if you need an inverted LFO output,
to drive any LED driven effect:

just add a resistor and LED not to ground this time, but to the positive supply.

stir well, and adjust to your needs...

That's pure genius!!  So simple, I'd never have thought of it, but completely effective! Thanks!!

And here is why you would want it:
if you are trying to replace a pot in an existing circuit by voltage control,
then having two LDRs as a voltage divider, and driving them out of phase, is the go.

Or use it like Tim E. did....

yeah, quite a few compressor circuits from effects books use 'em that way

Pete

seems I got to stock up on some FX-books...  

Hi Puretube,

I tried your circuit with the envelope follower from Dr. Q(ack), the Anderton Bi Filter and the DOD Envelope follower â€" doesn’t work.
Is there something wrong or do I need a special type of envelope detector to work with?

Thanks
Bob

if this:
http://afrancesco.free.fr/fotomie/Guiteffect/quack.gif
is your circuit, it won`t work - it`s not an LED-driven effect...

sorry - couldn`t find schems for those other 2 pedals within 10 minutes...

Quote from: puretubeif this:
http://afrancesco.free.fr/fotomie/Guiteffect/quack.gif
is your circuit, it won`t work - it`s not an LED-driven effect...

yes it is... the dod is pretty similar:
http://www.harpamps.com/schematics/dodenvf.pdf
as well as the anderton circuit:
http://www.lynx.bc.ca/~jc/biFilterHammerMods.gif

what I look for is a envelope detector circuit that drives two LEDs, one inverted to the other... if you would hit the strings, one LED lights up, the other is dark and vice versa. I thought this could be done with your cct, but it isn’t that simple I think...

BoB

here:
http://www.lynx.bc.ca/~jc/biFilterHammerMods.gif
D3 prohibits the function of the LED to Ub...

http://www.harpamps.com/schematics/dodenvf.pdf
similar problem:
the LED/series resistor doesn`t "hang" at the output of an opamp directly,
but after the rectifier...

wow, you’re fast... so if I tack your circuit directly at the output of the opamp, it will work? Or am i generally wrong?

`t works with those 2opamp LFOs,
and does so at the square, as well as at the tri output;
(with the appropiate Rs, of course).