Open source 22mm diameter PCB project


An open source 22mm diameter PCB project from Concretedog, that is available on github:

So I posted a while back about how I had used these 22mm pcb’s I’d made in prototyping an ematch ignitor system for use in rocketry. Although I made these stackable boards so they would fit inside a popular size of Estes rocket body tube I’m aware that they are quite useful for lots of things. So i’ve open sourced them so anyone can get some made, or add improve or change them.
There are three boards,an Attiny85 board with some power LED and indicator LED, a SOT89 power supply board which could be built up with either a 3.3v or a 5v supply. Finally there is a “kludge” board which is useful for adding in some thru hole components into the system. Some quick pics here but in the files on Git each board is well documented in a pdf. All the dust components are 0805 so super accessible for hand SMD soldering. :)

See the full post at Concretedog blog.

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  1. Okay I’m just too dense, but are there any technical reason(s) for the round shape? 15mm is big enough for a square board with a SMD 8-pin MCU. Easily bigger if you snip the corners. Turn it 90deg for a bigger board. What am I missing here? Hobby rockets don’t pull that many Gs right?

  2. Hey… On the blog I explain… They are primarily for going into model rockets as payload hence the form factor.

    1. Yes, obviously I have read that. Here I am just curious, I am not saying the decision is wrong or hobbyists should not do this or that. Just this: Is a round shape necessary? What are the _engineering_reasons_ for doing that? That is what I am thinking about.

      Are the PCBs round to hold the shape of a cylinder? Because if I make them more-or-less square I can easily pull wires (or even say, a moving servo cable) past the boards, compared to round PCBs with (I assume) a snug fit. So I have good reasons to keep them square-ish.

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