[sdiy] Davolisint Glide (T1/T2) Problem

Mike Bryant mbryant at futurehorizons.com
Sat Sep 9 10:35:54 CEST 2023


  *   I don't know whether Sziklai pairs are less stable than Darlingtons

They are actually more stable.  But as with a Darlington, they should be fed with some form of base resistor and bypass capacitor to limit frequency response.


________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Tony Allgood via Synth-diy <synth-diy at synth-diy.org>
Sent: 09 September 2023 09:31
To: synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Davolisint Glide (T1/T2) Problem

The emitter of the follower could be oscillating. Have you put an
oscilloscope on the output?

When I see circuits working without, or with extra capacitance, on the
output it usually means it's unstable. I don't know whether Sziklai
pairs are less stable than Darlingtons but that 100pF across the
base-collector on the first transistor looks to me that there could be a
stability issue that the designer has tried to tame.

Tony

www.oakleysound.com<http://www.oakleysound.com>
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________________________________
From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Tony Allgood via Synth-diy <synth-diy at synth-diy.org>
Sent: 09 September 2023 09:31
To: synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Davolisint Glide (T1/T2) Problem

The emitter of the follower could be oscillating. Have you put an
oscilloscope on the output?

When I see circuits working without, or with extra capacitance, on the
output it usually means it's unstable. I don't know whether Sziklai
pairs are less stable than Darlingtons but that 100pF across the
base-collector on the first transistor looks to me that there could be a
stability issue that the designer has tried to tame.

Tony

www.oakleysound.com<http://www.oakleysound.com>
_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy
Selling or trading? Use marketplace at synth-diy.org
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