ODP: thru zero VCO questions

[Martin Czech]

:::The situation is analogous to the familiar integrator-schmitt trigger
:::oscillator. Its not important in which direction the waveform starts. All
:::that is required is that at powerup the cap's voltage is within the +/-2.5V
:::window. (i.e. reset it via a switch at powerup)
:::
:::The locking you mention can occur if the waveform hits the threshold again
:::immediately after a toggle has occured. If this happens within the setup
:::time (+ propagation delay of comparator) of the FF it can lead to problems.
:::And if the FM input changes polartity within this setup time it is possible
:::that the waveform rises beyond 2.5V until the next polarity change occurs.
:::It could of course happen for a pathological FM signal that the FM input
:::doesn't bring the signal back into the window, that would be bad. I'll work
:::on that problem. 

Yes, this is the problem, arround the limits of +-2.5 noise could
lead to oscillator runaway. But this is difficult to estimate.
Practical results needed.

m.c.