Re: Regulate pendulum clock with quartz crystal?

On Nov 8, 12:33 am, "jmorr...@xxxxxxxxxxx" <jmorr...@xxxxxxxxxxx>
wrote:
On Nov 7, 11:44 pm, Bill Bowden <wrongaddr...@xxxxxxx> wrote:



On Nov 6, 6:24 pm, tadchem <tadc...@xxxxxxxxxxx> wrote:

On Nov 5, 11:59 pm, Bill Bowden <wrongaddr...@xxxxxxx> wrote:

Is it possible to regulate pendulum clocks for quartz crystal accuracy
without adjusting the length of the pendulum?

Short answer: No.

Longer answer: It is not possible. The main driver for the period of
a pendulum is gravity, as first demonstrated by Galileo. Gravity
varies with the time of the solar day and the phase of the moon, as
demonstrated by the tides. We still don't know how to manipulate
gravity.

The strength of the moon's gravity is a large enough fraction of the
earth's gravity that the difference in the period of the pendulum
between having the moon at the nadir (adding to earth's gravity) and
the moon at the zenith (subtracting from earth's gravity) is easily
measured with quartz crystal clocks.

So, with a strong enough magnetic field acting on a permanent magnet
mounted to the pendulum, the force of gravity can be altered, and the
clock regulated. I was just wondering if a very brief change in
gravity at some particular position of the pendulum would change the
period?

-Bill- Hide quoted text -

- Show quoted text -

Many, many years ago their was an amateur scientisit project in
Scientific American, on this very idea.

Their solution was to fasten a small (3 cm ?) bar magnet on the back
of the pendulum shaft, nar the bob, and then readjust the pendulum so
that the clock naturally kept accurate time again.

Then they put a magnetic coil on the back of the case, so the bar
magnet would be closest to the coil when it was at bottom dead centre
of its swing. The coil was energized by a cicuit controlled by a
quartz crystal, but today, you could pull 1 Hz pulses of a GPS
satellite!

The pendulum would "lock" onto the coil pulse frequency. If the
pendulum started to get ahead, it would be retarded more than advanced
by the pulses, and vice-versa

See:
Quartz-crystal clock,
1957 Sep, pg 233
1961 Jun, pg 181
Quartz-crystal oscillator for pendulum clock,
1974 Sep, pg 192

found at

http://amasci.com/amateur/sciamdx.html#52-QQ

You betray the source of our collective wisdom, Sir!
:-)

Tom Davidson
Richmond, VA

.

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