ODP: thru zero VCO questions

[Cal Grant]

On Fri, 10 Sep 1999, Roman Sowa wrote:

> Maybe a second set of comparators (window comparator) with
> higher thresholds (by, say, 0.1V), so if the first set fails to toggle
> the FF and integrator goes beyond first threshold, the second set
> forces FF toggle. This only minimizes the risk of lockup. Not so good.
> BTW VCO is locked up until FM input changes polarity again.
> 
> OR
> now I get Harry's idea of pulse spray. A clock oscillator (100Hz?)
> fed into AND gate, the other AND gate input goes to window comparator
> output. When integrator output exceedes valid range (copmarators
> thresholds) the AND gate issues next pulse. AND may be ORed with
> comparators output for normal operation.

Guys,

>From my personal experience with electronics, the above 'fixes' sound like
"BandAids" of sorts. These kinds of "if we just add this..." things
rarely work out well.  I think that a re-thinking of the concept is in
order, so as to more clearly define the requirements and the overall
function of the circuit.

I don't have anything to add or suggest for this circuit myself, just the
above advice, from many (too many?) years of analog electronic design.

take care,

cj

"... the side effects of cruising at the speed of life..."