Osc reset time

[Arthur Harrison]

This idea is very interesting.  Essentially, zero-current switching of the
integrating capacitor?  Can you put up a sketch?

-Art

-----Original Message-----
From: Fraser, Colin J <Colin.Fraser at scottishpower.plc.uk>
To: 'synth-diy at mailhost.bpa.nl' <synth-diy at mailhost.bpa.nl>
Date: Wednesday, December 16, 1998 8:48 AM
Subject: Osc reset time


Thinking about using analogue switches to reset the cap in a saw wave core,
it occurs to me that it should be possible to use analogue switches so that
the capacitor does not need to be discharged to be 'reset'.

If you have a dual two-way analogue switch, with very low on resistance, you
could connect the capacitor so that you can reverse its polarity in the
circuit - ie a comparator detects the peak level and toggles the switches so
that the connections from the cap to the ref voltage and the current source
are swapped. At the next peak, they are swapped back. This should give near
instant reset times.
I would expect this has been done before if it's workable.
Is this likely to have any advantage over discharging the cap ?
Disadvantages ?


Colin f