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I recently got hold of three nice vintage flip clocks. No time keeping mechanism is present but there is something to advance the time on the clock. This mechanism has one major component labelled BT1200 Type 5. Nothing else. I can't phantom what this thing does. The component in question

The very thin wiring going in (extreme left) suggests it is not a mains component (I think).

More images can be found on [my G+ account].(https://plus.google.com/102458454375959628481/posts/Yh4YQhrHnXU)

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  • \$\begingroup\$ Trace its connections, whats it going to? That will likely provide a large insight in to what the part is. It looks like a transformer of some kind. \$\endgroup\$
    – Kris Bahnsen
    Commented May 2, 2012 at 17:26
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    \$\begingroup\$ Could be part of a synchronous AC motor, commonly used for clocks in the days before battery operated quartz time. In that case it wouldn't look like very much other than a multiturn coil of very thin wire. Is there something in the middle of the iron package that could hold a tiny little gearbox? \$\endgroup\$
    – jippie
    Commented May 2, 2012 at 17:32
  • \$\begingroup\$ The is quite a large gearbox behind it. \$\endgroup\$
    – harm
    Commented May 2, 2012 at 20:08
  • \$\begingroup\$ And it seems directly attached to mains. Which seems odd to me, but then again I have no experience with this. \$\endgroup\$
    – harm
    Commented May 2, 2012 at 20:09

2 Answers 2

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Just had a peek at your pictures. As in my comment, it looks like a synchronous AC motor. It is basically a coil of very thin wire (it doesn't have to drive a heavy load and you don't want a clock to use a lot of electricity).

The motor will step in the 50Hz rhythm of the the mains power and as long as all bearings and things are in order, the accuracy can be pretty good as long term mains frequency is very stable at 50Hz (in Europe)

It probably takes 220V, but I didn't see a type-plaatje (not sure what is called in English, but I bet you can read Dutch). I think you can rewire the clock for 110Vac with the small blue wire at the kroonsteentje but I don't think you'll want to do that.

This page shows a nice schematic presentation of how I think what's in it: Scroll down to Synchronous Motors

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  • \$\begingroup\$ So that means I can put 220V on it? And yes I know what a kroonsteentje is. I was struggling with that word too. \$\endgroup\$
    – harm
    Commented May 2, 2012 at 19:49
  • \$\begingroup\$ If it works, you may thank me, if the blue smoke escapes ... Is there nothing like a little plate that lists electrical conformity like double isolated, that sort of thing, 220Vac etc. If you're in doubt, you could put a old fashioned incandescent light bulb in series to protect it from high currents. I think the clock will take a few Watts max, so if you use a 25 or 40W bulb you should at least be safe. Measure the voltaga across, see if it starts to run (may take one or two seconds) but it will be really slow. I wouldn't expect the light bulb to light up as current will probably be very low. \$\endgroup\$
    – jippie
    Commented May 2, 2012 at 20:21
  • \$\begingroup\$ Well that worked. Sort of. I did what you suggested, put a 60W lamp in between and flipped the switch. The motor seemed to be ... vibrating. Going back and forth I guess. I read something that some of these motors needed help to start but swinging the motor in the right direction didn't help. Is there something else I can try? \$\endgroup\$
    – harm
    Commented May 3, 2012 at 19:28
  • \$\begingroup\$ Do you have a Voltmeter to test the voltage you get on the clock itself? Not sure how much, but it is supposed to make steps in a 50Hz rythm. How long did you test it for? The motor will only run very slowly. \$\endgroup\$
    – jippie
    Commented May 3, 2012 at 19:53
  • \$\begingroup\$ Strangely enough I didn't measure the voltage. Will do that somewhere this weekend. The motor was very noisy (for a motor that is) so I didn't let it run for very long (seconds). \$\endgroup\$
    – harm
    Commented May 5, 2012 at 9:39
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It's effectively an electric motor - possibly driven at mains frequency and possibly an escapement release solenoid - but maybe effectively both. Probably it provides he complete driving power for the flip action but the double lobe cam (see below) suggests triggering at regular intervals. If here is no other timing or driving mechanism then it may have been run as a "slave" with control pulses sent via the visible wiring from a central controller.

In his photo from your website you can see a general view of how it is associated with the shaft drive.

enter image description here

And here you can see the reduction gear train from the motor shaft to the flipping shaft.

enter image description here

This cam ensures an identical action every time a pulse is received.
There is a 2 lobe can face at A and A that traps the rotating cam against the lever. When a pulse is received the lever moves in direction B and he canm is free to rotate. The lever effectively travels in direction B but of course he actual motion is the shaft rotating anti0clockwise. After half a turn the shaft is again trapped against a vertical face.
If the rotating shaft is turned backwards (clockwise) it is not trapped by the cam faces. This would eg allow the drum to be turned backwards to set the time.

This mechanism may work with the same pulses used to control time clocks in older analog dial systems - used in eg British Railway Stations long ago I think - and many other such locations.

enter image description here

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  • \$\begingroup\$ Excuse my ignorance but what is a 'cam'? \$\endgroup\$
    – harm
    Commented May 3, 2012 at 7:17
  • \$\begingroup\$ @harm - The slightly snail-shell object in the last image is a cam. It is a ramp spaced out along the circumference of a shaft so that as the shaft turns different parts of the ramp are brought into contact with an "actuator". Here the actuator is the lever that is lifted from A to B by some external force releasing the cam to turn. The ramp then lowers the actuator over one 1/2 turn so that it raps the cam surface again afer one half turn. \$\endgroup\$
    – Russell McMahon ♦
    Commented May 3, 2012 at 7:56
  • \$\begingroup\$ @harm - Here are many google images of cams - most of these are camshafts from cars but cams are used in many other applications to move things in manners which are controlled by a rotating shaft. \$\endgroup\$
    – Russell McMahon ♦
    Commented May 3, 2012 at 7:56
  • \$\begingroup\$ This puts the 'lobe' also in the right perspective. :) Many thanks! \$\endgroup\$
    – harm
    Commented May 3, 2012 at 19:31

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