VU Meter Driver Circuit

[Yorick]

I saw these on Ebay.



They're only 35mm so it would be awesome to fit it in a pedal. So my question is: I there a simple driver circuit?

I found a lot of 2 channel drivers but they're all ready made and 2 channels.

[~arph]

They certainly look cool, a bit too deep for a stompbox perhaps? The driver circuit could just be a simple opamp boost/rectifier right? or do you want accuracy? Try the envelope follower of the nurse quacky.

[Yorick]

They're only 26mm deep so that should fit!
I'll look into those schematics and post them here, just in case someone else is interested.

[runmikeyrun]

Cool find!

I built some pedals into old Geiger counters from the 60s many years ago.  They had analog meters built in for measuring radiation.  I simply tapped off the circuit's output in parallel (AC) and rectified it through a simple bridge rectifier to get DC, thus driving the meter.  I actually had too MUCH power for the meter, so I used a trim pot to bleed off some of the current.  It works great, and I had no noticeable loss of output power or degradation of the signal from the pedal.

If for some reason your pedal didn't have enough power off your output, you could probably boost it with an LM386, that should be the simplest way to do it.

Here's a microphone I built: