ODP: thru zero VCO questions

[Rene Schmitz]

At 10:23 09.09.99 +0200, you wrote:
>My advise is this:
>don't look at other designs. If you have simpler idea - try it.
>As a matter of fact I wanted to do something exactly like your idea,
>but due to epidemic disease eating free time I didn't.
>What bothers me is, when the D-flop was just toggled, integrator
>voltage started to travel from max to -max, and FM input changed polarity,
>then D-flop should change again really soon.
>OK, little histeresis on window comparator would solve nose-switching
>problems, but what if it all happens really close the maximum integrator
>voltage, near the switching point? VCO will lock at opamp maximum voltage.
>OTOH such condition might appear once in a milion years during
>normal use.


Right this is a problem. Once the thresholds are exeeded, the comparators 
cannot "flip the flop" anymore. Maybe check the locking condition with a 
second pair of comparators and bruteforce discharge the cap would help.

Bye
 René
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