• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Cheapo Ebay voltmeter

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Got a $10 0-500V LCD panel voltmeter off Ebay. Accurate enough when powered by a 9V battery, destroyed when powered with 9V that uses the same ground as the voltage being measured.
I seem to remember reading somewhere that using the same ground for the supply and the measured voltage is bad. Anybody know how to power one of these things without using a 9V battery?
Thanks,
Mike
 
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