VU Meter with Peak Detection

[benny_profane]

I really enjoy building utility circuits: signal routers, mixers, patch boxes, etc.—anything that can open up different options without changing fundamental elements or introducing anything new.

Even though their real utility is debatable and there are many other (better) line monitors, analogue needle VU meters have always been interesting to me. The addition of the peak detection circuit makes this more versatile and helps give a quick visual indication of transient spikes to avoid nasty clipping with my headphone amp.

I found a cheap DC meter on ebay and worked from the schematic in Figure 9 here. The SENSITIVITY control is a panel control; CALIBRATION is a trimmer. The meter didn't have a backlight, so I made a small LED daughterboard, filed out some notches, and secured it to the meter housing. It's set it so that the backlight is on when the circuit is active.

[cooder]

Super cool!
So how do you use it, with guitar signal going straight in or at end of pedal board or...?

[benny_profane]

Super cool!
So how do you use it, with guitar signal going straight in or at end of pedal board or...?

So far I've used it to get some visual feedback for different compressor settings without analyzing different recording waveforms and to normalize volume levels of different effects. I've also set it up right before my headphone amp and calibrated it so that it is set to show when I'll clip that circuit. It's a bit of a novelty, but it does have some uses. But mostly it's fun to see the needle dance and the peak indicator light up. 

[madbean]

I love it. Did you have to cut out a rectangular hole in the enclosure, or is it just affixed? Can't really tell.

[thesmokingman]

I once did a special request where they wanted to rehouse one of the joyo tech21 ripoffs but wanted a vu meter in the enclosure as well ... no real utility to it other than getting to see the needle dance

[benny_profane]

I love it. Did you have to cut out a rectangular hole in the enclosure, or is it just affixed? Can't really tell.

Thanks! Yeah I taped off the rectangle, drilled out the majority of the space, then finished it off with files. It's pretty snug in there and the jacks provide additional support. I don't want to test that by stepping on it though. The window extends 1 or 2 millimeters from the enclosure.