You might be. but the rest of us don't set a date to die by. You give a whole new meaning to 'Expiration Date'! ;-)
Ahah - it uses the LT1228 as the variable-gain block. Remarkable part, I forgot that I had used it several years ago. Thanks so much for pointing that out! In a thread that started with a clipping oscillator tweaked to not get more than a few percent distortion, we evolved to the true-state-of-the-art ppb-level oscillator in a rather stellar manner.
The LT1228 of course goes way higher than audio frequencies. Gives me interesting ideas for low-distortion AGC of RF oscillators...
Tim.
IIRC it works best with about a 30mV input swing. If you have a widely varying signal, you can do something like:
---------- ! ! Vin --------/\\/\\---+--!- \\ ! ! >---+--!+\\ GND-------!+ / ! >----- ! --!-/ Iset ! !
The Iset is adjusted to always keep the input swing about the same.
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