ohmnote

A little ohmmeter.

I wrote it in rust but it was adapted from: https://simple-circuit.com/arduino-auto-ranging-ohmmeter-lcd and https://www.hackster.io/Costalegre/auto-ranging-ohmmeter-6fa4af.

If you want to make it yourself, you can use the PCB files in the Gerbers/ directory and the 3D model in ohmnote.3mf.

BOM

• 5 4.7KΩ resistors
• 1 1MΩ resistor
• 1 100KΩ resistor
• 1 10KΩ resistor
• 1 1KΩ resistor
• 1 100Ω resistor
• 5 BJT PNP transistors (i used 2N3906 and don't know enough about transistors to be able to say what else might work)
• 2 100nf capacitors
• 1 SSD1306 OLED screen (i used this one)
• 2 Header sockets
• 1 XIAO ESP32C6 (this is what I used because I had one around, it probably wouldn't be too tough to use something else with the same form factor, you'd just have to change some code)
• Some stranded wires
• Some copper tape

Assembly

Print out the parts

Push the headers into the holes on the main part

I used my soldering iron on the lowest heat setting and they just sank in.

Push some wire through the nubbins

These will get pushed into the slots under the headers.

Secure the loose strands with copper tape

Push some other loose strands + the taped nubbins into the body

I also pushed some extra loose strands into the holes to make sure everything was conducting.

Get a PCB

I use JLCPCB personally but you do you!

Solder everything to the pcb

You can use the schematic to see what goes where.

(I didn't take a picture of this but like, you can just look at the other pictures of the board)

Connect all the wires

I crimped everything so it'd be easier to take apart if I messed something up, but you could just solder all the wires directly if you want.

Flash the code from this repo to the XIAO board

$ cargo run --release

You're done!