Hi Simon, 1) You can use the picPET to measure zero crossings; just bias the input. 2) With no external parts at all the picPET is a 2.5V crossing detector. 3) What you find when you start playing with 60 Hz is that this is not a problem. That's why few/none of us bother with it. 4) The "time" of 60 Hz varies so much minute to minute or hour to hour that line voltage effects are mostly irrelevant. 5) The picPET input is pin5, which is a Schmitt trigger input. 6) Schmitt trigger or not, line noise is no problem for a time-stamping counter anyway.
What level of precision are you after? /tvb (i5s) > On Feb 9, 2014, at 8:04 AM, "M. Simon" <msimon6...@yahoo.com> wrote: > > Bill, > > I was hoping to avoid a device that was dependent on line voltage (rather > than zero crossings) for timing as it will then be line voltage sensitive (or > at least more than a zero crossing detector). Of course zero voltage (zero > crossing) detectors have other problems. Susceptibility to line noise being > one major one. > > Simon > > > > Engineering is the art of making what you want from what you can get at a > profit. > > > > On Sunday, February 9, 2014 3:25 PM, Bill Dailey <docdai...@gmail.com> wrote: > > The PicPET is what I use. Input is from a 5v ac transformer. Seems simple > to me. I bought a handful of these. Love em. >> >> http://www.leapsecond.com/pic/picpet.htm >> >> Doc >> >> Sent from mobile >> >> >>> On Feb 9, 2014, at 7:53 AM, "M. Simon" <msimon6...@yahoo.com> wrote: >>> >>> This probably came up during the recent discussion of Line Frequency >>> Monitoring but I may have missed it. >>> >>> >>> Does any one have a circuit (tested - operational) for monitoring line >>> frequency? I'd like something that checks zero crossing so that it is >>> relatively insensitive to line voltage variations. >>> >>> >>> Simon >>> >>> >>> Engineering is the art of making what you want from what you can get at a >>> profit. >>> _______________________________________________ >>> 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. _______________________________________________ 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.
