[sdiy] Outputs grounded! Re: SSI2164 datasheet updated

KD KD pic24hj at gmail.com
Mon Sep 10 00:42:45 CEST 2018

2018-09-03 9:34 GMT+02:00, David G Dixon <dixon at mail.ubc.ca>:
> 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.

As per prior 2164 debate confessions and promises you made what about a golden
midway for the draconian 2164, GND output via internal 5k while
leaving input open! :-D

> 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.
> Roman

> 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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