I'm trying to use arduino with LCD as car voltmeter. I've got R1=33kohm and R2=15kohm resistors as voltage divider. So if voltage stays below 15V from alternator it wont break arduino by going over 5V(it is the Vmax for inputs?) But i cant figure out the how to make it show voltage correctly. I've …

Arduino voltmeter calculations

heller June 1, 2011, 5:34pm 3

You mean Ref-pin? Nothing?

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