Has anyone tried rainbow LEDs? (not it's not a drug!)

[Geiri]

A guy requested that I put an LED that slowly changes colour so I did but it's making a noise every time it changes colour. I'm sure it has something to do with the grounding leaking through or something like that.

Here's a video of the pedal, you can clearly hear it at the end of the video: YouTube Video

So does anyone know if there's a way to eliminate the noise?

Cheers!

[Madferret]

Does the LED link back to the audio circuit by anything other than +9v and ground?

[Geiri]

Nope, literally just connected to the +9v of the DC socket and the 3PDT switch. Miro suggested putting a 9v regulator to fix it. I haven't tried it yet.

[Madferret]

Maybe try a diode on both the 9v and ground to prevent backfeed?  I'm just clutching at straws.

[Jon the Art Guy]

Off subject a bit,  but I wonder if those could be used in clipping stages,  connected to something to chage the voltage thru it?

[Geiri]

I could try it soon and see what kind of effect it has. It might be complete crap hah!

[Dave]

I had this exact problem too and would also be very interested in any potential solutions.
Thanks
Dave

[johnk]

I used one of those in my sparkle drive and it did the exact same thing (a whining sound when it changed colors) I solved it by running a resistor and a 100uf filter cap on the anode and it's now dead silent.

here's a short youtube clip of it changing color:

http://www.youtube.com/watch?v=C6nICUuv33E

[Geiri]

Mind explaining further?

[mrclean77]

Yeah, I'd like to hear more on the fix as well. I got two and never used the second b/c the one I used (in an OKF) cycles fast, then slow, then repeats, etc, etc. If you're playing...no problem, it's not audible over the chaos of the OKF, but pedal engaged and not being played:


yow---yow---yow---yow-yow-yow----yow---yow---yow


Silver lining is this particular OKF was painted by me and my (at the time) 3yo daughter, so the crazy color/noise is just kinda part of its "charm".

[johnk]

isn't it self explanatory? you just filter the dc going to the led.

[Geiri]

johnk wrote

I solved it by running a resistor and a 100uf filter cap on the anode and it's now dead silent.

Yeah, which value resistor? Just the one you use for the brightness?

[johnk]

 I had a normal value attached to the ground & cathode (like 2.2k) and from the +9V, a 100 ohm to a 100uf electrolytic to the anode.

[Geiri]

Cheers! That's what I figured but I wanted to be sure I was getting it right

[Geiri]

Why do you put the resistor on the cathode to ground? I do the opposite. I wire the cathode to the 3PDT switch and the resistor from +9v to the anode of the LED. Are you wiring it in a different way from Mark's offboard wiring layout?

[johnk]

it doesn't matter whether you put the resistor on the cathode or the anode just as long as one side has it.