Re: Building DC Voltmeter

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


"Phil Allison" <philallison@xxxxxxxxxx> wrote in message
news:5gvskvF3ic8chU1@xxxxxxxxxxxxxxxxxxxxx

"vwq47"

I'm wanting to built a DC volmeter from a moving coil ammeter. I have
all the info and can calculate the series resitstor I need to make a
(say) 1-20V meter. It's an automotive use. What I would like to do do
is offset the zero so the zero reading is say 8V and the maximum 18V. I
can't for the life of me find a simple circuit that will work, though I
knowq I have seen them, using a regulator. Can anyone point me in the
right direction please?



** 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







.

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