Building DC Voltmeter

You are already going in the right direction. You have the range that you want but want to start at 8V. Cheap and dirty way is to insert an 8 V, zener in series with your resistance. The meter won't start to read until 8V. and the readings will be 8V. less than actual. This is not real accurate and you will lose some linearity, but for automobile use you probably won't notice.

Tom

Try Googling "expanded scale voltmeter".

for a schematic and for a text explanation of the circuit.

The 723 could be replaced by a TL431 shunt regulator or even a zener diode.

Mike

When truth is absent politics will fill the gap.

"vwq47"

** Just make the volt meter and series resistor up so it reads 10 volts DC, full scale.

Then fit 8 volt " amplified zener " in series with the lot.

This consists of an NPN transistor ( ie BC 548 ) with a small ( 400mW ) 7.5 volt zener wired from collector to base and a resistor of about 1 kohms from base to emitter.

The transistor's C-E terminals now make a sharp, low leakage 8.0 volt zener with C the anode end.

....... Phil

Thanks all - Tom , Mike and Phil . . . these are helpful suggesions. I also happened on a SC circuit of ?1995 with two 5V regulators, republished last year some time. I have lots to go on now. Thanks again - for the time and care! Dave