[sdiy-interim] Trivial OTA summing quiz!

[JH.]

B looks good, except you don't need R6.
To attenuate the output, decrease both resistors labelled with R5 by the 
same amount.
If, for some reason, you don't want to decrease R5, but need extra 
attenuation for the OTAs, R6 alone won't help. But you can connect an 
additional resistor from the left side of R6 to GND, and get attenuation by 
the current divider R6 and the extra resistor are forming.Make sure that the 
GND for this extra resistor and the GND on pin3 of the LF353 go to the same 
geometric point of your layout.

JH.

----- Original Message ----- 
From: "Paul Perry" <pfperry at melbpc.org.au>
To: <synth-diy at vermine.org>
Sent: Thursday, March 29, 2007 1:32 AM
Subject: Re: [sdiy-interim] Trivial OTA summing quiz!


My money is on C, but I'm not an EE....

best, paul perry Melbourne Australia
----- Original Message ----- 
From: "karl dalen" <dalenkarl at yahoo.se>
To: <synth-diy at vermine.org>
Sent: Thursday, March 29, 2007 9:23 AM
Subject: [sdiy-interim] Trivial OTA summing quiz!


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





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