Re: gEDA-user: opamp slew rate limiting

[Mark Rages <markrages@xxxxxxxxx>]

On Wed, Nov 11, 2009 at 1:14 AM, gene glick <carzrgr8@xxxxxxxxxxxxx> wrote:
> Oh, btw,
> this opamp used drives a schmitt trigger - sort of a poor mans
> comparator.  Same problem though, with the slow edge rate fooling it.
>

Now this is an interesting statement to me.  I thought the whole point
of a Schmitt input was to give the input a little "snap" and therefore
increase the rise/fall times.  In fact, I've done something similar to
what you're doing.  IIRC, it was like this: digital signal -> big long
RC -> schmitt inverter -> 4000-series flip-flop clock.   And that
circuit, inelegant as it was, worked fine.

Also, the hysteresis makes a Schmitt a questionable choice for a phase
detector if the input signal is noisy at all.

Regards,
Mark
markrages@gmail
-- 
Mark Rages, Engineer
Midwest Telecine LLC
markrages@xxxxxxxxxxxxxxxxxxx


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user