Re: Low distortion sinewave oscillator without big capacitor.

On 5/04/2025 1:48 pm, Edward Rawde wrote:

"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vsq3um$107nb$1@dont-email.me...

On 5/04/2025 5:32 am, john larkin wrote:

On Fri, 04 Apr 2025 18:03:19 +0100, Cursitor Doom <cd@notformail.com>
wrote:
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On Thu, 03 Apr 2025 13:08:20 -0700, john larkin <jl@glen--canyon.com>
wrote:
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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?

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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.
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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.

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"Please don't feed the troll."

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The point here is that some people, especially fatheads with advanced
degrees, are incapable of having ideas, and react by being hostile to
ideas and to people who have them.

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I've got my name three patents, so I'm demonstrably capable of having ideas.
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I am hostile to people who tout bad ideas.

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Don't you think it would be better to just explain why you think an idea is bad Bill?

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I usually do.
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And also, if necessary, to just explain how and why you think it should be done.

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I have been known to do that. You should know - I've done it to you, here, and I'm about to do it to John May whom I really like
and approve of.
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Being hostile doesn't make you look good and it does the opposite of persuading others that their ideas are bad.

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Few people can ever be persuaded that their ideas are bad. John Larkin definitely isn't one of them.
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So why be hostile at all?

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The same mechanism that persuades people that their bad ideas aren't too bad allows them to gloss over any criticism that isn't
thoroughly explicit.

>
>
--
Bill Sloman, Sydney