[time-nuts] Electronically Disciplined Mechanical Pendulum

Luke Mester lmester60 at gmail.com
Fri Jun 26 03:00:15 EDT 2015


Thank you for posting your project info!

One of my hobbies is collecting and repairing clocks. For several years
I've been thinking of making an add-on device to discipline pendulum
clocks. I've been using PIC based circuits to provide pendulum impulse.
I've not tried to discipline the rate as you've done.

You said that your circuit had problems locking the pendulum rate when you
used an aluminum pendulum rod. Now that you have an oak rod I was wondering
if your pendulum would remain locked when you turned off the temperature
control. With an oak rod and no temperature control your pendulum would
have temperature stability similar to common pendulum clocks. If your
circuit can maintain lock without temperature control that tells me that it
should be possible to discipline a common pendulum clock using this method.

I'm sorry, I'm asking you to perform another test on your pendulum. Can it
maintain lock with normal temperature changes? Let it run for a few days
with the heater off and see what happens.

Also, You may want to try something other than a hard drive bearing to
suspend your pendulum. Since your circuit is line powered this is not a big
problem. I've performed tests with several pendulum suspension methods
including the head support arm bearing from a hard drive. The hard drive
bearing performed poorly. You'll need less power to keep it swinging with
other suspension methods.

Using the hard drive bearing, my pendulum had a Q factor of about 2,000.
Using various traditional clock pendulum suspension springs the Q ranged
from 5,000 to 13,000. With a crossed wire suspension the Q was 28,000.

Finally, below is a link to some pictures of my clock project. I want this
to be a traditional style master clock. Something that my wife won't
complain about if I put it in the living room! I don't have the skills or
machine tools needed to build a completely mechanical master clock.
Electromagnetic impulse is my current choice.


Luke Mester

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