Constructed a tri-core VCO. It uses the familiar OTA - Integrator - Schmitt Trigger topology to create a +/-5v triangle and a +/-5v square that is in phase with the peaks of the triangle The tri-core works great, it can generate a stable triangle wave beyond audible range, and down to a period of tens of seconds The circuit I am using to convert the triangle to a sawtooth is shown below. The 2N7000 is a MOSFET that turns on when the gate voltage is high. This circuit is not a new design; it alternatively inverts and non-inverts the triangle wave, and mixing the square back in raises the inverted part of the traingle to match up with the non-inverted part until you get a ramp.
Except that's not what I get. I get the weird waveform below, which I show in relationship to the triangle and schmitt trigger outputs Anybody know what's wrong?
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