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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: AF Osc AGC alternatives to lamp/thermistor/FET
Date: Sun, 20 Oct 2024 08:38:15 -0700
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On Sun, 20 Oct 2024 14:15:19 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>Yesterday in the thread "Random thoughts on sinewave oscillators" I 
>posted a LT Spice wirelist showing amplitude levelling without fet, ntc 
>thermistor or ptc filament instead using current steering long tail pair 
>- kinda poor mans multiplier.
>
>Here is another alternative, using diode conductance bridge "variolosser".
>
>For the full 1960s vibe replace U2 U3 with bjt current sources.

That's still limiting a Wein bridge, essentially a single-element
resonator.

If you do the double-integrator type oscillator, you can do gain
control on the first integrator, and then the second one adds 6
dB/octave harmonic reduction.

I think you can even get 12 dB/octave harmonic reduction if you do the
amplitude limiter right. 12*3 = 36!