On Fri, Feb 22, 2013 at 10:47 AM, Hal Murray <hmur...@megapathdsl.net> wrote: >
> You can also feed the line into a modem control signal on a PC serial port. > (USB probably won't work.) The PPS logic from NTP will count cycles and > record a timestamp on the last one. Yes RS-232 wants a signal that is about +/- 9 volts. so if you are very brave all you need is a 15:1 voltage divider on the AC to scale it. However it is smarter to use a transformer. Some others who are even more conservative were using an optocoupler between the AC mains and the PC's serial port. But I think the transformer provides good enough isolation. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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. -- Chris Albertson Redondo Beach, California _______________________________________________ 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.