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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: Final final 1kHz oscillator
Date: Tue, 19 Nov 2024 23:46:34 +1100
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On 18/11/2024 2:58 pm, Edward Rawde wrote:
> "JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:n7iijjdeqecl0kmub0bq5in0dbm60m7qam@4ax.com...
>> On Thu, 14 Nov 2024 11:14:28 -0500, "Edward Rawde"
>> <invalid@invalid.invalid> wrote:
>>
>>> "JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:t5fajjdteskfftvkf84iqsp2vc4b9ta5kj@4ax.com...
>>>> On Fri, 8 Nov 2024 15:43:41 -0500, "Edward Rawde"
>>>> <invalid@invalid.invalid> wrote:

Here's another variation. This one take's John May's advice and spreads 
the phase shift oscillator over three op amps, all operating with the 
non-inverting input grounded.

U1 now has only one 3.3pF frequency compensation capacitor - the 
simulation started slowing down to picoseconds per second from time to 
time, and this made it happen less often. The two compensation capacitor 
scheme would probably be fine in real life.

The circuit takes a long time to settle down to stable operation - about 
5 seconds,and that after I cut the integrating capacitor from 6.8uF to 
680nF and put in D4 to minimise the initial overshoot on the FET gate 
drive - and the performance isn't wonderful. The second and third 
harmonics are about 75dB below the fundamental and 65dB down 
respectively. I'll play about a bit more but the main charm of the 
circuit is that it is easy to explain what each bit does.

Version 4
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