Another Triangle VCO Idea

[patchell]

    Well, if this isn't a new idea, well, what can I say (I seriously
doubt there are any new ideas).

    Anyway.  So far, I have built two different triangle oscilators.
The first one used a "ota" current switch (nothing new here).  The
second one was similar to one of  Ian Fritz's oscilators that used a
pair of fet switches and a current mirror (I used JFETs).  Here is my
idea for another one:

    The exponential converter would have two identical current sinks.
One would go to the input of an opamp integrator (in the usual way), the
second will go to a current mirror.  The current mirror would be set up
to source twice the current of the exponential converter.  Also, the
current mirror would be set up so that it could be turned on and off.
    So, when the current mirror is off, the current sink would suck
current out of the integrator, making the output voltage ramp up.  When
it gets to a threshold, the current mirror would be turned on.  Since it
is sourcing twice the current as the sink, the result is that the same
amount of current is now being sourced into the integrator, as was being
sunk before.  This will cause the voltage to ramp down at the same rate.

    Don't know if I will be able to try this this weekend.  If anybody
else can follow what I said, I would be interested in the results.  Or,
is this just a bad dream?

--
 -Jim
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