[sdiy] ca3080-based tri-to-sine

[Oakley Sound]

> Right. Since the OTA is a current source,  its output current is driven 
> through the opamp feedback resistor, regardless of the value of R44.  So 
> R44 appears redundant.

I haven't seen the circuit, but I can guess we have an OTA driving an 
inverting op-amp circuit.

Yes that input resistor is redundant, but it can tell us one thing. If 
either the op-amp or the OTA dies we can tell which one is dead by 
looking at the output of the OTA and op-amp. Without that resistor you 
can't monitor the output of the OTA since its always held at GND [or 
whatever the non-inverting pin of the op-amp is sat at].

So while useless in a pure engineering front, its a useful diagnostic tool.

Tony

www.oakleysound.com