Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Cursitor Doom Newsgroups: sci.electronics.design Subject: Re: Low distortion sinewave oscillator without big capacitor. Date: Sat, 05 Apr 2025 00:28:06 +0100 Organization: A noiseless patient Spider Lines: 55 Message-ID: References: <6640vj9335volmsgl670cqj44o3d11h7rn@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Sat, 05 Apr 2025 01:28:07 +0200 (CEST) Injection-Info: dont-email.me; posting-host="b5601b083cf70bb2e74de68af33fdac5"; logging-data="763121"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19v9mbUPjVaQjVFbKO0coTq8OHDXo8Nuc8=" User-Agent: ForteAgent/8.00.32.1272 Cancel-Lock: sha1:wcjvMKaqhg4rG2qHHO0obc9E+IM= Bytes: 3382 On Fri, 04 Apr 2025 11:32:49 -0700, john larkin wrote: >On Fri, 04 Apr 2025 18:03:19 +0100, Cursitor Doom >wrote: > >>On Thu, 03 Apr 2025 13:08:20 -0700, john larkin >>wrote: >> >>>On Fri, 4 Apr 2025 05:14:44 +1100, Bill Sloman >>>wrote: >>> >>>>On 4/04/2025 4:02 am, john larkin wrote: >>>>> On Sun, 30 Mar 2025 14:54:56 -0400, "Edward Rawde" >>>>> 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. > >Even goofy ideas sometimes evolve into great ideas, if they are not >murdered at birth. > >Electronic design, if it's not a routine mechanical activity, is about >ideas. Well, Win Hill always said it was more of an art than a science.