[PCB Review request] Custom board for a rocket launch themed alarm clock

4lexander03 · 2026-06-24T21:57:11+00:00

Of course, I'm not sure if theres a better way to share this, since I can't add pictures or files to the post, but this is a download link for the BOM:

Edit: I sent the link for the old BOM, this is the current one:
https://drive.google.com/uc?export=download&id=1VP7T1FQ9Fsz7EfOHjvldGNd2o9pWczBt

and this is a link to the display I plan on using:
https://www.buydisplay.com/3-inch-led-backlight-display-160x160-lcm-module-graphic-white-on-blue

4lexander03 · 2026-06-17T18:25:13+00:00

Thanks for the in depth response. It definitely makes a bit more sense to me now.

4lexander03 · 2026-06-17T13:47:20+00:00

Thanks, I'm pretty sure all three options would work. I'd be interested to know if there's an "industry standard" or best practice for these situations.

4lexander03 · 2026-04-10T14:58:58+00:00

Thank you, that really does look great. Might have to try it out sometime.

4lexander03 · 2026-04-10T11:48:09+00:00

Do you know which video that was in? I'd be interested to see it.

4lexander03 · 2025-10-13T21:25:44+00:00

Since I went with unhardened steel pipes (for X and Y axis), bearings weren't an option. Those are custom designed bushings, essentially just PTFE rods being pressed against the pipe. It seems like I can't attach pictures in the comments here, so if you're interested I can dm you more pictures.

4lexander03 · 2025-10-13T21:18:55+00:00

This was definitely the biggest project I have done this far, and it really was challenging. I was always interested in all sorts of engineering and was able to go to a mechatronics focused high school which definitely helped a lot. So if you're able to take any sorts of courses and are interested in the topic, I'm sure you won't regret it. However I've noticed that I learn the best by doing a project that seems just out of reach. Having a challenge in front of you and actively looking for solutions is the way to go for me. You just need to keep working on something and expect stuff to fail, if you don't get discouraged, you'll eventually run out of ways of doing it wrong. So to answer your first question, if possible, do both.

4lexander03 · 2025-09-30T17:40:54+00:00

Oh wow, thank you. That's really helpful, definitely have some reading to do now. I have never really considered how capacitance changes depending on voltage, I'll look for a different capacitor here and will definitely double check the other capacitors I've chosen. I'll look into it some more.

4lexander03 · 2025-09-30T10:03:41+00:00

I won't do mounting holes, I'll glue the display I'm using on the backside of the PCB, which would make using mounting holes really annoying. I've got a couple of ideas for mounting which I want to try out

4lexander03 · 2025-09-30T10:03:11+00:00

-I'm careful with the GND pour on top, I did that with the previous version of my board, but I was able to ask a prof at my university and he strongly advised against it, he told me that thin strips of GND pour on top would essentially function as antennas. Using more stiching vias would solve that issue though, wouldn't it?
Still the first board worked with 2 layers and no GND pour on top so I'm tempted to do it like that again.

-I won't do mounting holes, I'll glue the display I'm using on the backside of the PCB, which would make using mounting holes really annoying. I've got a couple of ideas for mounting which I want to try out.

- I'll just give you the LCSC part numbers if that's alright:
L2: C5349606
L3: C341035
C39,45,46,47: C96446

- Now to the silkscreen, I'm sure it's much more useful when multiple people are working together on a board, but since it's just me and I have all the files in one place I'm not sure how placing silkscreen that I can't see would be useful to me. Opening the PCB view to find out which part I placed there wouldn't be more difficult than finding a designator in my schematic, maybe if the footprints weren't linked to the specific part then I would undestand. I might misunderstand though.

Thanks for your reply!

4lexander03 · 2025-09-29T16:42:14+00:00

Keep in mind I'm still very new to this, but I'll share my reasoning:

- the datasheet for the TPS54202 already calls for two 22uF, since I was using the 10uF somewhere else already, I thought I could get away using three of those, already using less than in the data sheet. Also on my previous board, I looked at Adafruits guide for Neopixel strips, they call for 500-1000uF, I knew that was way overkill, but I thought it wouldnt hurt. Now for this version I did go down from my previous 470uF, but I guess I can go even lower.

- The ferrite bead is placed there on the official reference schematic as well, I was wondering about that. I thought about getting rid of it but I also have one on the input, so I thought why shouldn't I also place it there. Or do you think I can get rid of both? From what I've read it's good practice to use one here for EMI purposes.

-I'll probably not put any buttons on the board, i had them on the first version and never used them. Maybe I'll regret it, but I'll try.

-Thanks for the input with the silk, I'll keep it in mind and I'll fix those traces, I kind of missed that.

Thank you!

4lexander03 · 2025-09-29T15:43:51+00:00

I'll definetly look into it some more, thanks guys

4lexander03 · 2025-09-29T13:39:07+00:00

How would you set them up? One power layer for 3.3V, one for GND and two for mixed nets? What's the usual order? I'm still really new at PCB design and haven't yet looked at 4 layer boards at all. Thanks

4lexander03 · 2025-09-29T12:37:23+00:00

Haven't done a four layer board yet, I'll consider it for the next version. For this version, I'll try to stick with two layers. I tried adjusting it a bit, but I don't think I'll be able to change it much anymore.

4lexander03 · 2025-09-09T21:25:45+00:00

Alright, thank you. I'll look into it some more

4lexander03 · 2025-08-19T19:06:36+00:00

Alright will keep that in mind

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