Kundo 2 new Kundo clocks today

[bonusbuilt1950]

Wife and I took a 2 hour journey up to the Boston area to look at some clocks this morning. I ended up buying 2 Keinenger & Oberfell (Kundo) electro magnetic clocks. Neither one works, most don't from what I'm told. One is a square style and the other one is an oval base clock. The square one has the original battery, oval one is missing. Both take the same style battery (flat) underneath. I will convert them to AA batteries, as there's not alot of room for the C battery conversion. They are in good condition. I am happy with my purchase, as I've wanting one for a while.

 

[Robert Gift]

Wonderful clocks!
Especially like the unusual (to me) oval glass dome.

Why do they not work?
The electromagneticoil has opened somewhere?

Years ago I carefully rewound coils.

Would love to acquire such a clock and rewind the coil.
Unwind the original coil and rewind with same gauge wire and length.

 

[Schatznut]

Nice score, Robert! I've been in a Kundo electronic mode for the last few months - have acquired a number of different styles and have gotten fairly proficient at rewinding the coils. The common failure is at the joint between the lead wires and the coils - apparently Schatz used a fairly strong chemical to dissolve the coating on the magnet wire so the leads could be soldered on, and over time the residue of the chemical attacks the joints until they open up. The only solution is to strip off the old windings and rewind them. There are two basic types of motor - one that has everything enclosed in the solenoid housing and has two leads that go straight to the 1.5V source (these are the ones that seem to suffer open windings more commonly), and a newer one that has a separate circuit board under the base of the clock. Here's a copy of the patent for the early version, which contains the circuit diagram. It's tremendously elegant electronically - it works similar to a magneto ignition system in an internal combustion engine. Note it has two coils - a pickup coil and a drive coil - wound coaxially on the bobbin.

And here's what it looks like inside the solenoid housing - this one is freshly rewound and ready to be installed back in the can:

 

[Robert Gift]

And here's what it looks like inside the solenoid housing - this one is freshly rewound and ready to be installed back in the can:
View attachment 763768

Wonderful!
I do not have one. But would love to acquire one.

Wouldove to find a grocery store advertising wig-wagging device operated by a D-cell battery.
Saw them as a little boy in the late 50's or early 60's. Think thatheyvaved (that they waved) a little cardboard picture of a can of soup or something.

 

[Robert Gift]

View attachment 763768

Originally thoughthathese were totally mechanical. No transistoreplacing a mechanical switch.
If I had one, I'd be forced to replace the transistor with a Hg (mercury) switch to keep the clock free of electronicomponents.

 

[Schatznut]

Originally thoughthathese were totally mechanical. No transistoreplacing a mechanical switch.
If I had one, I'd be forced to replace the transistor with a Hg (mercury) switch to keep the clock free of electronicomponents.

I can't imagine why, or how that would work. That would be like replacing a modern electronic ignition system in a car with an old points-based distributor.

I've rebuilt a few of these and I've never seen a problem with the electronics. The operating currents and voltages are so small that there is virtually no stress on the components. And if one was found to be bad, replacement parts are readily available. Either circuit dispenses with any mechanical contacts, which seems to be the failure point on older electromagnetic drive designs. In fact, the elegance of the patented design is exactly that it uses a single active component.

A couple of things that are really cool about these clocks are that from rest, just the slightest nudge will start the motion, which gradually builds up to maximum amplitude all by itself; they draw an almost infinitesimal amount of current when in operation, and they draw no current whatsoever when the pendulum is caged.

 

[Robert Gift]

I can't imagine why, or how that would work. That would be like replacing a modern electronic ignition system in a car with an old points-based distributor.

I've rebuilt a few of these and I've never seen a problem with the electronics. The operating currents and voltages are so small that there is virtually no stress on the components. And if one was found to be bad, replacement parts are readily available. Either circuit dispenses with any mechanical contacts, which seems to be the failure point on older electromagnetic drive designs. In fact, the elegance of the patented design is exactly that it uses a single active component.

A couple of things that are really cool about these clocks are that from rest, just the slightest nudge will start the motion, which gradually builds up to maximum amplitude all by itself; they draw an almost infinitesimal amount of current when in operation, and they draw no current whatsoever when the pendulum is caged.

No problem with the solid-state switching. Well done!
Just would rather it be all mechanical, with a mercury bulb switch in place of thelectronicircuit.
(A railroad gave a glass-bottomed relay to me which causes mee-mool lights (o)T(o) to alternately flash 1 flash per second.
It is all accomplished mechanically using magnetic decay in the two coils. No electronics.)

 

[leeinv66]

I am moving this to Electric Horology as the thread has evolved past just bragging to being educational.