Add an LED to this build?

[markr04]

Please forgive a n00b. Can I add an LED to this build? I tried replacing one of the 914 diodes with an LED, but it didn't light up - still had the same sound though.

I built another auto filter that had LEDs in it. One of them pulsed as the circuit did its filter thing. Is it possible here?

Here's a link to the Tonepad .pdf:
http://www.tonepad.com/getFile.asp?id=5

Thanks so much for your time and knowledge!
Mark

[travissk]

The diode has a drop of about 0.6V (for silicon junctions). Past that it will "turn on," and the more voltage you put across it, the brighter it will get... until it pops. That's why you use a current-limiting resistor in series. So the easy answer is to put more voltage/current through it

The problem is, the diodes in that circuit look to serve a functional rather than visual purpose, and getting enough juice through them to light up your pedalboard will negatively impact your circuit... it probably won't work with too big a drop. That said, there are probably places where you can add in a little circuit to shoot off light to the beat of the envelope detector.

What was the other filter you built? That diode might have been specially added to pulse with the funk, or it could be adapted to work here.