Use two halves of dual op amp for different purposes?

[giantsteps]

I like this LFO:

http://i210.photobucket.com/albums/bb292/frequencycentral/ClariLFO.jpg

but was wondering...since the 2nd half of the op amp is being used I assume as a unity gain buffer, could I instead take the output from the 2.2M resistor and use the other side of the op amp for perhaps a differential amplifier for another part of the circuit?

Thanks,

Chris

[Hides-His-Eyes]

You could but the loading could affect the LFO. Better to use a quad probably.

[frequencycentral]

That LFO won't drive a LED without the buffer. Unless you go direct off the opamp output, but then it's square, not triangle.

[petemoore]

  Problem might not be with quad doing some LFO and other stuff too.
  Just sayin' if I don't know, it's not bad using 2 duals instead, then it's easy to try stuff like separate the power supplies or try different low current or whatever opamp for LFO and Audio jobs.
  Perhaps a transistor buffer to free that opamp ?
  I once tied a quad into various duties, turned out it wasn't good at those...I never figured out if it could have been [some noise suggestion was made about the quad being culprit, and it seemed to be the case but I dunno...
  Just sayin' unless your prepared for retests to utilize quad, the tests may be more possible to complete if the layout can be optimized, accomodate using different types of OA's for the audio and non-audio [which tends to 'pull hard' and make 'lump' during sweep], and fiddle with the supply line[s filtering.

[PRR]

> could I instead take the output from the 2.2M resistor

There's not much signal left after 2 million ohms resistance.

And it can't be a lot less.

There's about enough to swing a TLO7x input, not enough for other uses.

[merlinb]

As a further observation: in that particular schematic the 2.2M doesn't appear to be doing anything! Relic of an older schem?

Incidentally, you can power an LED directly from the output of opamp 1, but that's no use if you'reusing it for opto modulation since its a square wave.

[jasperoosthoek]

Maybe use a darlington transistor to power the LED?

[giantsteps]

Actually the square wave output is fine...using it to trigger something else...thanks for the responses...you guys helped a lot!