[time-nuts] Mechanical 1PPS Oscillator Disciplining

Mark Sims holrum at hotmail.com
Sat Jan 10 17:27:37 EST 2015

Many years ago I built a GPSDPO (GPS Disciplined Pendulum Oscillator).   A friend of mine inherited a grandfather clock built in the late 1700's.   She had the movement cleaned and serviced and got the clock working fairly well,  but it was not all that accurate.  
 I built up a device using a GPS with 1PPS output,  a PIC,  an optical sensor, and a solenoid.  Basically the solenoid nudged the pendulum and kept the clock spot on.   I was expecting to have all sorts of problems figuring out where, when, and how much to nudge the pendulum,  but it pretty much worked the first time.   One major difficulty was the pendulum did not swing at 1 Hz.  I seem to remember it was 48 (or 72?) swings/minute. 		 	   		  

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