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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: The not-all-that-low distortion sine wave oscillator in a faster
 simulating version
Date: Thu, 19 Dec 2024 13:38:02 +1100
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On 19/12/2024 6:00 am, Edward Rawde wrote:
> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vjtgnp$24ubg$1@dont-email.me...
>> I've been playing with the circuit, and have got rid of one op amp, which made the simulation run much faster, but didn't help the
>> distortion performance.
>>
>> Swapping the LT1115 for the LME49710 speeded up the simulation a bit more, but didn't make any difference to the distortion
>> either. A few of the ferrite beads have gone too.
>>
> 
> I got a simulation speed of about 30us/s so I didn't wait the nearly 4 days it would take to complete.
> I did an FFT on the first few cycles and it does look 100dB down up to 1.5MHz.

It rans at 68msec/sec for me and takes a couple of minutes to run the 
full ten seconds.

> But what's the point when the circuit below is comfortably 120dB down in simulation using less than half the number of components?
> 
> It requires only a single rail and if 60dB will meet your needs then a single 9V battery is fine.
> 
> All the components are doing what I want them to do and I know what they all do.

Or think you do. You explanations haven't been all that clear.

> To attempt do any better in simulation I'd replace D1 with a precision rectifier at 0 and 180 degrees and maybe 90 and 270 too.
> 
> If building this for real then ten turn trimmers would be used for:
> R14 2.2k
> R3 68 ohm
> R16 100k
> And I'd also want R19 or part of it variable.

Why a ten turn trimmer?

Beckman ten-turn precision potentionmeters were designed to be used with 
turns-counting dials. 19mm trimmers ran around twenty turns, but weren't 
all that precisely settable.

> I wish LTSpice had a "Do you want to fix apparent line wraps Y/N". That shouldn't be hard.

First define a line wrap in terms that you can program. It's a carriage 
return and a line feed, but so is a real new line.

> Also is there any way in LTSpice to find a component?

Inspection works fine for me. Professional circuit diagrams tend to get 
re-numbered before they are released to production so the numbers run 
from left to right across the sheet in bands, then from top to bottom as 
you moved down from the top band to the bottom band.

> What I mean is let's say you have a schematic like Bill's schematic and you know that R17 is there somewhere but you don't know
> where.

It's on the non-inverting input of U7.

-- 
Bill Sloman, Sydney