Stepper motor retrofit for Copal flip-clock mechanism

[dpwellis]

I got interested in the 1970s GE flip clocks a while back; I’ve now bought a total of 6 on eBay. None had working motors.

I’ve been gradually refining a stepper motor-based replacement, and it’s working pretty well. The basic stepper motors are very cheap (~$5), and the remaining electronics (microcontroller, real-time clock chip, and USB power) is also under $15. The most exotic part is the pinion gear, but I got 7 of them 3D-printed from my custom design by an on-demand service, for $30.

The mounting is very different from the original motor, of course. I just sunk a couple of machine screws into this plastic-framed flip assembly. I’ve got a second working prototype with a metal-framed mechanism (from a GE 7-4300A) but I just had to drill a couple of new holes in the frame. (It also needed a different, smaller, pinion gear).

I programmed the controller to stop the clock for an hour during “fall back” DST adjustment, and it passed its first test last weekend!

I’m putting together a blog post with all the design and details, but I couldn’t wait to share.

[Jumblejeff]

Nice! New tech meets old tech.

This might be the way to keep these old clocks working for a very long time. Most of the original gears are plastic and will some day wear out.

Cool stuff!

[flipoclock]

That is supercool, many thanks for sharing that! It will be a challenge fitting this into non-radio-flip-clocks for the housing will be much smaller, but it is a step in the right direction I suppose!

[Guest]

It would be interesting to see this retro-fitted onto the more traditional Copal movements that are made out of metal from the much earlier units (early 70s Copals). Far less space for mounting an alternative motor so another option would have to be figured out, but this is a really great step to show what can be done!

[dpwellis]

Interesting point. These clock-radios certainly afford me a lot of space to play with. However, I think there's cause for hope:

Here are some views of the retrofit sitting above a stock 7-4305F mechanism.

From the top view, you can see that the stepper is almost exactly the same depth as the original Copal.

From the back view, you can see that the motor itself has a somewhat smaller diameter, and ought to be able to fit within the profile of the Copal original, even accounting for the rectangular protrusion.

Fitting the electronics boards, and particularly the rather bulky USB power unit, might be more of a challenge, but at least they are flexible as to where they sit relative to the flip mechanism.

[gschmidt958]

Rather than using a USB power brick, I wonder if you could tap off the secondary of the transformer (if there is one) and then use an AC to DC (small) buck converter instead (or maybe a DC to DC converter along with a diode bridge package and a smoothing cap). You can find small ones on ebay. Just a thought.

Greg

[clockspot]

Well done! I have been meaning to work out something like this, having seen a similar approach here (but with an RTC, as you've done).

I'd been experimenting with replacing synchronous motors with standard quartz movements, using 3D-printed mounts and gears and a replacement movement controller to control the rate (attached are examples in a Copal 229 and Seiko DZ-701) – but they didn't have quite enough torque and ran out the battery too quickly. And I would prefer to drive the clocks in short bursts every minute, rather than continuously.

So I'm looking forward to trying the stepper motor approach, when time allows!

[flipoclock]

Great ideas! It is very cool to see some potential alternatives to our, ultimately, dying motors. As long as the coil keeps working and there is not too much play on the flywheel, we can repair everything else.

[Johnathan Terlato]

Just read through this thread as I'm considering doing something similar with a cyclometer clock with a dead motor I have, any advice?