h a l f b a k e r y
Outside the bag the box came in.
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This is a little battery powered device with a tiny linear
actuator inside, and an electronic tilt detector for
You must stick this (vertically enlarged shape) gadget to
the back of the pendulum just where their center of
mass is located.
Move the hands of the clock
to your local time (thist step
is still manual) and let the pendulum oscillate.
The tilt detector,a simple electric contact that closes
when the pendulum is as their max amplitude, will
increase an electronic counter; and the result will be
matched against an internal electronic counter driven by
a very precise quartz clock.
After a couple of hours, the difference between both
counters will be noticeable. Then the linear actuator will
move a little mass upwards if the pendulum clock is
running slow; or donwards if the pendulum clock is
After a couple of iteractions the entire center of mass of
the pendulum will be where is supposed to be, giving a
quartz precision to your old time keeping device.
Don't forget to wind the clock!
forces the wheel to oscillate in sync with the electric pulses instead of adjusting the mass, but the same basic idea. [pocmloc, Nov 24 2017]
||A lovely idea that has unfortunately already been thought of. I was trying to restore and regulate my grandfather's Eureka electric clock and I found a nice man who had made and sold exactly this device for retrofitting. Unfortunately he had stopped production and in retrospect I considered it cheating.
||I thought that this was baked, but it seems that it is not: the world-
famous clock in London's Houses of Parliament is still adjusted, to
this day, by adding and removing pennies to and from a stack on
top of the pendulum weight.
||1 penny = ~5ppm of adjustment to the tick rate. Thereby, the old
clock can be servoed to keep it in time.
||I really thought they'd changed it by now, to do exactly what you
suggest. Damn the unrealistic optimism of the telly of my youth.
||It probably shouldn't be on the pendulum. An oscillation of a quartz reference is probably not good idea.
||Or add some relativity corrections.
||On the contrary - it is highly desirable for a reference oscillator to
||Regarding Big Ben, one thing I've noticed is that the interval between the end of the chimes and the first "bong" of six o'clock varies between 10 and 15 seconds. I've never understood why this is so, since I'd assumed that the chiming and striking mechanisms were linked inexorably.
||(At the moment, the BBC is using a recording of the six o'clock chimes, while the clock is being restored, and the interval is constant at 12.5 seconds.)
||Trivia: if you are standing in Parliament Square
listening to Radio 4 FM you will hear the live bongs
from Big Ben from the radio slightly ahead of the live
bongs from the actual bell (because of the speed of
sound relative to the site of signal transmission from
the microphone next to the bells). Of course if you
are listening on DAB you'll hear the radio bongs
behind the live bongs.