Quadrature VCO

[patchell]

    Yes it is.  In the Nov/.Dec 1980 issue of Polyphony there is a circuit
that uses a single CA3280, but an LM13700 could be used instead.  Another
reference, if you don't have that one is page 80 in the Analog Devices
Non-linear circuits handbook (which is where the first circuit I mentioned
was derived).  If you don't have either, I can xerox off a copy and send
them to you.

Chris MacDonald wrote:

> Is it possible to build a QVCO around a single LM13700?  I have tried to
> make one by starting with a 2nd order state variable filter but was
> unable to achieve strong, stable oscillation without clipping on at
> least one of the waveforms.  Did I miss something here?  Is there an
> otherwise "standard" or "classic" circuit for a QVCO?  I don't need
> through-zero or anything, just nice sine waves up to 25kHz or so.
>
> Thanks,
>
> Chris MacDonald

--
 -Jim
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