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Old 22nd Sep 2019, 7:44 am   #4
Craig Sawyers
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Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,983
Default Re: Avo valve characteristic meter

I have one with a pre-damaged meter. But I was given it for nowt, so I can't complain.

The way around a bust meter movement (open circuit) is to buy a (cheap) plastic meter of whatever sensitivity seems reasonable. Cut away the plastic (Dremel) to leave a small amount around the movement. Remove old the movement from the AVO meter, and carefully mount the new movement into the old meter case with hot melt or similar.

You can then use an op-amp circuit to have the same input resistance as the original meter, and the correct gain to mimic the sensitivity.

That way you get a meter that looks correct, and has the original scale.

Craig

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