Is there a way to make a tremolo from a Blinking LED?
 I have one already in the Modified EA Tremolo.
 I was thinking it would be pretty neat to have a second Tremolo on a second efkt chain, if it could be caused to go loud when the first Trem is going quiet, or on an inverted LFO wave.
 I suppose this is called a stereo auto panner...

Quote from: petemooreIs there a way to make a tremolo from a Blinking LED?
 I have one already in the Modified EA Tremolo.
 I was thinking it would be pretty neat to have a second Tremolo on a second efkt chain, if it could be caused to go loud when the first Trem is going quiet, or on an inverted LFO wave.
 I suppose this is called a stereo auto panner...

Loads of designs use LED/LDR combos.  A few were posted the other day from a French effects book (one a stereo design using LEDs).

There would probably be a delay if you used the EA's LED for a second trem, which would be a problem if that were the case.  Also, there's no way of controlling the intensity of the LED with that design, so getting the depth right would be a problem.

Easiest way would be to use a couple of FETs/trannies at the LFO's output to control a couple of LEDs and use these to control a couple of LDRs, one for each amp.  You'd have to invert the signal for one of the LEDs to do what you were suggesting.

Take a look at the Commonsound Tremulus Lune and Tremulus Panneur.

If the LED goes bright when the volume increases, you can use it to make a complementary tremolo (i.e., simultaneous volume drop on another output) by using the LED to reduce the resistance of an LDR that forms either a gain-determing part of an op-amp stage, or part of a voltage divider.

For instance, if an inverting op-amp has a 47k input resistor and a 100k feedback resistor, it will have a gain of a hair over 2.  Stick the LDR in parallel with the 100k resistor.  Since the LDR in a dark state will likely be a high enough resistance (>1meg) it won't have any effect on the parallel resistance at that point.  Once the LED comes on, the value of the LDR will drop dramatically, the total parallel resistance will plummet (e.g., 100k in parallel with 20k will give you 16.6k) and the gain of the stage will drop below unity.  You can adjust how much below unity it drops by tweaking the feedback resistor.

Bear in mind that many LDRs will have a certain amount of lag so the complementary volume drop will not be perfectly synced to the primary channel, although that might produce a more pleasing sound.

Alternatively, consider a simple passive voltage divider, made by a 47k-100k resistor and an LDR.  The LDR forms the leg-to-ground of this simulated pot.  When the LED is off,  the input-to-wiper resistance is much higher than the wiper-to-ground resistance.  When the LED goes on and the LDR resistance drops, the signal is attenuated.

Pete, here's the link for the French schematics:

http://partouze.chez.tiscali.fr/stomp/electro-moronix.htm

edit: the 'vibratos' are all tremolos.

Quote from: gezPete, here's the link for the French schematics:

http://partouze.chez.tiscali.fr/stomp/electro-moronix.htm

edit: the 'vibratos' are all tremolos.

I sure get a kick out of the commentary on that site.

MATTV: can you tell me how to turn off the LED's on the tremulus lune when the effect is off??
Mine blink all the time and I want to change it.
My lune sounds freakin amazing~!!!

Mike N.

Mike,
AFAIK, it has everything to do with how you've wired up the bypass. The usual way that Commonsound has indicated is not true-bypass, but it does turn the exterior LED off in bypass mode. They do offer the instructions for true-bypass, but as you've discovered, this leaves the exterior LED on even in bypass mode.
If you want to keep the pedal true-bypass, the easiest (and only) thing I can think of is to use a 3PDT, and use the 3rd pole for the exterior LED. For mine, I decided just to use the non true-bypass method with a DPDT.
Maybe someone else has a better idea?