Rotating pendulum clock circuit

[Sylvia Else]

We've long had a clock somewhat similar to this

<http://www.bestpestcontrol.co.uk/ek...onal-shape-with-revolving-pendulum-1001-p.jpg>

I don't know whether that's a real torsion pendulum clock, but ours was
a pretend version, with an ordinary electronically driven clock dial,
and an entirely seperate mechanism (with a separate battery) to make the
pendulum rotate.

The other day I had a reaon to take the thing apart (one of the hands
had fallen off), and I took a look at the mechanism that drives the
pendulum. We'd long since stopped putting batteries in it, since they
seemed to run down quite quickly, and when I tried it, it no longer worked.

As far as I could see, the circuit consisted of a transisor, a resistor,
and two electrolytic capacitors. There was no mechanical connection
between the circuit and the pendulum drive. There is magnet mounted on
the drive, suggesting that the circuit produces magnetic pulses - but
there's no coil.

I eventually surmised that the required magnetic field is being
generated by a track on the circuit board. It doesn't seem very
efficient, and perhaps that's why the batteries ran down so quickly.

Anyone familiar with the technique?

Sylvia.

 

[yaputya]

We've long had a clock somewhat similar to this

<http://www.bestpestcontrol.co.uk/ek...onal-shape-with-revolving-pendulum-1001-p.jpg>

I don't know whether that's a real torsion pendulum clock, but ours was a pretend version, with an ordinary electronically driven
clock dial, and an entirely seperate mechanism (with a separate battery) to make the pendulum rotate.

The other day I had a reaon to take the thing apart (one of the hands had fallen off), and I took a look at the mechanism that
drives the pendulum. We'd long since stopped putting batteries in it, since they seemed to run down quite quickly, and when I
tried it, it no longer worked.

As far as I could see, the circuit consisted of a transisor, a resistor, and two electrolytic capacitors. There was no mechanical
connection between the circuit and the pendulum drive. There is magnet mounted on the drive, suggesting that the circuit produces
magnetic pulses - but there's no coil.

I eventually surmised that the required magnetic field is being generated by a track on the circuit board. It doesn't seem very
efficient, and perhaps that's why the batteries ran down so quickly.

Anyone familiar with the technique?

Sylvia.

Take some clear pictures of the pcb/drive and post a link.

Torsional pendulum clocks require very little power,
spring versions are called 400 day clocks - they run that
long on one winding of the spring. An interesting
variant (Atmos) runs just from variations in atmospheric
pressure.

 

[Sylvia Else]

I'd have expected an electromagnet too. I don't imagine a PCB magnet
coil would be worth SFA.

Try poking around here;
http://mb.nawcc.org/showthread.php?12874-Quartz-Anniversary-Clock-torsion-pendulum-driver

On further examination, the circuit makes no sense, there being nothing
connected to one side of one of the capacitors. I can see a small piece
of a very fine wire protruding from one of the other solder points (the
thing looks to have been hand soldered). I speculate that there was once
a fine coil there, also connected to the otherwise unconnected capacitor
terminal, that has broken off and been lost. This would explain the
failure of the mechanism years ago.

Getting the back off this thing to replace the battery is frequently a
difficult task. That coupled with what looks to have been a fragile
mechanism was clearly asking for trouble.

Sylvia.

 

[Sylvia Else]

. . .


Makes me think of various faux perpetual motion toys.

Here is a an old patent for those:

http://www.google.com.mx/patents/US5135425

The circuit is shown there but it is simpler than the one in your
clock, consisting of the battery, one transistor, the coil, and, ...
nothing else.

Andy Wood
[email protected]

A nice example of why the patent system needs a revamp.

Even the patent holder appears to have realised that the patent is
worthless, given the failure to pay the maintenance fee.

Sylvia.