Trouble splitting off LFO signal to drive LED
I wanted to follow up with a solution to the initial problem of splitting off an LFO signal so that I could drive it with an LED.  I never did figure out why one follower worked while the other follower didn't.  instead of using a voltage follower circuit with a 741 op amp, I used this schematic below similar to one I found in Ray Wilson's "Make" book on DIY synths.  This circuot replaces both buffers with a transistor.  From what I understand, this circuit isolates the LED control source so it doesn't affect the rest of the circuit.  Since the LFO signal is acquiescent about ground, I connected the collector and emitter to +9V and -9V respectively.  This way when the signal is low, the LED is off and when the signal is high the LED is on.







simulate this circuit &ndash; Schematic created using CircuitLab

Seems to work pretty well as an alternative to the buffer approach.  I'm still not positive that it was the solution to the LFO signal getting stuck at -5v or if I did something else inadvertently that fixed it, but this transistor approach does address a solution to the original problem of how to drive an LED from an LFO signal without drawing current from that signal.  I see this question didn't get much response, but nevertheless I didn't want to leave it hanging open once a solution to the problem surfaced.  Hope this helps someone else in the future.