Master Clock System Uses All Logic, No Microcontrollers

What you see above is a master clock. It is the center of a system that can run an unlimited number of slave clocks, keeping them on-time thanks to its ability to synchronize with an atomic clock. [Brett Oliver] put together the project back in 2005 using digital logic chips, and no programmable microcontrollers. This includes everything from the binary decoders that drive the 7-segment displays, to the radio transceiver board that gathers the atomic clock data, to the various dividers that output 1 second, 2 second, 30 second, 1 minute, 1 hour, and 24 hour signal pulses. It’s  a well document and fascinating read if you’re interested in digital logic clocks.

17 thoughts on “Master Clock System Uses All Logic, No Microcontrollers

  1. I was thking of bulding one of these, but I want to use GPS as the source. Any idea on the best way to use it to synchronize it with multiple windows xp and windows 7 machines?? I’ve tried time servers but they all fall off from 1 to 5 minutes ever 24 hours…..

  2. It need’s be voiced with trumpet and drum.
    This is well past craft,
    And measures only to a precious art.

    HAD needs a Hall of Fame and Inspiration,
    And this should occupy the foyer.

  3. I was just thinking about building a master clock an hour or so ago, for some slave clocks I got on ebay 10 years or so ago and still haven’t gotten around to making use of; was thinking of some kind of ethernet-and-atmel contraption (ethernet for syncing to Internet time). Quite a coincidence. This got me thinking though, I have a pair of logic-based LED clocks my dad built back in the 70s (one for local time, one for GMT). Maybe I could put a once-a-minute FET output on one of them somehow. But those never kept very good time… I’ve always wanted to figure out a way to automatically set them periodically, and keep the two in sync as well.

  4. Yes it’s kind of a masterpiece and highly impressive but a single microprocessor with a few peripheral ICs would be much more reliable. Fewer components, less wiring / connections, probably a single PCB.

    I’m not sure but it looks like he sells these clocks (for a lot of money)? I would be concerned about EMC if this is to be sent out to customers. Has it been tested? Not sure how the perf board would hold up…

    An amazing project for a hobbyist but judging by the quality of his work it looks more commercial.

  5. @sashmo:
    NTP is the way to go, but do not use the daemon that comes with windows, microsoft says it isn’t meant to be used for really precise use. If your internet connection is somewhat predictable there souldn’t be a problem with using the timeservers. If your local clocks run off, maybe sync more often or find a machine that is more stable and sync the others off it (NTP in a local network is more stable than over the internet and you can sync very often, timeserver operators do not like it if you sync with them too often)

  6. Thanks for the comments, here are few notes on the background to my clock. I am a telecommunications engineer and served my apprenticeship on electromechanical exchanges in the late 70s.

    This clock was inspired by construction methods we used in exchanges in the 70s & 80s i.e. all components hand wired and all wiring laced with waxed twine (no plastic zip ties). To me the wiring of the components with thousands of wires is a dying skill. The clock should look as good open as it does when closed. Yes it could be built with a few PICs ( I have used one in my Calendar clock) but it just would not look the same.

    It is a 1 off and non commercial and was posted as a collection of ideas. I am sure no one will build the whole clock but may find some of the ideas useful.

    The clock and slaves are very reliable and keep in sync with the DCF77 signal from Germany perfectly.

    Long live Comic Sans.

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