Right; when the thumbswitches are toggled, the RC integrators will slow down the edges into pins 9-11. Sometimes CMOS parts will latch up or otherwise fail to reliably with slow edges -- it probably comes down to the "complementary" thing, where both halves of a totem pole can turn on erratically during a slow transition.
I have seen large capacitors used on TTL MUXes for EMI suppression, but never on CMOS. I have a feeling 100 pF would be safer and still adequate. Probably no big deal, but if you want to be anal about it, it could pay to check the edge-time specs for the HC family. -- john, KE5FX > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of David C. Partridge > Sent: Tuesday, July 15, 2008 11:07 AM > To: 'Discussion of precise time and frequency measurement' > Subject: Re: [time-nuts] Frequency divider design critique request > > > John, > > This is just DC selection of which MUX line is active. > > Am I missing something here? > > Dave > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of John Miles > Sent: 15 July 2008 18:30 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Frequency divider design critique request > > I don't know about sending edges that slow into a CMOS chip. Is that > considered kosher for HC-series logic? > > -- john, KE5FX > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] Behalf Of David C. Partridge > > Sent: Tuesday, July 15, 2008 10:16 AM > > To: 'Discussion of precise time and frequency measurement' > > Subject: Re: [time-nuts] Frequency divider design critique request > > > > > > Magnus, > > > > Was the attached what you had in mind? > > > > Thanks > > Dave > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
