); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Hi Grant:
Your re-triggerable monostable idea has been implemented and is called a "missing pulse detector". Have Fun, Brooke Clarke http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam Grant Hodgson wrote: > ); SAEximRunCond expanded to false > Errors-To: [EMAIL PROTECTED] RETRY > > I'm working on a synth. project which can take either an external 10MHz > reference input or use an internal TCXO. It would be nice if the > presence (or more importantly, failure) of the external 10MHz ref. could > be detected automatically, and signaled to the user. > > There are, of course, a number of ways to do this. One is to use a > level detecting circuit; simply AM detect the ext. ref. input and apply > to a comparator. Lots of circuits to do this, no problem - but requires > a number of components, unless there is some magic IC that will do it > that I'm not aware of - I suppose a dual op-amp is all that's needed, > plus a handful of discretes. > > Another option might be to use a re-triggerable monostable, which is > constantly looking for the presence of (say) a falling edge every 100nS > on the ext. ref. input line. It would seem that conceptually, this > would be the easiest way, possibly using less components. Does anybody > have any favourite circuits for this; or are there any caveats that are > not mentioned in the plethora of monostable circuits that are mentioned > on the 'web? > > Mnay (older) test equipments have an int/ext switch on the back, with an > indicator on the front, but some newer ones detect the ext. ref. and > switch automatically. I suppose that's not a problem on a $$$$ box, > which this synth. is not. > > The output would simply be a high/low digital line, the ext. ref. input > will of course be buffered; I can cope with switching the 10MHz signals. > > Any ideas appreciated. > > regards > > Grant > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.