Need VU Meter Pedal

[rschultz]

Hi,

I need a VU Meter pedal to put in my chain to measure up to +5 or +8 dBu. I'd buy one if I could. Otherwise I could make one. This Welleman LED kit might work out ok.

http://www.jameco.com/1/1/51884-k4306-precision-stereo-vu-meter-2-x-15-leds-audio.html

Any ideas?

[GibsonGM]

Search the internet, you'll find a few things.  I've seen them set up with a few transistors.   The kit might be fine, but seems like more than you need (price...). 

You could build that with a few BJTs, remembering that you'll need to buffer the signal and possibly adjust your signal to match line level.  I forget where I saw it, but "DIY VU Meter" will probably get you something.  I think the site I caught one on was full of transistor projects (100 transistor projects or something like that).

Good luck! 

[karbomusic]

Hi rschultz,

I saw your PM. The one below can be calibrated to some extent IIRC. It's also buffered to keep it from affecting the guitar signal.

http://www.diystompboxes.com/smfforum/index.php?topic=110710.msg1016637#msg1016637

[PeterPan]

maybe you could startw ith this chip...

http://www.ti.com/lit/ds/symlink/lm3915.pdf

And build a simple bar graph, as in this example, or use discrete LEDs...

http://www.instructables.com/id/LED-VU-meter-that-dances-to-computer-music/

Not sure of its accuracy, but as long as its a log scale it will probely give you the comparative result you're after.

[Groovenut]

MerlinB did a thread on using the cheap battery testers on eBay as a source for the meter and a roll your own VU driver over at the other place. Merlins images are all gone now and I dont have a schematic but here's a verified layout I did. Should be easy enough to trace and redo if needed


B2 is the trimmer for the meter scaling, D2 is a 1N4148

[PRR]

> cheap battery testers on eBay

Hah! There's a bazillion of them, indeed cheap (down to $3), mostly all the same in two case types (slide and swing).

http://www.ebay.com/itm/like/181325385134?ul_noapp=true&chn=ps&lpid=82

Can NOT buy a bare meter for those prices.

(Act fast. Some are LCD digital, and I suspect this type will displace mechanical needles soon.)

In any case you need a buffer (opamp chip). Merlin's PCB shows a TL072 is ample (as would be expected). If the naked meter is 1.5V FS, then "+4dB" will bounce into the middle of the scale. The exact reading is not critical because audio is so very dynamic. Make your soundman happy, mark the meter in that range, then you can hit the same level despite gear changes.

[Jdansti]

Here's one Deadastronaut did:

http://www.diystompboxes.com/smfforum/index.php?topic=98118.msg892575#msg892575

The chip is not listed, but it's an AN6884.