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vapetrov / PCB_strain_gauge

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Update draw_footprint.ipynb #2

Closed Max-Gulda closed 5 months ago

Max-Gulda commented 5 months ago

Made the right side mirror the left side instead of going horizontal.

No idea if this was meant to be horizontal or not. Use it if you want or else disregard this commit.

vapetrov commented 5 months ago

Neat, thanks. I was lazy and made the original footprint by making it symmetric in Inkscape, so this will be useful.

Max-Gulda commented 5 months ago

Happy to help, i have some questions regarding the circuit. Of course I could print it and measure myself but maybe you can save me a couple of bucks and some time.

It's regarding the resistance of the Strain gauge. I noticed that on the schematics it says 6 ohms, is this for one strip of wires or two in series?

And do you know how much the resistance change when you bend the pcb?

vapetrov commented 5 months ago

6 ohms is the theoretical value of one of the 4 quadrants, assuming 1oz copper. The measured value was about 9 to 10Ω (there is variation from board to board), which I suspect might be due to JLC using less copper than advertised, so YMMV. When flexed all the way to 90°, there is a change of roughly 100 to 200mΩ.