[time-nuts] Recording mains frequency/phase [WAS: No GPS satellites]

Charles Steinmetz csteinmetz at yandex.com
Thu Feb 26 20:39:13 EST 2015


ben wrote:

>I'm going to have to build one of these.  Assume you have some sort 
>of circuit that converts low-voltage AC from a transformer secondary 
>to a pulse train, start a timer, and count x amount of pulses?

Here is a zero-cross detector designed for this purpose:

<http://www.ko4bb.com/manuals/download.php?file=02_GPS_Timing/Simple_AC_Mains_Zero_Crossing_Detector.pdf>

Most mains-nuts feed the ZCD pulse to the DCD line of a PC's RS232 
port and use the computer to time-stamp the crossings and append them 
to a file of such time stamps.

Alternatively, Tom designed the picPET Precision Event Timer to do 
this sort of timestamping:

<http://www.leapsecond.com/pic/picpet.htm>

An Ardu/berry/bone with a flash card can also be used, so you don't 
need to leave a PC running.

Best regards,

Charles





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