[DonRotolo]

Just be advised that any analog (needle-type) meter can be made to display any range of voltage or current that you want.

All meter movements are essentially the same, using the D'arsonval movement. A typical meter may have a full scale sensitivity of 1 milliamp.

To convert this to a 0-5 volt voltmeter, you measure the raw voltage it takes to bring the meter to full scale. Let's say it's 1 volt (makes the math easier). You want to display 5 volts full scale. Using Ohm's law V=I*R or V/I=R, we get 1/.001=1000 Ohms of internal resistance. So we put a 4000 Ohm resistance in series with the meter, 4/5 of the voltage is dropped by the resistor, 1/5 by the meter, so a 5 volt signal puts 1 volt on the meter for a full scale reading.

To use your automotive meter, open it up, pull out the existing resistor, measure the meter, and calculate a new resistor. (Automotive meters use a second resistance to set the bottom value, 8 volts for example. Write and I'll explain it if you want)

To measure current, we do the same measurements on the meter, but now we put a smaller resistance across the meter, so most of the current goes through the shunt resistor and only a little through the meter. For example, for a 10 Amp fuss scale, we want 0.001/10 or .0001 (1/10000th) of the current to pass thru the meter, and 9999/10000th of the current to pass thru the resistor. in this case, an 0.1 Ohm resistance would make that meter read 10 Amps full scale. (A piece of 16 Ga wire serves as a decent shunt)

PM me if you don't get something, I'm short on time tonight.

Don

Just thought of somehting: A tiny servo motor would be able to display any angle using a PWM signal. Modern cars use tiny servo motors for the 'analog' gauges. Very cheap at a junkyard. Hmm, so are analog meter movements...

Don