Quadrature VCO

[Martin Czech]

Look at J.H.'s quadrature triangle vco.
It was intended as low frequency modulator, 
optimising for tracking may be a problem.

m.c.


:::Date: Tue, 19 Sep 2000 16:33:11 -0700
:::From: patchell <patchell at silcom.com>
:::To: macdonald at evenfall.com
:::Cc: synth-diy at node12b53.a2000.nl
:::Subject: Re: Quadrature VCO
:::Content-Transfer-Encoding: 7bit
:::
:::    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
:::------------------------------------------------
:::* Visit:http://www.silcom.com/~patchell/
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:::* You didn't pay enough!
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