kundo impulse clock problem

[steve.wrigley]

Hi I have Kundo electrically impulsed pendulum clock that doesn't work. I decided to open the barrel and check the electrics. Inside I found an old transister what I think is a wire wound resister and of course the coils. One of the coils was open circuit so I rewound the coils and set it up on the bench. I'm now getting a 20ma signal from the trigger coil and 1.5v through the impulse coil gives the pendulum a good kick, but when the other components are in circuit it seems to slow it quicker than with no power to it. Does anybody have any ideas or does anybody have a spare barrel for sale. Many thanks in advance.

[steve.wrigley]

Hi I have Kundo electrically impulsed pendulum clock that doesn't work. I decided to open the barrel and check the electrics. Inside I found an old transister what I think is a wire wound resister and of course the coils. One of the coils was open circuit so I rewound the coils and set it up on the bench. I'm now getting a 20ma signal from the trigger coil and 1.5v through the impulse coil gives the pendulum a good kick, but when the other components are in circuit it seems to slow it quicker than with no power to it. Does anybody have any ideas or does anybody have a spare barrel for sale. Many thanks in advance.

[wes cobb]

he barrel assembly is available as a unit from Timesavers and probably the other clock parts wholesalers.
Wes

[Eckmill]

My own experience with the Kundo transistor clocks that have the transistor integrated into the solenoid bobbin is like yours....an open coil. I strongly suspect that the germanium transistor reaches it's end-of-life shorted causing either the drive or the feedback coil to open. The tranistor is germanium and cannot be substituted with a silicon junction device.

Those earlier and later versions have a simple one winding coil. Earliest ones used dry contact switching like the ATO and Junghans versions. The later models have an external transistor circuit. It appears to be an LC circuit approximately tuned to the 196 beats per second pendulum frequency.

More to the point of your situation in which you state that with the transistor in the circuit, the pendulum motion slows rather than being driven. From my view there's two possibilities. One, the feedback is out-of-phase with the pendulum motion retarding it rather than giving it drive. It is possible that the permanent magnet slug in the curved brass pendulum is mis-oriented. Normally the end with the red dot is outward. Of course the feedback coil leads might be reversed causing the same effect.

The other possibility is that there's a shorted turn or turns causing a severe dampening effect.

I've never understood why the brass case didn't act as a shorted turn!

Les

[Sherm]

Hi, The brass case has a slot in it which prevents it from acting as a shorted turn.

[steve.wrigley]

Thanks all. The clock's now running, Les was right about the silicon transistor not being suitable. The problem turned out to be down to the polarity of the coils and a bit of trial and error soon sorted that out. Just one poser for any electronics wizards out there, without the 6k resistor across the impulse coil the pendulum didn't have as much power and also the coils made a very quite whistleing sound in time with the pendulum swing. once again thanks for the help.