KIENINGER & OBERGFELL Electromagnetic Clock

Robert Ryan

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Mar 16, 2019
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I have a fascination for these electromagnetic clocks. Fairly simple when they work...and almost impossible if they don't. This one works fine. The original battery was replaced. Guessing it is from the 1960s, but I don't really know....

Thanks for any comments or observations you may share.

~Bob

IMG_0629.JPG IMG_0627.JPG IMG_0624.JPG
 
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S_Owsley

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I am also fascinated with these. I have a similar one, also a K&O, but with a rectangular cover and beveled glass on the sides. I have mine running on a 1.5v AA battery. Mine runs a bit slow and I'm still trying to figure out how to get the adjustment in the middle range so that I can get it properly regulated and keep it that way. Mine loses about 5 minutes a day. There must be a service manual out there.
 

Robert Ryan

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There is available a battery adapter that holds multiple AA batteries...the advantage being longer life before changing batteries. Isn't the clock adjusted by the bell shaped weight as noted in this photo? Mine seems to be accurate for the 2 days I have had it running.
~Bob

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Schatznut

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I think the original battery holder (most of which seem to have disappeared) held multiple cells because of the battery chemistry of the day. The movement only draws about 0.3 milliwatt, so a single modern AA alkaline cell will probably start to leak long before it runs out of energy. I'm getting a clock I recently rewound into regulation and it looks like the adjuster works opposite to what I'd expect - it appears that going to the "+" side actually slows it down. It could be that the "+" and "-" signs refer to the length of the pendulum, which would make sense - making it longer would slow it down. It runs at 180bpm.

The drive for this clock is a delightfully simple magnetic repulsion motor comprised of two windings and a single germanium transistor. It works similar to an ignition system on a gasoline engine. Particularly fascinating is the ratchet-and-pawl mechanism that couples the pendulum's energy into the movement. The movement is a pretty little thing, isn't it? Mine is currently sitting in a bright spot on my workbench and it is beautiful to see when the jewels in the movement are backlit by the sun.

Here's a link to some info about these clocks - Kundo Electronique Repair. This guy is more into the electronics of the motor than the clock itself, and he disappeared down a rabbit hole on his assumption that glass-housed germanium transistors aren't available. They are - I found suitable replacements on eBay.

Here's a copy of the US patent for the original version that has everything in the solenoid housing.

Kundo patent.png
 

Robert Ryan

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I'm pleased to hear that information. I have really no knowledge of these clocks other than what I can find online. Here are a couple of photos of what I believe to be an original battery. Of course it's totally dead. Is there anyway to date these clocks? I have heard that the more recent ones contained a small circuit board.

~Bob

IMG_0630.JPG IMG_0631.JPG
 

Schatznut

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Sep 26, 2020
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I'm pleased to hear that information. I have really no knowledge of these clocks other than what I can find online. Here are a couple of photos of what I believe to be an original battery. Of course it's totally dead. Is there anyway to date these clocks? I have heard that the more recent ones contained a small circuit board.

~Bob

View attachment 638068 View attachment 638069
I've never seen one of these batteries before - very cool! And obviously dead as a brick...

The oval Kundo seems to have appeared in the late 1950's and probably was made through the mid-1960's. The latter date is my guess based on the observation that some of the 400-day clocks of this type had plastic suspension guards, which seem to have appeared in the early 1960s. The patent was applied for in 1956 and was granted in 1961, so we can assume it's no older than 1954. There was a later version that had an external circuit board - I saw one of these clear the auction block just last week.
 
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eddie268

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Jun 3, 2014
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I think the original battery holder (most of which seem to have disappeared) held multiple cells because of the battery chemistry of the day. The movement only draws about 0.3 milliwatt, so a single modern AA alkaline cell will probably start to leak long before it runs out of energy. I'm getting a clock I recently rewound into regulation and it looks like the adjuster works opposite to what I'd expect - it appears that going to the "+" side actually slows it down. It could be that the "+" and "-" signs refer to the length of the pendulum, which would make sense - making it longer would slow it down. It runs at 180bpm.

The drive for this clock is a delightfully simple magnetic repulsion motor comprised of two windings and a single germanium transistor. It works similar to an ignition system on a gasoline engine. Particularly fascinating is the ratchet-and-pawl mechanism that couples the pendulum's energy into the movement. The movement is a pretty little thing, isn't it? Mine is currently sitting in a bright spot on my workbench and it is beautiful to see when the jewels in the movement are backlit by the sun.

Here's a link to some info about these clocks - Kundo Electronique Repair. This guy is more into the electronics of the motor than the clock itself, and he disappeared down a rabbit hole on his assumption that glass-housed germanium transistors aren't available. They are - I found suitable replacements on eBay.

Here's a copy of the US patent for the original version that has everything in the solenoid housing.

View attachment 638064
Link to Full patent as above, FYI
 

Cheezhead

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Dec 30, 2010
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The OP said that he is fascinated with electromagnetic clocks so here is one I have not seen here on NAWCC or elsewhere. It is a Haller, about 8-5/8" high that I found in a Goodwill. With the rear cover removed, visible on the right is a dual? coil between the two permanent magnets held on 3 sides with the black sheet steel holder. When slowly started it is visible that the drive magnets push the pendulum in both directions. On the left is a non-magnetic (aluminum?) slug below the passing single magnet that may be what triggers the transistor to pulse the drive coil on the other end. The underside of the circuit board has 4 traces that extend along the bottom length of the board.
A metal stub on an arm operates a rachet to advance the hands.
The pendulum like other mechanical 400 day clocks is adjustable for timing accuracy and is magnetically suspended at the bottom.
This clock and my Haller GTB reveal even more that Haller was an innovative clock maker.
If someone here will explain how the transistor is triggered, please do so.
Haller1.JPG Haller2.JPG Haller3A.png
 
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