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From: "Edward Rawde" <invalid@invalid.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Low distortion sinewave oscillator without big capacitor.
Date: Fri, 4 Apr 2025 22:48:13 -0400
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"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:
>>
>>> On Thu, 03 Apr 2025 13:08:20 -0700, john larkin <jl@glen--canyon.com>
>>> wrote:
>>>
>>>> On Fri, 4 Apr 2025 05:14:44 +1100, Bill Sloman <bill.sloman@ieee.org>
>>>> wrote:
>>>>
>>>>> 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.
>>>>
>>>> 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.
>>>
>>> "Please don't feed the troll."
>>
>> 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.
>
> I've got my name three patents, so I'm demonstrably capable of having ideas.
>
> I am hostile to people who tout bad ideas.

Don't you think it would be better to just explain why you think an idea is bad Bill?
And also, if necessary, to just explain how and why you think it should be done.
Being hostile doesn't make you look good and it does the opposite of persuading others that their ideas are bad.
So why be hostile at all?

>
>> Even goofy ideas sometimes evolve into great ideas, if they are not
>> murdered at birth.
>
> That's what brainstorming is about, but some ideas are hopelessly goofy.
>>
>> Electronic design, if it's not a routine mechanical activity, is about
>> ideas.
>
> Practical ideas. Ideally practicable ideas.
>
> -- 
> Bill Sloman, Sydney
>
>