[sdiy] Adding Control Voltage

[Justin Owen]

-----Original Message-----
From: HL-SDK Synths [syntroniks at gmail.com]

>To be clear, is the signal applied to the inverting, or non-inverting input?
>Gut tells me that the diode would point towards the non-inverting, where the
> control is applied, and the non-inverting is applied.

Confirmation from some of the more experienced op-amp users would be great - but the way I do it is:

CV goes to non-inverting input
Cathode of LED goes to Inverting input
Tie the Inverting input to Ground with a resistor - base the value on what you'd normally use with an LED at whatever supply voltage you're using.
Anode of LED goes to op-amp Output

Like I said - I've only ever used this with the H11F3 (and some home made vactrols) - can't see why it wouldn't work on other commercially available optocouplers though.

Justin