Make your own Atomic clock

We see plenty of clock projects come through, but usually it is their visual or mechanical design that stands out. The DCF-77 LED PIC clock is fun because it is synchronized with the Atomic clock in Braunschweig Germany. The clock picks up the radio signal at 77.5 KHz known as DCF77, and that’s where it got its name.

The circuit looks surprisingly simple and usually costs less than $30 to build, depending on how you piece it together. You can download the schematics and code from the site, but you may have to do a little research about how to catch the signal from your location. The person who wrote this was located in Europe.

[found via HackedGadgets]


  1. Mrok says:

    Make your own Atomic clock?

    Next week on Hackaday: Make you own Atomic Bomb!
    (actually just a crappy arduino hack that allows you to display video of an atomic explosion on a crappy nokia phone display)

  2. Tokamak says:

    The title of this post is misleading.

  3. Stefan says:

    Agreed. This is making an atomic clock like buying a laptop is making the internet.

    Not to say this is not a useful trick. If commercial clocks used this for say a dollar per unit, we would never have to set a clock again.

  4. spuder says:

    Two standards exist for “Atomic Clocks”
    The DCF-77 for europe and the WWVB for the United States. One of my first blog posts covered signal issues with my word clock that I encountered trying to get the time from Fort Collins Colorado.

  5. thatcherc says:

    Still, anytime something with the word ‘atomic’ comes up on HaD, it’s bound to be fairly interesting.

  6. mjrippe says:

    To “make your own atomic clock” you can buy a Rubidium frequency standard on ebay for US $60-80 including shipping.

  7. xphera says:

    Also agreed with tokamak and stefan.

    Stefan, actually they do. The clock I have been using for 9 years has this function:

  8. In the USA, the corresponding longwave time signal is called WWVB. A groundwave is preferred over shortwave skip because the radio wave path is constant and predictable.

    WWVB isn’t to hot a signal on the east coast though.

    The real advantage in a clock like this is that it can be made to set itself and deal with daylight savings time. Aside from that though, seriously, for clock/radio/alarm level precision you can usually trust the power company to issue 5,184,000 power peaks per day, and then just divide that down.

  9. Deckert says:

    Very nice. What I’d really like to see is a clock that transmits the WWVB or DCF signal. In my country there is neither of these signals, but I do have several gadgets that can “listen” for these signals.


  10. kubik says:

    Keep on mind this will only work in Europe, and only in reasonable distance from the sender.
    Commercial clocks with this receiver are available for a couple of bucks, and I’ve even seen wristwatch using DCF77.

  11. anon says:

    Are there any good WWVB receivers available? Digikey used to sell one, but they’re out of stock and I haven’t been able to find it (or an equivalent) anywhere else.

  12. Dan says:

    These days, synchronization via DCF-77 is a really common feature for alarm clocks, weather stations and wall clocks here in Europe. Cheap DCF-77 clocks (“Funkuhr” in German) can be bought for around 10€. So, you’re essentially saying that there are a few million atomic clocks around here ;)

  13. Jamen says:

    honestly, it’s 2012. why doesn’t every appliance in my house to have one of these in it already.

  14. echodelta says:

    Has the rest of the world gone on night time robing time like the US, or is the time soon. We shifted two weeks ago and on cue we went from frosty to eighty’s overnite and kept it going till yesterday.
    My way of protesting this situation with clocks is to use UTC.
    It’s fun to hear voice time on WWVB and WWVH mixing together on 10 or 15 mHz, and hear him (Colorado) and her (Hawaii!) pipping along out of time like John Lennon’s Give Peace A A Chance clap track.

  15. nobody says:

    The atomic clocks behind DCF77 are located in Mainflingen and not in Braunschweig! The longwave transmitter is operated by T-Systems.

  16. veh says:

    Nice, I’m from Braunschweig, Germany. :)

  17. INquiRY says:


    The official German time is kept in Braunschweig at PTB, the German metrology institute (check their crappy website at
    The time broadcast over much of Europe from near Frankfurt is using commercial atomic clocks that are synchronized every now and then with the big one at Braunschweig.

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