[sdiy-interim] Trivial OTA summing quiz!

[Tim Parkhurst]

On 3/28/07, karl dalen <dalenkarl at yahoo.se> wrote:
> http://img63.imageshack.us/img63/4215/otasumdh2.jpg
>
> If one sum's lets say 5 OTA's into one op amp but need to
> dampen the amplitude into the summing OP amp wich method
> is the most adequate to use.
>
> I'm not able to reduce gain before OTA or after OP amp!
> CV are always larger in span then total OTA currents summed.
>
> Never mind the values!
>
> KD
>

Okay, I'll take a stab at it. My guess is A. This is a classic
inverting summer. You run each input through a resistor (R6) into the
inverting input of the op-amp. You can increase R6 to reduce the
signal levels coming from the OTAs, and you can change the feedback
resistor to change the overall gain (higher value reduces gain).

Any particular reason you're throwing this one at us?


Tim (stabbing in the dark) Servo
-- 
"Imagination is more important than knowledge." - Albert Einstein

_____________________________________________________________________
This is the interim list for synth-diy at dropmix.xs4all.nl.
To post, synth-diy at vermine.org
To unsubscribe, http://vermine.org/cgi-bin/mailman/listinfo/synth-diy