First timer schematic and pcb review request - Page 1
Forum section: electronics / beginners

author: Crapworks
author_rank: Newbie
timestamp: April 28, 2025, 08:56:08 am
content: Hey EEVblog community!I am very much a beginner when it comes to electronics, but since I would like to learn more about it, I recently decided to set up a small electronics lab and dive into it. The approach that works best for me when it comes to learning new things is learning by failing, so I am ready to punch my head against the wall until I understand whats happeningFor my first custom PCB I wanted to make a DIY soldering iron tip cleaner. While this is certainly not a necessity, I think it is nice to have and I hope it is easy enough for a first project. I would appreciate if you could review the schematic and the PCB layout that I came up with (and have been struggling with for multiple weeks now). A short overview over my idea:* IR LED and Phototransistor detecting the soldering iron being out into the cleaner* ATTiny is using a DRV8825 to drive a stepper motor* Break out the ATTiny pins for external programmer* All powerd by 12V DCSo all in all it whould be fairly straight forward. Please remember that I am completely new to this field and this is my first project using KiCad (or any schematics/pc editor). I would appreciate any tips and recommendations, especially when it comes to best practices when designing schematics and PCBs.I tried to keep the schematic as clean as possible and have some useful annotations. As for the PCB layout, I started from scratch about 20 times. I have no idea how people are able to route more complex board designs, but I guess this is all about experience. Thank you for taking your time to review my first electronics project!

author: xvr
author_rank: Frequent Contributor
timestamp: April 28, 2025, 10:54:28 am
content: R5 and C2 should be connected in parallel, not in seriesR1 and R3 should be placed near the pins of DRV (every extra resistance or inductance of PCB trace will spoil current sensing circuit)PCB trace between DRV and stepper should be made with maximum possible width (to carry stepper current). The same for power supply traces of DRVGround plane on bottom of PCB will be very desirablePower decoupling capacitors (C3/4/5) should be placed near pins of IC

author: Crapworks
author_rank: Newbie
timestamp: April 28, 2025, 05:41:52 pm
content: Thanks for taking your time to look at the design!Quote from: xvr on April 28, 2025, 10:54:28 amThanks for spotting this! I fixed it in the schematic and the pcb layout.Quote from: xvr on April 28, 2025, 10:54:28 amMoved them closer to the driver, thanks!Quote from: xvr on April 28, 2025, 10:54:28 amI made the traces a bit thicker, the issue is just that KiCad will not let me connect thicker traces to the IC due to the mininum clearance of the pins. Does it make sense to break out the pins and then widen the traces as soon as possible, or would that not help?Quote from: xvr on April 28, 2025, 10:54:28 amThe bottom layer is already a ground plane, I am afraid I just don't know how to properly export the pcb layers. I've attached a pdf where each layer is on a separate page, I hope this makes it more visible. If there is a consens on how to present the different layers for review, could you please point me to it?Quote from: xvr on April 28, 2025, 10:54:28 amMoved them as close to the driver as possible, thanks!

author: Benta
author_rank: Super Contributor
timestamp: April 28, 2025, 08:33:59 pm
content: I hate those "little boxes" so-called schematics. Dunno where that sick idea came from.

author: PGPG
author_rank: Frequent Contributor
timestamp: April 29, 2025, 12:06:08 am
content: Quote from: Benta on April 28, 2025, 08:33:59 pmI lost some time searching where there are second occurrences of MOSI, MISO, SCK, CLKI, ADC2, RESET labels until I gave up.

author: jwet
author_rank: Frequent Contributor
timestamp: April 29, 2025, 03:37:07 pm
content: C6 Should be 470 nF (.47 uF)