Re: Low distortion sinewave oscillator without big capacitor.

On Fri, 4 Apr 2025 05:14:44 +1100, Bill Sloman <bill.sloman@ieee.org>
wrote:
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On 4/04/2025 4:02 am, john larkin wrote:

On Sun, 30 Mar 2025 14:54:56 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
 

Not long ago JM posted a 1KHz sinewave oscillator with very low distortion.
It used a 470uF non polarized capacitor which in practice would probably be made from two 1000uF capacitors.
There's nothing wrong with that but I wanted to see whether I could make a working circuit without needing such a large capacitor.
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What I have so far is below.
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Any comments?

 
Suppose you built an oscillator and had a switch that varied the loop
gain between 0.98 and 1.02. Now measure the amplitude of N cycles and
flip the switch if it's too high or too low. Switch at the zero
crossing.
 
I wonder what distortion would be like.

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Why not measure it? LTSpice could probably give you a sine wave whose
amplitude ramped up linearly for a bit, and ramped back down again.
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Do a DFT on that and you'd have your answer. It wouldn't be good.
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(I wouldn't really do that. It's just an idea to play with.)

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Only if you don't know what you are talking about.

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An idea is like a cute baby puppy. Some people want to feed it and
play with it and some people want to club it to death.