FW: [sdiy] Powering ICs from a Voltage Divider

[Jerry Gray-Eskue]

My thoughts on this are;

Op amp oscillation is caused by over correction of the output voltage, with
a capacitive load the time constant of the op amp cap comes into play. with
a large cap the time constant is longer and the op amp feed back delays and
slew rate are fast enough to prevent over correction. With short time
constants (small cap load) the output voltage and correction get "out of
phase" and generate the oscillation.

- Jerry

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Ian Fritz
Sent: Thursday, October 15, 2009 9:39 AM
To: simon.oo.o at xs4all.nl; synth-diy at dropmix.xs4all.nl
Subject: Re: FW: [sdiy] Powering ICs from a Voltage Divider


At 08:24 AM 10/15/2009, Simon Brouwer wrote:
>An opamp with unity gain feedback and a capacitive load is a recipe for
>instability.

True, but I have found that if the cap is really large it works OK.  Not
sure why.  Swamps out all the poles or something.

Ian

_______________________________________________
Synth-diy mailing list
Synth-diy at dropmix.xs4all.nl
http://dropmix.xs4all.nl/mailman/listinfo/synth-diy