Ugly but interesting

[Burkhard Rasch]

Hi Friends,found this on yesterday´s fleamarket for 2€.Case is plastic,mvmt is marked Junghans 820 .Any idea of how it works?? I can see a "wheel" or disc with an ornamental pattern like filigree.Two small "pointers" point to this without touching.When working the disc revolves with enormous speed driving a set of plastic gears and the pointers vibrate with a humming noise like a bee.Tuning fork principle??
Any comments wellcome!
Burkhard

 

[eskmill]

The magnetic escapement in these "tuning fork" movements was the invention of Englishman C.F. Clifford.

The movements in plastic housings were made in Europe by Junghans/Diehl and in Japan by Jeco.

They looked promising to the battery clock industry until cheap integrated circuits and the tiny tuning fork crystal made the magnetic escapement movements impractical.

They are an interesting phase in the development of inexpensive, reliable, low power battery clock movements with reasonable accuracy.

'Good to collect when you can find them because of the relatively short period of time when manufactured.

 

[Burkhard Rasch]

Thanks,Eckmill,I allmost was shure that You knew about those strang mvmts.Can You explain-to an idiot in electricity-how these work?I see a coil,that obviously makes a magnet on the center part of the "tuning fork" vibrate.These vibrations are transfered from the center part of the "tuningfork"to the attachment block and from there to the side parts of the fork.There I see two pointers nearly touching that "filigree"disc.But how do these make the disc revolving?And what is the geometrical pattern for?I cannot believe it´s for aesthetic reasons.I´ve never seen one like this.
Thanks for the valuable info so far!
Burkhard

 

[eskmill]

The magnetic escapement was first patented in the US by Baker, then later, Straumann. Finally in 1956, Clifford got his implementation patented.

The US Patent number is 2762222. There's a full description in English language. Hopefully, Google Patents has a German language version?

Without a doubt, the magnetic escapement was patented in other countries, England for sure.

The concept is illustrated in later editions of Britten's and De Carle's references. Maybe the same in German language clock and watch encyclopedia.

Basically, the wheel has sinusoidal teeth which follow the motion of the magnet poles. The big trick is to make it self starting and not go backward.

They "just hum along."

 

[RODALCO]

Interesting, thanks for sharing the photo's.

When I was a kid in the mid 70's I had a Diehl alarmclock with a tuning fork movement, exactly as the one described.
It made the buzzy bee sound when running and somehow the alarm buzzer was just the louder version of the buzzy bee sound.

Unfortunately it got chucked out when the 1.5 Volt C-cell battery leaked and corroded the movement in the 1980's.

It is interesting that these different designs, once popular, got superseaded by the quartz steppermotors.

 

[Wynen]

I have a "Technical Description" (sorry in German only) of the Diehl "resonic" (cal. 770, equivalent to Junghans cal. 870) on my website.
http://www.hwynen.de/resonic-770.html
The clock was developed by Diehl (see German patent no. 1.773.678, 1.901.972 and 1.922.640). By that time Junghans was a subsidiary company of Diehl.

 

[Burkhard Rasch]

Thank You verry much for the description if the movement.That was exactly what I was looking for,and even I can understand it.
Burkhard