How do you test/implement meters?
Jun 4, 2012 at 7:32 AM Thread Starter Post #1 of 4

obobskivich

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So, I've got some old meter gauges on an ancient (and tmk malfunctioning) amplifier "thing," that I want to rip off and re-purpose on a working amplifier. I don't know a thing about them, and they're probably super cheap. You can see the device here:



As it is, they feed from the live audio signal (probably through some of the transformers in there - although at 15-20V in they will actually act as output transducers :eek:), and that's fine; they overshoot and dance around like mad. That's basically what I want (yes it's just a lightshow) - so my question is, how do I take them and adapt them to take a line level signal and not the high level signal that device is designed to take right now?

I found some schematics on Elliot's site, but they assume you have a meter of known value (or a calibrated meter); I'm assuming I have neither.

Again, actual accuracy doesn't bother me here (I'm not actually after measuring VU) - just having the nifty little meters dance around to a line level signal as they do right now with a high level signal would be perfect. So how do I go about measuring/finding out more about these buggers, and implementing them?
 
Jun 4, 2012 at 8:07 AM Post #2 of 4

Avro_Arrow

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Probably the easiest way I can think of off the top of my head
is to get a couple of 5k trim pots and connect each meter
to the wiper the pot.
Connect the other ends of the pot to signal and ground.
Adjust the trim pot until you get the reading you want from the meter. 
 
Jun 4, 2012 at 12:09 PM Post #3 of 4

flecom

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usually you put an opamp to isolate it from your signal and adjust gain
 
0db should be a 1khz sinewave at 1V peak to peak IIRC
 
 

 

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