circuit of the week - 2 component LFO inverter

[puretube]

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...

[lovekraft0]

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

[Paul Perry (Frostwave)]

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.

[Jason Stout]

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

[rubberlips]

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

Pete

[puretube]

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

[btraynor]

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

[puretube]

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

[puretube]

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

[btraynor]

if 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

[puretube]

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

[puretube]

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...

[btraynor]

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?

[puretube]

`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).