[time-nuts] Regulating a pendulum clock (Jim Palfreyman)

[Don Mimlitch]

Jim Said:
>It also has a coil mounted near the pendulum and a fixed magnet on the
>pendulum bar and this coil connects to a box down below with a meter
>and a knob. They are labeled in sec/day. The electronics in the box
>are not clear (being quite old) but by measuring the current in the
>coil it quite simply increases the current one way to slow the clock
>and the other way to speed it up. (I'll admit the physics of this
>doesn't make sense to me - but it works!)

I have a Warren Telechron Master Clock used in Power Stations in the 20's to
regulate the 60 Cycle so that household clocks using synchronous motors would be accurate to seconds a day.

This clock has a similar permanent magnet at the end of the Pendulum and
a battery connected to a potentiometer to adjust the current flow positive or negative in an electro-magnet below the pendulum..
If the bottom of the magnet in the pendulum is "north" and the current in the electromagnet is flowing such that its top face is North, then this will repel the pendulum causing its swing to be wider and contrary to common knowledge the swing of a fixed length pendulum is not constant regardless of the swing. (Huygens discovered this in 1670 an found by forcing the arc of the swing to be cycloid instead of circular he could produce uniform oscillation) Thus if the arc is longer the swing takes more time and the clock runs slower. 
If the current flows in the opposite direction and the two magnets attract then the arc is shortened and the clock runs faster. Of course my master clock isn't as accurate as a Riefler pendulum clock. Also the magnet in my clock has lost it's magnetism over time and I can't use this regulation.

So the goal of your adaptation is to have precision control of the current flow in the positive or negative direction. Others on the list are better then me at describing how you might achieve this.