[sdiy] Outputs grounded! Re: SSI2164 datasheet updated

David G Dixon dixon at mail.ubc.ca
Mon Sep 3 09:34:04 CEST 2018

Oh yeah, you're right, there is another 4.5k resistor from the internal
connection to the control pin, making 5k.  It was late and I read the
schematic stupidly.
I'll leave them open.  I left them open on the last oscillator I built, and
nothing bad happened, and of course, they've been left open on just about
every Dixie and Rubicon in existence, and these work just fine.


From: Roman [mailto:modular at go2.pl] 
Sent: Sunday, September 02, 2018 10:44 PM
To: David G Dixon; synth-diy at synth-diy.org
Subject: Odp: Re: [sdiy] Outputs grounded! Re: SSI2164 datasheet updated

Are you saying you want to make strong POSITIVE feedback over 2164 and only
slightly dump it to GND via 5k resistor (or 10k in SSI part)? Control input
may be grounded by 500 ohm, but externally accessible is only via 2nd
resistor so 5k. Nevertheless that's nothing compared to 0 ohm positive
feedback, so it will saturate at either positive or negative depending on
offset current direction.

I think in this case it's better to leave them open than do such a thing.


Dnia 3 września 2018 07:12 David G Dixon <dixon at mail.ubc.ca> napisał(a):

Hey Team!

I am building an oscillator, and one of the 2164s has an unused VCA.  In the
layout as it is, the pins are simply unconnected.  It would require a major
layout adjustment to bring ground to these pins.

However, I then realized something: The control pin is connected internally
to ground through a 500-ohm resistor.  Hence, simply connecting all three
pins of the unused VCA together would effectively ground every pin, would it
not?  This can be done with a very simple kludge.


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