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Signal amp for vu meter- help! Answered

I am creating a VU meter with my arduino board soon. I would like the vu meter to output the same amount of light even if the input audio is lower or giher (if i change the volume, I dont want the vu meters range to fluctuate). Does anyone know of a device that will maintain a constant signal voltage regardless of whether the inout signal is high or low?
I'm not fussed if this amplifying circuit distorts the signal a bit as I am not actually using it to listen to afterwards.


Do you just want flashing lights then?


It sounds more like you want a threshold detector rather than a VU circuit.

I can see three possible interpretations here.

One is that you really do want a VU meter, in which case Steve is essentially correct -- it's very specifically defined. See the references pointed to by http://en.wikipedia.org/wiki/VU_meter.

Another would that you want a general indication of relative signal level. In that case, you might want to be able to adjust the range being covered, in which case having an adjustable preamplifier might be desirable. Or, since you're talking about doing this in software, you could just tell the program to scale the values.

Another would be that you just want pretty lights. In that case, you might want an "automatic gain control" so it dynamically scaled itself over some reasonable time period and within some reasonable constraints. Again, since you're talking about building this around an Arduino, I'd suggest doing that in software.

... Or, of course, you may be trying to do something completely different, in which case you definitely want to clarify your question.

Isn't having a constant input defeating the point of the VU meter, which is to monitor input levels ?