eliminating noise from flashing led

[soundcollage]

I recently put one of those novelty rgb flashing led's in a pedal and while the effect is great it puts small clicks on the audio while it is flashing and strange synth tones while it is fading. The noise is very low and would not be a problem on stage, and the Synth tones are cool to some extent, but I would like to know if there was a way to isolate the power of the led to quiet it up for use in a studio.

[R.G.]

There's always a way. Does this unit use a series resistor? If so, split the resistor into two halves, put the LED between the two halves and parallel the LED with an electrolytic cap, maybe 47uF. This keeps the sudden change in current (which is what you are hearing) when the LED changes from being impressed on the power or ground line, as the cap acts as a local reservoir for changes and the resistors isolate it from the rest of the circuit.

[domenico]

is it the same for a 16f877 pic controlled 7 segment led display ? when led digits start flashing it make a humming noise like a tremolo pedal
this is the schematic : http://www.ucapps.de/floorboard/floorboard.pdf
thanks,
domenico

[domenico]

unfortunatelly it doesn't work with 7 segment led display, could you pleae help me ? the oscillating noise seems to come directly from the pic...if I try to put the of a gutar jack tip (the othe side is connected to my amp ) near to 16f877 I can hear a tremolo like ground noise