A DIY Micro-Ohm Meter with Arduino (vollrathd's design & concept)

Yeah, it would not have been my preference or choice, but that’s what was available with this schematic software, LibrePCB on a mac. It took a few hours of learning the quirks of the software and I think now I like it. They do have a way to make custom symbols but I need to learn more about that, it wasn’t intuitive. There’s something about KiCad that I really don’t like, probably because it’s now mainstream. Or maybe because it does a lot of things?

Thanks, I tried to mimic the schematics I remember in Elektor Electronics magazines back when I was a teenager and I tried really hard to avoid what I didn’t like about the schematics in Electronics For You magazines of the same era. Then I watched a couple of videos about “top design mistakes in schematics” or something and did it all over again — mostly making sure all text reads left to right.

I have made a PCB before with OsmondPCB on mac, but that was without a schematic:

I’m probably making things difficult for me by using a mac. I like to work slow, I guess.

Thanks for this, I never actually needed to calculate that before — but it’s good to know now.

I followed on through to the datasheet for the 328P:

Further reading about what this could mean:

https://electronics.stackexchange.com/questions/107741/required-output-impedance-for-adc-input/107755#107755

That is true, if this was a critical reading I’d just use a INA219 since it’s a far more elegant solution. Prolonging battery life is less of a concern here, since this’ll just be used for a few seconds at a time to check connections. I did notice however that the battery voltage fell drastically after 3V —

— so this makes sense.

I’m already designing a PCB in my head for this, but I need to pace myself and not rush into it. I tend to get hyper-focussed on a single thing and forget about the rest of the world. This circuit works, so now I’ll stuff it in a food container and continue with the other projects and revisit this later and possibly make it into a product.

It has been fun though. I’ll post the code next, after I finish the comments and attributions.

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