buzzers, and sirens" there's an option in the parametric search for "indicator, internally driven" which I think is what you're looking for (doesn't need external drive, just makes sound).

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Then you can sort by "Voltage Range" for any parts that include 3.3V

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This search seems to be a good combo of stuff you want (constant tone, 3.3V supported, internally driven, surface mount): https://www.digikey.com/en/products/filter/alarms-buzzers-and-sirens/157?s=N4IgjCBcoGwJxVAYygMwIYBsDOBTANCAPZQDaIALAAxwDMdIAuoQA4AuUIAymwE4CWAOwDmIAL6EKAdgqIQKSBhwFiZELVoyKEQrSpTaAJgjMQ7TjwEjxhAKy0AHHIVK8hEpHLU9U201YckNx8QqISILbwzmhYbqqe6mAUDlQgunBScDBp6nAOtDqUtlm0OfQOFTn2hpFVRjCF1VKGdYZRdkYOfh2GWVVZDTlgxhSGUkMjeRNJDtmEw2C2NEPwjqXzq3CFYJtz4PDULRtw1Hs7J2DbB8YrJ3q3FBoPxTnSa2cHME7H0h8nDkd9v9ZPMDDU-KZzEFLKEbCAHJdoopYioPF4wI4av4zIFglYwvNykjXKi1LRbF0KAhIbiYdYxOFstAQPwACacAC0YCohShIByAEc2ABPTiFEUsXCcdDYFAMoA

Audio Products | Alarms, Buzzers, and Sirens | DigiKey

Audio Products - Alarms, Buzzers, and Sirens are in stock at Digikey. Order Now! Audio Products ship same day

fervent lance
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I'm sorry, will keep that in mind

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would I need a mosfet to drive it?

heavy jasper
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It's probably a good idea, and easy since you have some good ones already

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Maximum current single pin limit for the MCU is 25mA

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and the buzzer is ~30mA.

fervent lance
heavy jasper
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yeah

fervent lance
fervent lance
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is this right btw?

fervent lance
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ok

ember laurel
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@fervent lance you may want to put a resistor between your BUZZER and GND, to avoid accidental turn-on due to noise.

fervent lance
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ok

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10k?

ember laurel
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That MOSFET only requires 6nC charge

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you can put something higher... I usually do 24k ish for these

fervent lance
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24k for the buzzer

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ok

ember laurel
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and perhaps an inline current limiting resistor as well for the gate

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just something small

fervent lance
ember laurel
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should be ok yeah - but put a gate inline resistor as well

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100 ohm or whatever

fervent lance
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100ohms

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copy that

ember laurel
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I guess you dont care about timing here?

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IE, are you PWMing this?

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or is it some kind of DC buzzer?

fervent lance
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it's a magnetic buzzer

ember laurel
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looks good yeah

fervent lance
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this one

ember laurel
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that'll give you 3.3/100 = 33mA gate charge

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perhaps up it to 1k

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so 3.3mA

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that'll give you 6nC/3.3mA = 1.8us

fervent lance
ember laurel
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threshold voltage is 1V, so your actual rise time will be more like 303ns

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looks good

fervent lance
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and does everything else in my schematic look right?

ember laurel
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I didn't check it

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let me have a quick look

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probably switch that mosfet to a DMG340

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DMN305 is deprecated

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or an AO3400

fervent lance
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nah

ember laurel
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(cheaper, same specs)

fervent lance
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I'll stick to the dmn305

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I have a couple lying around

ember laurel
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yeah if you got em, doesn't matter really

fervent lance
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I'll make the switch with my next pcb

ember laurel
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not the most crucial component 🙂

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What's L1 value?

fervent lance
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6.8uH

ember laurel
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I don't see any caps after the buck

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except the small 47pF

fervent lance
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the 47uf is the 2 22uF's

ember laurel
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how much current will you be drawing from that 5V line?

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ah sorry, going upwards. I see.

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that inductor has quite a high DCR of 95m

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you should be able to get something in the 20m range for that one

fervent lance
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ye

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I'm mainly worried about the voltage regulators, the buzzer and led and the main sensors

ember laurel
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ok you're not pulling much current

fervent lance
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everything else is from an old schematic the

ember laurel
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your LDO is 600mA

fervent lance
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yes

ember laurel
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your LDO has a pretty bad PSRR at the switching frequency of your buck

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not even specified

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buck is 500kHz

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it should be fine, but since you're not drawing much current, perhaps pick a larger L1

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going to 10uH should give you half or 1/3rd of 500k ripple.

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ensure you use X7R caps on the LDO output

fervent lance
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so both the 10uF and 1uF that i have should be x7r's right

ember laurel
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yeah

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you want low ESR there, check datasheet of LDO

fervent lance
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any specific 10uH inductors

ember laurel
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what size constraint do you have

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you don't need that much current though

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35m 2.2A should be ok

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$0.25

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your LED mosfet - why not use the same as for buzzer?

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that MOSFET config looks a bit strange to me

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for the WS2812B

fervent lance
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it's for level shifting

ember laurel
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mm yeah ok

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do you need any speed there?

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or is it just a slow signal?

fervent lance
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it doesn't have to be fast

ember laurel
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ok

fervent lance
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what about the main sensors?

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any mistakes there

fervent lance
ember laurel
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I just saw on the datasheet that it is not recommended for new design - rather use DMG340x

fervent lance
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no I mean't because I already have em

pearl tapir
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You can get substantially more volume from a piezo buzzer by driving it differentially.
If you use one that has a Helmholtz resonator, I've found that sweeping the frequency a small amount around the data sheet stated resonance to insure that is hits resonance works well and to my ears is more noticeable. The resonant frequency is not typically a precise number but a range.

heavy jasper
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In this case the buzzer has an internal driver, so just need to provide and remove power.

pearl tapir
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@heavy jasper I understand. Just describing one of my designs that was sold commercially for several years. A beeper, a 9V battery and a 4069.

It was a very loud beeper that went inside a ball that visually impaired kids could play catch. It could be heard across a soccer field.

fervent lance
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Mr. Hepburn. ;)

distant raven
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this will be by far the most complicated board i've ever made

heavy jasper
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USB-A, ethernet, and what seems like a COM express module though the headers are too far apart, so some other SOM?

carmine scarab
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RPi4 Compute mating board?

pearl tapir
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And Pico I/O?

distant raven
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Compute Module 4 carrier board with some other fancy stuff

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There’s a lot more coming to it, and it will likely be one of two or three variants I’m trying

carmine scarab
vapid grove
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Hey @distant raven what features will you add on your cm4 carrier?

frozen sinew
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Hey! Trying to create my own Arduino pro mini, but how would you make it programmable when the PCB is finished?

haughty wolf
# frozen sinew Hey! Trying to create my own Arduino pro mini, but how would you make it program...

the pro mini doesnt let you programme the board from usb directly, you would need a usb to serial converter like this: https://www.ebay.co.uk/itm/FT232RL-Board-FTDI-USB-to-TTL-Serial-Adapter-Module-Port-Electrical-Part/192745957468?hash=item2ce08de85c:g:t~sAAOSw7R9cBNlH
there are plenty of youtube videos showing you how to do it

eBay
FT232RL Board FTDI USB to TTL Serial Adapter Module Port Electrical...

RXD/TXD transceiver communication indicator. Module size:36mm(length) 17.5mm(width). 1x Module.

distant raven
haughty wolf
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its cool to see people doing stuff with the 2040 already. i just wish pic had taken off in the same way haha

frozen sinew
unreal pollen
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Completed and ordered my itsybitsy prototype stuff. I know there aren’t any components and it’s just a bunch of vias, but this was pretty cool to make, can’t wait to keep trying harder things. Thanks for your help everyone!

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Next I think I’m going to try to put the lipo charging circuit in this form factor instead of having a breakout.

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I would assume those parts are easy to come by but I have no clue on what companies do the full assembly work like that. Any recommendations?

haughty wolf
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@frozen sinew if you install minicore onto your arduino ide then you can programme many different atmel chips without a bootloader, and loads of other options

📎 unknown.png
frozen sinew
haughty wolf
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that alright! sorry for the late reply, i was in the bath lol

tough matrix
# unreal pollen I would assume those parts are easy to come by but I have no clue on what compan...

A lot of them.
It all depends on how many boards you need.
From China, JLCPCB is the easiest to get started and the cheapest; you can order assembly of as few as 10 boards at reasonable price. However, they have limited part library, and there is no way to add a part not from the library. Other common Chinese fab houses doing assembly (also referred to as PCBA) are PCBWay and Seeed Studio; there you can add any part in existence in the universe, but there is a significant setup fee, so doing just 10 boards would be expensive.

Doing assembly in the US is typically more expensive; I know @distant raven recently was looking into this

distant raven
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I’m contemplating setting up contract manufacturing

distant raven
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One of the first PCBs I etched last year

frozen sinew
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It looks like I need to use two pull-up resistors to use the I2C bus on the ATmega328P, but I'm not sure what resistance I should choose.

📎 unknown.png
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The minimum resistance seems to be around 970 Ohm, but I don't know how to find the maximum, and what I should take into consideration

📎 unknown.png
distant raven
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4.7K is a good value

frozen sinew
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Sorry for posting in the wrong channel btw, I see that now

frozen sinew
distant raven
frozen sinew
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I think I get it now. I have used the Pro Mini and I2C with MPU6050. I thought the pull-up resistors was on the Pro Mini-board, but I see now they are on the MPU6050 module! And that is exactly 4.7kOhms

carmine scarab
# distant raven

Regardless the level, there's just something so inherently pleasing about some etched copper

distant raven
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oh i know. it's super fun

tough matrix
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Never did etching PCBs, but I remember what fun it was to do wet photography when I was a kid. mixing your own chemicals, developers and fixers.. and seeing how the image appears under red light when you put the paper in the tray of liquid.
It was magic. However, to be honest, my prints were quite lousy compared to what I can get today on a decent inkjet printer, never mind professional photoprinters.

distant raven
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I used a PCB mill for etching

haughty wolf
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thats cheating!

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if your hands arent stained brown by the end of it youre doing something wrong lmao

waxen crystal
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Far better than digital in my opinion :P

elder peak
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None of you are real developers. Real developers are chemical compounds that link to sensitized silver halide crystals in a gelatin matrix to make the pattern of photons that hit the film visible.

waxen crystal
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Exposed, we have been

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(pun intended)

haughty wolf
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hahaha

distant raven
vapid grove
#

Congrats!

distant raven
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What’s great about the new CP Sapling is if you put stacking headers on it, the LiPo power pack will sit perfectly on top of it

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One of those things I didn’t realize when I did the redesign

haughty wolf
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theyre pretty

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what's up with the one on the left though?

distant raven
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Reflection making it look off

haughty wolf
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ah i see
thats the after dark finish isnt it?

#

i cant really justify buying from osh park considering how much more expensive it is
well, that and i dont live in america lol

tough matrix
#

@distant raven it is a beauty

distant raven
#

The afterdark finish is amazing

#

There’s just something so sleek about it

silk lark
elder peak
#

Yeah, that looks like it would LED to trouble.

silk lark
#

need to program it now and see if half of them doesn't work

waxen crystal
distant raven
#

Here

waxen crystal
#

Cheers -
I'm making a footprint for an SMD mounted Pi Pico in Eagle, I'm not really sure how big I should make the pads for them to be of any use

📎 unknown.png
#

Should I make this longer on the left?

heavy jasper
#

(since there are also some subtleties about holes for USB connectors and such

elder peak
#

...so doing it blindly would get you in a hole lot of trouble?

waxen crystal
#

Thanks!

charred island
#

Hey All! I was wondering if someone could help me with some Kicad questions

#

My issues are really finding symbol/footprint libraries for generic components I find on Amazon

round stump
#

What components?

charred island
#

logic level converter, rtc, ssd1306 oled

#

I ended up cobbling them together from the sparkfun libraries, but it was way harder than I was expecting

#

do most people just make their own symbols/footprints?

round stump
#

I'm not sure about most people but I tend to find libraries of components that others have made for my projects.

#

For me, I use a lot of through hole components so I can just use header pin holes for most of my stuff

charred island
#

okay, that makes sense

tough matrix
#

for most "standard: components - passives, IC chips, connectors - KiCad shoudl already have them in their libraries. But I am no KiCad expert, I mostly use Eagle
If you can't find it in standard libraries, looking on UltraLibrarian on SnapEDA.
If everything else fails.. then yes, make your own symbol/footprint

brisk spire
#

Q as for some reason my brain is arguing with itself- Correct or should be reversed? I thought convention was pin1 GND but seemingly there is no convention anymore 🙂

📎 unknown.png
round stump
silk lark
#

I find that Fritzing is pretty easy for artsy PCBs

round stump
#

As opposed to Eagle or KiCad?

#

oh

#

My initial message was bad.

#

I should have been more clear whoops. I was trying to make my first art PCB with KiCAD last night. Definitely weird to not be doing things with right angles and such.

silk lark
#

kicad was really not designed for this

round stump
#

But Fritzing is?

#

Or just more user friendly 😛

silk lark
#

it's closer to this use case, Fritzing is really not user friendly when you have more than 10 parts on the board, especially in cases like changing the value for 30 resistors for LEDs or such

#

but it's based on SVG internally, so it pairs with Inkscape very well, and lets you do arbitrary outlines, bezier curve traces, etc.

#

also lets you make the pcb without a schematic

#

and pick which pins to use for what as you go, instead of having to commit beforehand

round stump
#

Oh cool. I shall check it out

twilit mango
#

@round stump What OS are you running?

heavy jasper
#

I think generally if you think about this as "mechanical control outline" you're probably using DXFs and would be better served by Kicad. If you think about it as its own form of expression and want to have a greater variety of options to make it look nice, then svg is probably the way to go.

#

(I don't have a ton of time in Kicad; Altium at least will let you import DXFs and use them as things like copper pour definitions, board outlines, etc. But generally DXFs tend to be quite rigid since they generally come from the CAD/GD&T world)

twilit mango
#

@round stump If it's MacOS, ping me. I dug up a more recent build of Fritzing than is available for download from an obvious place. I can send you the dmg. If it's not MacOS, disregard. 🙂

round stump
#

I am on windows but thanks for the offer!

#

@heavy jasper That's an interesting way to think about it

round stump
#

uh oh, I've figured out how to make kicad do terrible things

#

😬

elder peak
#

(This is mostly because Inkscape's UI never quite works for me)

silk lark
#

I used to work a bit as a graphic designer, so I'm very familiar with Inkscape, which helps a lot

twilit mango
#

@silk lark I imagine so! I'm feel like a complete idiot trying to use Illustrator (or Inkscape really). I don't understand SVGs at all. I have to create parts for Fritzing objects, and they're always just a lot of rectangles or circles. They turn out ok most of the time, but if you ungroup the part and look at what makes it up, it's clearly made by someone who has no clue what they're doing. Unlike the parts from PhilB that end up looking amazing. Like actual parts.

round stump
#

I made the resistor in the logo be actual resistors and then scattered LEDs throughout the P

#

Going to start again from scratch but I have a rough idea of what I want to make now

twilit mango
#

Nice!

round stump
#

Thanks! Also I kept trying to add a via on a SMD pad. In my several years of PCB design I've never done SMD before. That was a confusing moment lol

silk lark
#

@twilit mango I find that it helps if you think about it not as a drawing, but as a sort of collage, made up out of basic geometric shapes, which you add up or subtract, kind of like making pictures out of pieces of colored paper

twilit mango
#

Hmm. Fair enough. Maybe I'm not doing it quite as wrong as I feel like I am.

silk lark
#

or like a scrapbook I suppose

#

that;s for sure, you always judge your work more harshly than it deserves

#

it's normal

round stump
#

passes all design checks too 😄

fervent lance
#

How would you decrease the size of a bmp made in photoshop on eagle

distant raven
#

I’m about to buy 5000 4.7kOhm resistors

#

0603 size

#

Lol

light ermine
#

I'd just buy one 24 Mohm resistor

distant raven
#

😂

distant raven
#

5% tolerance is okay for pull up resistors, yeah?

#

Yeah okay

#

So 5000x 0603 sized 4.7k resistors and 5000x 0603 sized 10k resistors

#

50x 3.3V regulators

#

2x samd21e18a in the 32-QFN package

#

Yus.

unreal pollen
#

👀

light ermine
#

You know it's turning into a serious business when you start buying in bulk.

#

And you need to start keeping track of your inventory 😄

distant raven
#

Haha yeah

elder peak
#

That's when stuff gets... reel.

carmine scarab
#

I believe you're missing the partridge in a pear tree, @distant raven! 😛

distant raven
#

@carmine scarab you’re probably right

#

I’ll include that in my next order

carmine scarab
#

"Sorry, seasonal only item"

#

So in the U.S. retail market... starting mid August I think it is now! 🤣

distant raven
#

Garcon! your finest Partridge in a pear tree!

pearl tapir
#

@distant raven Even though what I have is crappy, I couldn't live without a MRP program.

distant raven
#

MRP?

#

Sorry just got off of work and my brain is slow lol

pearl tapir
#

Manufacturing Resource Planning. It keeps up with inventory and orders with reports what you need to purchase to fill the orders.

distant raven
#

Oh yeah, I’m just starting to get into figuring out what I have total

#

I mostly just end up ordering per board type and plan for a certain number per batch.

#

But I just need to keep track of commons and only order what I need of uncommons and ICs

pearl tapir
#

The uncommons on reels or the parts that are used on multiple boards get to be a problem like connectors.

distant raven
#

Yeah

#

And buttons

fervent lance
#

i love buttons

distant raven
#

Same

#

I have only choose the most buttery of buttons

#

They cost $0.70 a piece at qty < 100

#

But they are so smooth

pearl tapir
#

If your company gets very big you will have hundreds or thousands of part numbers requiring a data base with approved vendors, alternate acceptable vendors and pricing history to control costs.

distant raven
#

Yeah, I’ve identified a few places to get these buttons from

#

Right now I get parts from Arrow Electronics and DigiKey

fervent lance
#

im new here bois im happy to start eating your knowlage

distant raven
#

Mostly Digi-Key because they tend to have what I need

pearl tapir
#

The issue will be when you have orders and Digikey is out of stock or you found it much cheaper by using octopart. Then you are going to need to keep up with who has what.

distant raven
#

Yeah, I know

#

If there’s one thing I learned in the military is logistics

#

😂

#

But yes, I’m aware of having diversified supply chains

#

My goal this year is to sell 1000 units. A modest goal

#

Maybe a little lofty

elder peak
#

So, running out of parts won't be much of a supplies for you.

pearl tapir
#

My MRP partmaster data base is 9.9MB and purchasing is 17MB. It will add up faster than you can believe.

distant raven
#

Yeah

#

I believe it

round stump
#

I'll be ordering parts (diodes, keycaps, mechanical switches, PCBs, Adafruit Itsy Bitsy M0s) for about 600 kits next month. Any advise have? I've started looking for components and I've ordered samples of all of them to make sure everything's compatible.

tough matrix
#

@round stump wow. Do you already have orders/backers for that many kits?
Have you already made final decision on which exact components you will be using?
Will you be manually assembling the PCBs, or have you contracted someone for manufacturing?

round stump
#

I think I've decided on final components for everything. Might do another part search now that I have a better idea of the final quantity I'll need to assemble.

#

Users can get kits either as a collection of components or pay $20 to have me solder them.

pale grove
#

Around how much fo CE/FCC certificates cost for a simple PCB?
Just some LEDs, resistors, capacitors, transistors etc.

No Bluetooth or anything like that

round stump
#

How many units do you plan to sell? Because FCC certification might end up costing you more than all your profits

distant raven
#

CE/FCC certification typically apply to products intended for commercial or mass consumer use.

#

If you’re producing 600 units, for instance, CE/FCC certification isn’t necessary

#

It can change when you get to the 10s of thousands or more

#

The general rule is for mass production

unreal pollen
#

Is there a specific number there? We're referencing 600 as a data point but what about 1000? Just curious what the threshold is.

round stump
#

From my own research, it's the point at which it's profitable to go after you if you don't have it.

unreal pollen
#

I've heard numbers like 15k for certification of a bluetooth board. Is that ballpark or not close?

silk lark
pearl tapir
distant raven
#

There’s no specific number

#

I was using it as an example

#

There isn’t a specific number

#

Generally you should do any board that has involuntary EMI emissions over 9kHz

#

But in most cases it really isn’t cost effective for people starting out.

#

And if you’re only selling a small handful of boards a year too. But honestly it’s best to just ask the governing boards of your board should be certified

pearl tapir
#

@distant raven If something interferes and someone complains to the FCC, it can get very expensive. Or the FCC can just say you can't build any more product. There is a significant risk if you are successful and sell a lot of boards that someone will complain.

distant raven
#

It’s true

#

I’m not saying someone should or should not. There’s just a lot to consider

pearl tapir
#

Yes. Anything that oscillates above 9kHz, as you said, is subject to FCC in the States.

distant raven
#

Yeah, for the average maker who sells a few boards, you can self certify but that comes with risks of having to produce documentation proving compliance.

#

But again always better to ask

pearl tapir
distant raven
#

Sparkfun broke it down

distant raven
#

It appears that for the most part, as long as you are not selling an end item it’s generally okay to sell. Or if your selling an item that operates in the ISM bands.

#

Though it appears that if there is potential for regulatory inquiry, you should seek out legal advice and cease sales/operation until you resolve it

#

It’s pretty gray in terms of what constitutes needing certification

pearl tapir
#

Yeah, it's kinda if you broke it, you bought it with the FCC. The only thing I've gotten certified was a 10W intentional radiator and there wasn't any question there.

elder peak
#

I think, especially at this point, there's so much whacky hardware floating around and spread-spectrum modulations are so much the default, you can probably get away with a considerable amount of unintentional radiators.

pearl tapir
#

Spread spectrum dramatically lowers the probability of interference. And a lot of that is in the ISM band. If you get interference in the ISM band, tough luck. It's your problem not an FCC issue.

distant raven
#

Yup

#

Which is probably why so many Wifi boards exist that are not FCC evaluated

#

And Bluetooth

#

And LoRa

round fog
#

Certification has been a point of irritation for me for many years. Back when I was working in a team doing a Kickstarter we agonized over it for ages. It's so hard to get decent information, that Sparkfun link is the best resource I've found and it's still super vague

#

Some people say you don't have to spend anything, some suggest that you shouldn't even try to sell things unless you can fork out 20k for a lab

#

The dev board exemption seems to be the most common thing around, but if you're trying to actually build a finished product (even an open source one) and market it as such, it's easy to get intimidated.

distant raven
#

That’s for sure. You’ll noticed some of the most prominent kickstart campaigns either are by people with friends in high places, or relatively simplistic products that fall outside the need for such certifications

brisk spire
#

Nothing special but made me happy

dark grail
brisk spire
#

Oh ya v2 will get swapped. Since I socket everything it will be high enough to be okay for most play time.

#

I only had 30 minutes to spare before cutoff and would have had to wait 2 weeks for fab

distant raven
brisk spire
#

spiffy

tough matrix
#

@round stump wow, great job!

#

i looked at the ks campaign

#

fortunately looks like most backers chose unsoldered kits, so you do not need to solder 600 kits

#

will you use digikey, mouser, lcsc?

#

lcsc might be cheaper - take a look

#

but it will also be quite a bit of work to actually repackage the components, put them in small bags, put stickers, etc...

round stump
#

I had a temp job for a year and a half when I moved to my current city of packaging componets

#

I find it enjoyable 😛

distant raven
#

Hehe

tough matrix
#

then you certainly don't need our advice 🙂

round stump
#

I think everyone here is wicked smart! I want all the collaboration I can get!

fervent lance
#

I'm making a breakout board with a bno055, a bmp388 and a h3lis331dl, I want to check if these sensors are hooked up right, before I move onto my board design

📎 unknown.png
unreal flax
#

I see you have all 3 interrupt lines tied together. Is that purposeful?

fervent lance
#

this is where I've connected the int pins, microcontroller - mk20 aka teensy 3.2

📎 unknown.png
unreal flax
#

Looks like the SA0 pin on the accelerometer is left floating. You want to tie that to ground to select I2C address 0x18.

fervent lance
#

you mean SDO

unreal flax
#

Yeah, I was just pointing out that you may want to use 3 separate interrupt lines, if you have the pins, so you can tell which chip is asserting the interrupt.

fervent lance
#

oh ok

unreal flax
fervent lance
#

I'll change that

#

any other mistakes?

unreal flax
#

Is C3 on the BNO055 CAP pin 1uF or 0.1uF? Their example in the datasheet uses the latter, but I'm not sure how much that matters.

fervent lance
#

it's 1uF

#

and I think I based it of the adafruit design

#

this is the one^

unreal flax
#

I think PIN10, PIN15, and PIN16 are supposed to be grounded instead of left floating.

#

The design you linked to shows 0.1uF.

fervent lance
#

now here's the thing - the datasheet says leave them floating, but the adafruit design says ground them

#

and I got a little confused

unreal flax
fervent lance
#

oh

unreal flax
#

Cool. Other than those issues, looks good to me. At least what I can spot in a few minutes of cross-checking. 😉

fervent lance
#

this was the only thing holding me back from ordering the board

unreal flax
#

I'm assuming you have I2C pullups on the MCU side of the schematic.

fervent lance
unreal flax
#

Some or all of the interrupt lines will probably be open-drain, so you could have pullups on those too, but it's also perfectly legit to use the GPIO pin internal pullups for that, if and when you actually use the interrupt functionality.

fervent lance
#

alright

#

time to order my boards

fervent lance
# unreal flax

I just checked the datasheet and it looks like pin 15 and 16 are left floating

unreal flax
# fervent lance

You're right. It looks like there are several different versions of the datasheet floating around. According to the revision history, it looks like the pin 15/16 recommendations were changed on 2020-02-19, with the latest from Bosch indeed being to leave them open. I see that they also updated the recommended capacitor value to the 1uF you originally had. My apologies for giving you outdated advice there...

fervent lance
#

that's perfectly ok

#

bosch datasheets are a little confusing

distant raven
#

Ah yis more boards

tough matrix
#

@fervent lance I'd suggest using lower values such as 4.7k for I2C pullups. Either value should work, but lower values usually give more reliable results - at the price of higher power consumption

fervent lance
#

sure will do that

#

I think my boss soldered on 2.2k to PCF8574 port expander SDA and SCL pins (right to the chip!)

#

I haven't seen that chip in a while; may be misremembering that value.

distant raven
#

The AT42QT1070 suggests 10k and it seems to work pretty well that way.

#

But the ADC board I assembled last night suggested 4.7k

#

Just goes to show how uncertain board design is 🙂

fervent lance
#

4.7 seems right, yeah.

#

Basically the stronger the pullup (the lower the resistor value) the faster the signal transitions state.

#

A weak pullup (higher resistor value) gives a 'mushy' signature to the edge of a pulse .. rises too slowly.

#

Transistors (totem pole) on microcontrollers operate Open Drain (or possibly, on older chips, Open Collector) on the i2c bus.

#

That means they can only sink to ground (cannot source at all).

#

The pullups provide the other side of that - they provide a means to bring those ports up to Vdd.

#

That's why nothing works without pullups on this bus.

#

Open Drain means anybody can pull the bus low (to ground) without harm.

#

So that's used in signalling (maybe in negotiating who gets to use the bus next, or who wants to use it next ;)

distant raven
#

Indeed

#

As far as I recall, i2c pull-ups should be between 2k and 10k depending on the needs/limitations of the chip and the bus.

distant raven
#

Power and no smoke

#

Just need to program it

fervent lance
#

I, too, see.

distant raven
#

Those LEDs are pretty bright for having 10k resistors eh @tough matrix

#

I was skeptical myself when Ladyada said she used 10k on her green LEDs but they really came through

elder peak
#

I guess you are now a-green with Ladyada.

distant raven
#

I wasn’t LED astray

elder peak
#

Being LED obsessed, 10k resistors are kinda against my religion. 😄

#

Oh, I found an amazing new button!

distant raven
#

Oh?

elder peak
#

Oh, yeah, so at 5 mA you would be more careful than my usual 20+ mA LEDs.

distant raven
#

Yeah, it’s rather nice

#

Power sipping goodness

elder peak
distant raven
#

Nice large through hole button

elder peak
#

Okay, so it's a 12x12 button, but it's entirely happy with perfboard and doesn't overly mind being shoved into a breadboard.

distant raven
#

Looks really nice

#

C&K is a great brand

fervent lance
#

are 10k resistors needed on the ps0 and ps1 lines on the bno055

unreal flax
#

Doesn't appear so. The example in the datasheet just ties them directly to ground or VCC.

tough matrix
#

@elder peak but $2 per button...thats half the price of RPi Pico...

vapid grove
#

By the way, did you do any rf matching, @distant raven

distant raven
#

Yeah, it uses a pi network with 1.3pF cap to a 2.9nH inductor to a 1.4pF cap.

#

I had a RF focused grad student help me design the antenna circuitry

fervent lance
elder peak
#

It compares well to going all the way to a Cherry MX switch and keycap.

unreal flax
fervent lance
#

so do I remove them or keep em

unreal flax
#

Up to you. Personally I'd follow the datasheet, since it's also easier and cheaper to not have the extra parts. If you wanted to be safest, you could use 0-ohm resistors that could could swap out for 10k if needed.

fervent lance
#

I'll follow the datasheet

fervent lance
#

does a ws2812b need a level shifting circuit

distant raven
#

No, it works 3.6V to 5.5V

fervent lance
fervent lance
supple pollen
#

Any surface mount components? Are you using copper for heatsinking?

fervent lance
#

yeah

#

I do have surface mount components

fervent lance
#

nothing too fancy

fervent lance
fervent lance
supple pollen
#

So 1 ounce copper should be fine (2 ounce is useful for heatsinking). However, for surface mount, it's often useful to spring for ENIG finishing instead of HASL, as it's flatter (it can be annoying to solder surface mount components to a less flat surface)

fervent lance
median stirrup
frigid seal
#

Ow.

#

You are paying for the rectangle. Panelize it with some smaller designs to reduce the sticker shock?

carmine scarab
distant raven
#

Want to share the back side of my SapWing board

#

Also finding out my pads for the crystal are wayyyyy to big

elder peak
#

shouldn't have padded them out so much

shy rapids
#

also nice u got the new esp32-s2

#

i want to look into them but i have many other projects going on rn

distant raven
#

Hot air solder

shy rapids
#

interesting what solder paste are u using

distant raven
#

T4

tough matrix
#

Got a business proposition about my "Logic gates" project: a guy who says he has a small startup in Zimbabwe is looking to buy 100 kits "to begin with".
Given that so far I was thinking of making maybe 50 kits, and wasn't sure if I would be able to sell them, this is looks suspicious. But then, what do I know about Zimbabwe?

distant raven
#

I know they are trying to increase the quality of stem education

tough matrix
#

as is every other nation on Earth, at least according to what they publicly declare

#

One thing I know about Zimbabwe is the reign of president Mugabe, and it doesn't inspire confidence

distant raven
#

Yeah, I’d try to at least set up video correspondence

#

Maybe open source the files so if they want to make them they can without worrying about any limbo on your end

tough matrix
#

they are already open-sourced

distant raven
#

Ah yes. 100 trillion dollars

#

Just transfer all your wealth to Zimbabwe and you’ll probably be mega rich

distant raven
#

Capacitive

#

It’s just a pad with a capacitive compatible coating on it

distant raven
#

Not really. You can make them in any shape you want

twilit mango
#

Do PCBs ever have different sized vias? Like some are larger than others? or are vias vias.

distant raven
#

@twilit mango sometimes

#

Depends on current carrying needs

twilit mango
#

Trying to design a logo and want it to at least be kind of reasonably accurate.

distant raven
#

High current power supplies can either use a lot of small via (preferred) or fewer large via (not preferred)

rain remnant
#

having soldermasks for it too?

twilit mango
#

@distant raven Ah fair enough

distant raven
#

It’s usually cheaper to use the same size via all over

twilit mango
#

I'm attempting to make a "PCB" out of my cat. Which is to say, an outline with something resembling circuits in it. Still wanted it to be potentially viable.

#

Duly noted.

#

I guess I can pretend the bigger ones are through-hole pads, and the littler ones are vias.

#

It's all rounded anyway, so not exactly a drop in replacement for an actual PCB. Also, I have no graphics skills, so we'll see if anything actually comes of this at all, or whether I end up hiring someone to do something much better.

distant raven
#

You can do bigger via if you want 🙂

#

I use 100mil via for mounting holes

supple pollen
#

Yeah, I call them "conductive elastomer buttons"

twilit mango
distant raven
#

That’s very cute looking! I love it 🙂

twilit mango
#

Thanks 😊

silk lark
#

oroboros cat

twilit mango
#

Purroborous. (I can't take credit for that one.)

supple pollen
#

I dub thee "Purrball"

median stirrup
#

how do you build a lightbox for a cat? because that lighting is excellent...

twilit mango
#

Wouldn't be the first time she's tried to get in the lightbox. Never napped in it though. But that is four Hue Ambience bulbs set to "Bright" in the general direction of the four corners of the room. And a decent mobile camera.

carmine scarab
silk lark
#

but then it becomes heavy box

carmine scarab
#

True, things like definitions do get fuzzy at that point

silk lark
#

fluffy

tough matrix
twilit mango
#

That is lovely! @tough matrix

fervent lance
#

That's on the other side of the Moon where the Chupacabra can't catch it.

rain remnant
#

almost like from kattni pcb design

tough matrix
#

yes, that's why i posted it.

#

to be honest, the drawing is not mine - I got it from some stock photo site. My only contribution was turning it into edge lit LED sign

distant raven
#

Nice

#

I built it this last Friday on my livestream 🙂

#

Much smaller

tough matrix
#

after dark looks nice

#

do you plan to make a LiPo pack for RPi Pico? I expect there is demand for it...

distant raven
#

I’ve considered it

#

It would probably be a multi-featured backpack

#

Probably battery charging, bms, some sensors, and whatnot

tough matrix
#

i think there will be demand for an inexpensive backpack that just does lipo connection and charging, nothing else

#

as long as it is $6 or lower...

distant raven
#

It would probably about $6 at my scale

#

Unless I got guaranteed interest for 100+ units

carmine scarab
#

100+, that's a lot of soldering streams! 🙂

distant raven
#

Soldering marathon 🙂

#

A 100+ commitment would be more than double what I’ve sold so far in terms of total sales

twilit mango
#

@distant raven Been there. https://www.youtube.com/watch?v=SqYOC_pNouY

YouTube
Adafruit Industries
Soldering Marathon for PyCon CircuitPython Sprints @adafruit #adafr...

This weekend we had a soldering marathon to prepare for the CircuitPython sprints at PyCon in May 2019. We soldered over 160 boards over the course of nearly 6 hours to have them available for hacking on the CircuitPython libraries at the sprints!

Visit the Adafruit shop online - http://www.adafruit.com

----------------------------------------...

▶ Play video
rain remnant
#

that is kattni been there done that

distant raven
#

That’s pretty cool @twilit mango

#

Soldering is definitely mind numbing

twilit mango
#

Thanks! I didn't want to let a good time lapse go to waste.

distant raven
#

Always worth sharing 🙂

twilit mango
#

I made my housemate do all the really annoying ones... kept subtly pushing them to his side when they came up 😆

distant raven
#

Basically I would do a marathon where I assemble as many boards as I can and test them 😂

#

My wife wouldn’t look to kindly on me having her help me

#

She’s not a techie at all

twilit mango
#

My housemate/bestie was all about it. He's far more experienced than me. I learned to solder from him.

distant raven
#

That’s really cool 🙂

twilit mango
#

He was prepared to do it again last year, then you know, conferences were cancelled. Bleh.

distant raven
#

A symbiotic housing relationship

twilit mango
#

Indeed!

distant raven
#

Those are the best

#

I think before I do a soldering marathon with SMD boards, I’m definitely getting a manual pick n place

#

Much cheaper than an $8000 pick n place

twilit mango
#

Truth.

distant raven
#

And faster than tweezers

#

Though I am pretty fast with tweezers

twilit mango
distant raven
#

Not bad at all

twilit mango
#

Thanks 😊

heavy jasper
#

My general favorite tag-teaming soldering strategy (I may have mentioned this before, apologies if I have) is to print out a larger-than-life version of the board and then have one person handle removing parts from reels and placing them on the paper where they're supposed to go on the board.

#

And then the second person handles stenciling and then is just a human pick-and-place going 1:1

#

It well-separates the higher level thinking of where components should go from the more muscle-memory operation of soldering itself, which tends to be the biggest cause of context-switch chaos when I do both myself.

#

I will often do this even if I'm alone

distant raven
#

When I did the first LiPo power pack, I stenciled 8 panels (6 on each panel) and then built 48 at once

#

🙂

#

That is a great idea though @heavy jasper

#

I think Ladyada has a tray where she separates everything out to

heavy jasper
#

I should say: most of my history comes from only having to build 3-4 boards of a thing, but each board having 100+ components

#

(from student group I was in in school)

distant raven
#

The most components I’ve put in a single board... I think 54

#

It would be pretty crazy to do 100+ components by hand

elder peak
#

My most recent three boards are the ones that finally reached the OMG SO MANY COMPONENTS point, although at least some of those are extra features that may not be on every board. I'm not sure if I should count up how many components are plausibly present or if I should live in ignorance about how much work I created for myself.

fervent lance
#

The people who never met you who hold your work in their hands abstract all that out. ;)

#

'looks like ants' they say.

#

'you don't have to go sky diving .. just look at this (hands you a lens)'

vapid grove
#

Stemma everything!

distant raven
#

I guess I could

silk lark
#

where do you people usually source those sockets?

elder peak
#

I think the genuine JST issue is in stock at Digikey.

distant raven
fervent lance
#

Anyone got any recommendation for lead-based solder, the brand I use is currently out of stock (or been for sometime) so looking at other options now.

tough matrix
fervent lance
#

@tough matrix Can't imported into the UK without high import charges.

elder peak
#

How's the Chipquik import?

fervent lance
#

Nope @elder peak

frigid seal
#

Have you checked UK based distributors like RS?

left nova
# fervent lance <@!320665963886280706> Can't imported into the UK without high import charges.

Digikey UK have that Kester spool in stock for ~£32 https://www.digikey.co.uk/products/en?keywords=24-6337-8800

24-6337-8800 Kester Solder | Soldering, Desoldering, Rework Product...

Order today, ships today. 24-6337-8800 – Leaded No-Clean Wire Solder Sn63Pb37 (63/37) 20 AWG, 22 SWG Spool, 1 lb (454 g) from Kester Solder. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

supple pollen
#

That's a good price. Then again, I'm used to the prices for 62/36/2 which is more expensive

timber sedge
#

Howdy folks. I work with HCCC, the community college in Jersey City. Last year we bought a fairly advanced robot arm (some thousands of dollars) which is currently doing jack all. It occurred to me that there was a business opportunity for short-run PCB prototypes. I clearly don't expect to compete with any of the "online" businesses, but I think because we're a) located very close to NYC and b) nonprofit (so maybe a tax write off?) we might get some business from the immediate area as far as people who don't want to wait for delivery. We can set up board printing and SMT soldering (we have plenty of room) so I think we can be pretty flexible. Do you guys think it's worth looking into?

Many thanks in advance

Joe

burnt umbra
#

Worth a look, in my opinion, yes. Keep us posted.

tough matrix
#

@timber sedge it might be

#

close to NYC is probably not all that important, as you would need to ship orders anyway, and shipping from Jersey City to Brroklyn is not much cheaper than shipping to California

#

but i know i might be interested in such a service for small runs (5-20 boards), and i am certainly not the only one

timber sedge
#

@tough matrix I mean, I would consider hand delivering myself. I would not guarantee it but I would at least consider it.

#

@tough matrix for additional reference we have a complete fabrication setup - additive, epilog laser, cnc, lathe

#

@tough matrix would you care to give some contact info to discuss further?

vapid grove
#

guys, do you know where to get LCD screens for projects?

#

I want to design a "dock" for the rpi cm4 to turn it into a tiny laptop

#

like GPD WIN

#

and I heard that it can drive a DPI display

#

fortunately, I didn't find any suppliers

silk lark
#

the usual places where you get all your other electronic parts

#

plus waveshare and good-display, maybe

vapid grove
#

I didn’t find any at LCSC

distant raven
#

Try Digi-Key

vapid grove
#

I’m out the US

#

And they don’t ship where I am

stone kindle
#

I've discovered the most annoying possible part of PCB design... fitting them into 3D designs in Fusion... x.x

stone kindle
#

figured it out

distant raven
#

Oh good

timid onyx
#

Hey - I was wondering if someone could just sanity check my layout for an XTAL - It's a 4MHz HC-49 crystal, it's a breakout for a single part so I have no need for any more density and there is an internal RC anyway so I don't even know that I'm going to end up needing the crystal

📎 unknown.png
#

The only real concern is that the traces to the right and top are analogue traces from a thermocouple - so very low voltage.

heavy jasper
#

Do the tracks to the crystal need to be as wide as they are? Could they be made thinner to also reduce capacitance (since I assume that’s why you did antipad cutouts under the chip pins)

#

You could also put down a top-layer ground ring around the crystal area, stitched to your bottom plane ground.

#

If anything I’m more worried about how close those signals are to each other

pearl tapir
#

A small cap shunting the thermocouple traces probably wouldn't affect accuracy.
Personally, I'd only connect the ground traces to the IC and not vias to below.

distant raven
#

Also, splitting ground planes can cause EMI issues

#

If you scroll back like two weeks I shared a video about it

timid onyx
heavy jasper
#

Sometimes chips will do a specific separate ground pin for crystal ground (that’s connected in the chip but not supposed to be connected externally), but doesn’t seem the case here. And yeah, I’m with veng that filtering is probably the best way to do this. Especially if you stay small enough value to use C0G/NP0 caps, which tend to be low leakage and don’t have microphonic effects.

#

Also random nit: please name more of your nets! I think 3.3V and GND are the only two meaningfully named nets on the layout

#

It’s much easier to read the layout and remember what everything does (and not have to keep looking back and forth to schematic) if signals have logical names.

timid onyx
#

Yeah you're not wrong, it's only the power rails that have names on this

heavy jasper
#

In the now, you probably have it pretty well loaded into your head, but if you need to come back to it later (or share the design with anyone) you’ll thank yourself.

unreal pollen
#

smol bois

distant raven
#

Hey nice!

unreal pollen
#

Yeah feels nice to be able to save money with smaller dev boards.

elder peak
#

A new footprint I cooked up... It's got pads for an 0805 resistor, plus two through-holes for a conventional resistor. The through-holes are sized for a pin-socket so that I can make one board with pin-sockets to try parts out and then I can make the rest of them with the resistor soldered down.

#

It's great for LED drivers and stuff where you set the current with a resistor.

cerulean crest
#

I have this project where I have two PCBs meeting at a right angle, there is a FR4 front panel, which the main PCB kinda slots into and can be soldered to. I thought this was really clever since that lets me have a NFC antenna as a part of the front panel which is visible, and all the connections for the display are easy to make, and matte black FR4 with white silkscreen and gold highlights is really quite attractive. One issue I am having is I want to have the PCB trace antenna for the bluetooth to be on the back side of the panel, so that I can raise it above other metal parts, and so its not encapsulated in the metal case, but I am having a hard time finding solutions for a right angle PCB to PCB 2.4Ghz RF connection, currently I have two PCB mount MMX connectors. Im not really happy with the current solution as its a tad expensive, was wondering if anyone else has any alternatives. I may just get off the shelf PCB trace antennas and stick them to the back of the panel and use a uFL connector

#

I also found RF contacts on digikey, but Ive never used those and am a bit unsure

distant raven
#

No way to use a flex PCB for edge connection?

#

Do a rigid flex kind of setup

heavy jasper
#

Could you just buy a separate bluetooth antenna with a ufl pigtail?

#

(which I think may be in the end what you said)

silk lark
#

bluetooth uses the same frequency as wifi, so I think you can use the same antenna?

ornate carbon
cerulean crest
cerulean crest
flat roost
#

Definitely not boring 🙂

flat vigil
#

@pale current (moving channels) what are you soldering?

pale current
flat vigil
#

I've gotten pretty far with just an iron

#

it's only the things with pads on the bottom only that are impossible to do with an iron

pale current
#

okay that makes sense, and easy enough to control if I'm just messing around making things

flat vigil
#

yup yup

#

kicad has hand solder footprints too

pale current
#

Nice, I was playing around with kicad before this, may just "copy" an adafruit design just to learn then at least I know its a good start

flat vigil
#

👍

pearl tapir
heavy jasper
#

Especially true of newer automotive parts, since it helps enable with optical inspection.

hoary zealot
#

Help me in this circut this is not giving output 🙏

polar eagle
#

okay i'm gonna take a look and see if i can figure it out but please note that i am a beginner

hoary zealot
#

Ok sir np

#

This is made in Proteus

polar eagle
#

wait so what do you want this to do

hoary zealot
#

By comparing voltage on 2 and 3 pin 1 pin gives output accordingly but there is nothing happens

#

Motor doesn't works

#

At transistor voltage shows zero

polar eagle
#

sorry i can't help with this

#

i'm really not great with PCBs

hoary zealot
#

Ohk please help me anyone who know about this ic 393n they can understand it

haughty wolf
#

what are those two wires going to the bottom of the page connected to

haughty wolf
#

why do people expect us to help with their problems if they dont give us enough information and dont stick around to answer questions?

carmine scarab
#

Remembering to provide enough information and context around any sort of problem, or even question, isn't quite a superpower, but it is a skill that does require practice, and individuals are adept at it to various levels.

proven kestrel
#

Hi, i am designing a PCB using proteus. When i create a ground plane, save and close the file, the next time i open it the ground plane dissapear ¿why is this happening?

silk lark
#

what is proteus?

proven kestrel
#

A software for PCB design

silk lark
#

that sounds like a bug in that software, perhaps you should contact their support

proven kestrel
#

I'll check, thank you.

unreal flax
#

At least in Eagle, it would only recalculate the ground-plane fills when you triggered the ratsnest command after opening a file. Possibly Proteus works the same way?

hoary zealot
hoary zealot
#

At transistor Q1 I show 0 voltage and it has to, change respectively when we gave logic state one on pin 3 and when the voltage on pin 2 is greater than pin 3 but there is nothing happens

pearl tapir
heavy jasper
#

And even then, X-ray inspection is of somewhat marginal value unless your process folks are super dialed in.... and if your process folks are super dialed in chances are the soldering itself is going well.

pearl tapir
#

My board assembler is super dialed in. MY prototype assembler (me) not so much.

median stirrup
#

Dunno if I'll bother ordering it, but I doodled up a board to go with the "NeoPIO" way of driving 8 NeoPixels from a shift register & RP2040 PIO peripheral..

unknown.png
#

need to actually verify the wire order of those JST PH LEDs..

rain remnant
#

that what you showed now to that form nice

radiant wolf
#

@median stirrup what changes did you have to make to the pio code to make it work with the shift register?

median stirrup
#

a guide will be coming up on the learn system, keep an eye out for it

radiant wolf
#

Looks interesting, thanks

#

I think I have a shift register lying around somewhere so I might give it a try

#

I am writing a neopixel library for the pico myself, mostly to get learn how to use the pio and I might try adding shift register support once I get some time

median stirrup
#

It would also be interesting to just hook 2/4/8 strips to adjacent GPIO pins

distant raven
#

ShiftyPixel would have been such a catchy name

#

NeoPIO is good too

#

Very nice board though

median stirrup
#

I couldn't decide, I got a number of good suggestions

#

and thanks -- I just want to spend more time getting confident using kicad

distant raven
#

I thought about a similar interface when I was playing around with shift registers a few months ago

#

NeoPIO would be a cool what to creat an 8 lane synchronous communication protocol

#

Imagine having a PISO coming in and doing some crazy byte frame transmissions

#

You could almost emulate Ethernet over PIO

#

Except you might need 16 total data lines

median stirrup
#

aieeee please never make me learn ethernet

distant raven
#

Well, Ethernet or not it would be cool to expland NeoPIO to create a two way interface

tough matrix
#

@distant raven: do I remember correctly that you planned to make a ESP32-S2 based board?

distant raven
#

Yeah

#

Still working on the prototype

tough matrix
#

I was looking for a board to use for controlling LED strips, for battery powered applications
so I would need LIPO connection and charger
and also a load switch to optionally diconnect the LEDs during battery charging

#

because if you have a strip of 200 NeoPixels, they use up a lot of current even when they are off

distant raven
#

Yeah, it’s true

tough matrix
#

(about 1mA per pixel, iirc)

distant raven
#

That’s actually a pretty cool application that I didn’t consider for the load switch

#

Being integrated on a MCU board for controlling high current loads

tough matrix
#

of course I can put together a sandwich of 3 boards, but it is ugly and takes space.. so I was thinking of creating a board like that based on ESP32S2 myself

#

unless someone already did that

distant raven
#

My design would probably work better on a bigger board (get it to 2 layers) and I could add some fun functionality

#

But anyway, let me know whenever you try designing it

#

I’ll make one on my side because it’s a pretty cool use case I think

median stirrup
#

this design needs mounting holes, probably bypass caps. blah.

distant raven
#

😆

stone kindle
#

does anyone have a proven Eagle library for the SK68xx series neopixels I could use?

vapid grove
#

Actually, it depends on which one you want to use

#

There are a lot of them

#

Classic 5050 one, which uses the same footprint as ws2812b

#

SK6812-MINI or -3535 comes in a smaller 3535 led footprint with 4 contacts

#

SK6812-2022 comes in 2022 led package with 4 contacts

#

There is SK6812-SIDE aka -4020 one which is a side-shining led

#

There are SK6812-2020 and SK6805-1515 which come in 2020 and 1515 packages respectively, all having contacts under the package itself, making them a terrible choice for hand-soldering and probably the only suitable soldering method is reflowing

#

So, which one you are using?

tough matrix
#

even 3535 are a pain to hand-solder - at least for me, as it is very easy to melt the plastic if you are not very careful

proper sedge
elder peak
#

I spent a bunch of time messing around with MOSFETs and MOSFET controllers so that, if I plugged in the wires backwards or accidentally put 12v on a 5v rail, it wouldn't zap my board.

#

Today, I wasn't thinking and connected the 12v power brick to the plug connected to the 5v rail and it didn't zap the board.

#

Win.

distant raven
#

Getting some RP2040 samplesssss

#

Yesss

#

Sharing for those who are making rp2040 boards

tough matrix
#

do they have a price on RP2040?
If Picos are sold for $4, I'd expect the chip itself be under $2...

distant raven
#

No price yet. Just free samples

tough matrix
#

price of $0 looks good.
Give 200 at this price, please

#

🙂

distant raven
#

😅

bright wolf
#

Hi guys, looking for some guidance on pcb design, looking to connect a pressure sensor which outputs 0-5v and convert that to 0-100 to display on a 3digit 7seg display. How difficult is it to design a custom pcb for this? I have never done anything like this.

distant raven
#

Not terribly hard

pearl tapir
#

@bright wolf Fairly easy but you don't need a custom board to test a prototype.
Adafruit has bread boards that will allow you to scale the input voltage with a couple of resistors and incorporate 12VDC to 5VDC.
https://www.adafruit.com/category/124

Breadboards & Protoboards : Adafruit Industries, Unique & fun DIY e...

Adafruit Industries, Unique & fun DIY electronics and kits : Breadboards & Protoboards - Tools Gift Certificates Arduino Cables Sensors LEDs Books Breakout Boards Power EL Wire/Tape/Panel Components & Parts LCDs & Displays Wearables Prototyping Raspberry Pi Wireless Young Engineers 3D printing NeoPixels Kits & Projects Robotics & CNC Accessories...

bright wolf
bright wolf
distant raven
#

youtube is probably the most clear way to learn

#

try out KiCAD as it's free

#

lots of community support for it

#

and plus side, is as you work on your design you can come back here and get help and some pointers on making a better design

pearl tapir
bright wolf
elder peak
#

So, I guess if @distant raven ever reaches the point where he's got too many exciting boards to make, would that make him... tapped out?

distant raven
#

well, depends.

#

😉

carmine scarab
#

At least he'd have enough not to get bored with boards. If they fall though, he may get bored by them!

distant raven
#

after I move i'm ordering some large quanitities of capacitors 🙂 in the 0402 and 0603 size. that's my commitment level 😉

carmine scarab
#

*checks the one PCB to ruler them all*
Large quanties at those sizes... so 1-2 handfuls? 😄

#

And those are to hand-solder?

distant raven
#

exactly 😉

elder peak
#

Like, I'm just making weird stuff for my own enjoyment and I'm ordering passives in strips of 100 lately.

distant raven
#

i'm going to order like... 1000 to 2000 LEDs of a single color at some point.

#

like $100-$180

elder peak
#

I collect different wavelengths.

distant raven
#

oh that is pretty nice

bright wolf
#

Hi guys, I am trying to recreate this in kicad:

ICL7107-voltmter-example.png
#

Here is what ive got so far:

unknown.png
#

its an icl 7107 in the middle with three 7 segment displays, takes in voltage and displays it on the display

#

am I going in the right direction?

#

Is there anything in the first pic I can skip putting in?

fervent lance
fervent lance
#

Looking good @bright wolf !

Two suggestions:

  • GND should always point down. I know it doesn't make a difference, but you will get used to seeing it that way.,
  • Think of using the "labelled connections" (can't remember the proper name) rather than a rat's nest of wires. Save the rats nest for the PCB.
unknown.png
royal cypress
fervent lance
distant raven
#

Lol

#

Dang, the LED I want is out of stock most everywhere at the quantity I’m looking to buy. Probably just need to back order

bright wolf
#

I barely know anything about how to use kicad so just hoping theres a simple step to test this design

fervent lance
bright wolf
#

Ill send it your way to look over once I think Im done

fervent lance
#

For actual testing. A few real PCBs take about a week to get made and shipped.

Nothing says testing like building one and finding out you've used the wrong size footprint.

distant raven
#

Or swapped power rails

#

Lol

#

These seem good. $20 cheaper at quantities that I was and low test current

#

And there is a 90K+ of them

#

Should run nicely on 130uA current too

#

The other ones I was looking at used just 30uA of power

#

With a 10k resistor

tough matrix
#

doesn't 10k resistor give 0.3mA=300uA ?

distant raven
#

.3V / 10k

#

0.00003 A

#

It’s a voltage divider, the LED will draw what it needs voltage wise. My top choice uses 3V, second choice uses 2V

#

I have a 3.3V supply, so for top choice current is set by the voltage across the resistor which is 0.3V. Current would then be 0.3V / 10000 = 30uA

tough matrix
#

oh, i see
is it really bright enough to see at this current?

distant raven
#

Yeah

#

10k on this green led

image0.jpg
frigid seal
#

Is there a cheaper & more power efficient way to sense if mains voltage is present other than a resistor and an optocoupler?

distant raven
#

Transistor

hoary spruce
distant raven
#

No, probably need a buck converter or LDO to drop it to 3.3V

pearl tapir
bright wolf
distant raven
#

My rp2040 samples will be in Monday 😄

pearl tapir
bright wolf
#

Am i correct that thats vref high?

pearl tapir
#

As I said, I didn't register.
How much does it cost to have them make a bare board?
Will they assemble some or all of the parts for you? Some quick turn houses are doing that.
I think from your description of the intended use, you didn't want a decimal point. The easiest way to do that is only load the displays for the 3 most significant digits. The IC doesn't care.
If I understand you question, there is a pot to adjust reference voltage.

fervent lance
#

I need some help with nets in EasyEDA. I am getting DRC errors and found out that it is from connecting two traces together that have different nets. Everything is correct but I need to have a way to automatically correct the net values since there is 171 DRC errors and it would take me forever to correct it manually.

tough matrix
#

@fervent lance can you share teh EasyEDA project so we can take a look?

fervent lance
bright wolf
fervent lance
#

Set all the nets to "" (no text), going to see what it does now

heavy jasper
#

@frigid seal You might be able to get away with making some non-contact AC circuit with a sensing wire next to the mains plug (ala the various electricians tools) That'd probably at least be more power efficient.

#

(this may be what skerr was getting at, but the response was a bit laconic so I figured I'd respond with a bit more detail of search terms)

distant raven
pearl tapir
#

I've had good results on a production basis using a high turns count toroid as a current sense transformer. Then a burden resistor to linearize and an op-amp.
Today, I'd just use a Hall effect sensor.
There is much charm in not connecting anything to the mains if you care about safety.

sleek marsh
#

Heya does anyone know what resistor values I should use here to get 0-24v over the LED With a 0-3v as input?

1188.jpeg
#

It's a bc107b transistor

#

Led draws 20mA btw

#

And I know I could just use a Mosfet, but I need a high switching one in that cas3

harsh pendant
#

Anyone know what I can search for, or look up to find pcb mountable version of this jst on digi key?

image0.png
unreal flax
#

If you have the part number for the inline connector, Digi-Key has a "mating part number" field in some of their listings which will usually let you find the other side of it.

harsh pendant
#

I cannot find a part number anywhere it all just says “jst”

carmine scarab
#

You can try and find some information for for it on JST's site (http://www.jst.com/). Their "Search by application, pitch or series" may be a good starting point\

tough matrix
#

but i don't think there is board mountable connector

#

you will have to use another connector such as jst ph or xh and make (crimp or solder) a wire adapter

#

<rant> I really hate when they say in description "jst connector" or "molex connector" as if there is only one type of jst/molex connector...</rant>

harsh pendant
#

Awesome thanks so much!