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From: "Edward Rawde" <invalid@invalid.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Final final 1kHz oscillator
Date: Sun, 10 Nov 2024 00:49:36 -0500
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"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgnkgg$3p31a$1@dont-email.me...
> On 9/11/2024 7:39 pm, Edward Rawde wrote:
>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:vgn4gm$3lcor$1@dont-email.me...
>>> On 9/11/2024 7:43 am, Edward Rawde wrote:
>>>> This is the simplest circuit I can come up with.
>>>> Harmonics are more than 80dB down in simulation.
>>>> FFT the last 30 seconds.
>>>> There is only one harmonic stopping me claiming 90dB but the exact FFT result can depend
>>>> on exactly how much output is selected for the FFT. You may see different results.
>>>>

I have fixed my circuit but it raises more questions than it answers.
This circuit deliberately has no text and no u symbols so should be ready to simulate.
If you let it complete (about 20 minutes on a fast PC) the FFT should show at least 80dB purity and there aren't many harmonics 
standing in the way of 90dB.
Startup isn't fast and it takes at least 20 seconds of simulation to fully settle.

There are two things I don't understand about my own circuit.

1. Why does LT1678 work fine in position U2 but LT1057 does not.
2. Why is the DC stabilization circuit (U3 and associated components) needed and would it work just the same in reality?

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