Re: Low distortion sinewave oscillator without big capacitor.

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.
>
What I have so far is below.
>
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.

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.
Do a DFT on that and you'd have your answer. It wouldn't be good.

(I wouldn't really do that. It's just an idea to play with.)

Only if you don't know what you are talking about.
--
Bill Sloman, Sydney