I'm looking for a schematic where I can set with a pot the gradual lighting and gradual going out of a LED upon hitting a SPST switch. I'm going to use this to drive a LDR. This would end up in wah. The controls are obviously for the attack and decay of wah effect.

http://members.shaw.ca/roma/wah.html

The LED in this circuit gradually goes off depending on the value of RV2. It says RV1 sets the gradual lighting of the LED. No matter I tried diferrent value of resistor and it only make the LED dimmer or brighter in all occassions, it lit immediately as I turned on the switch.

Thanks for any help.

Zener

Put a cap to ground before the resistor for the led. That should slow down the led turning off.
A coil (inductor? what are those called in english?) in series should slow down turning on, but I have no idea on how big a coil, and I've never used one. In theory that should work.

Thanks for that. I'll try that as soon as I can get a coil.

The only problem I really have with the circuit is that the LED lit IMMEDIATELY, NOT GRADUALLY no matter what the setting of the VR1.

Zener

http://www.silonex.com/audiohm/levelControl.pdf

just found this interesting link few days ago, look page 2 pic 5, maybe you could drive that circuit with some attack decay generator contructer some other way than original circuit

Maybe the original circuit works best with very slow LDRs

It's spelled LERA - the Leslie Effect Rotor Adapter at GEO.

http://www.geofex.com