Retro Flip Clock Gets A Retrofit

Retro tech is almost always ripe for the hacking — be it nostalgia, an educational teardown, or acknowledging and preserving the shoulders upon which we stand. Coming across an old West-German built flip clock, YouTuber [Aaron Christophel] retrofitted the device while retaining its original mechanical components!

No modern electronics are complete without LEDs of some kind, so he has included a strip in the base of the clock face for visibility and cool factor. He doesn’t speak to the state of the clock beforehand, but he was able to keep the moving bits of the clock working for its second shot at life.

Controlling the clock is an Arduino Mini Pro and a simple DS1307 RTC board housed within the clock itself. Originally, it had a conspicuous external box that housed the electronics and power supply that has now been rendered obsolete — or ready for re-purposing another day! Code for the Arduino is an efficient few lines using a pair of libraries. All it needs to do is flip the polarity of the electromagnet motor every minute to update the time.

We like an elegant hack once in a while and sometimes retro tech lends itself to exactly that.

4 thoughts on “Retro Flip Clock Gets A Retrofit

  1. Funny, I did the exact same a few months ago, although with an ESP, which gets time over NTP and has a web interface for entering the displayed time so the clock can forward itself to the correct display…

    For powering the coil with alternating polarity I used a L298N breakout board I had lying around…

    These clocks are essentially driven by a low resolution stepper motor (1 step per minute) and are driven by a master clock. Many of these clocks are typically connected in parallel to one master…

  2. West german clock? For me it is a Solari Cifra 12 clock, made in Italia. Sometimes the local reseller can also add its own brand, in addition to Solari’s one.

    Also, this design is quite basic, since there’s nothing to help adjusting the time when needed (neither locally with manual switches or remotely with wired/wireless interface). I think it is quite mandatory since this kind of clock can’t flip its digits backward, and this one is also hanging at the ceiling.

    CuriousMarc (who is well known here at least for its Xerox Alto restoration) has already made a much more impressive restoration of a Dator 10 (hour + date clock from the same manufacturer), with a fancy LCD interface.

    You can also find premade driver, like

    This kind of driver is also needed for other “slave” clocks, like traditionnal round shaped ones.

    And this kind of “impulse” driving signal is still used today to drive multiple clocks at a time from a master clock (but there are now more modern digital protocols like AFNOR, DCF, NTP…). For example: or

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