Making a UNIX Clock While Making a Few Mistakes Along the Way


Sometimes the projects we think are easy to design are the ones on which we end up making the most mistakes. The UNIX clock that you see in the picture above is one of these projects. For our readers that don’t know it, UNIX time is the number of seconds since 00:00 on January 1st 1970. The clock that [James] designed is based on an Arduino Pro Mini board, an RTC chip to store the time, a custom made display board and two buttons to set the date/time.

One of the mistakes that [James] made was designing the boards on which will be soldered the seven-segment displays before actually choosing the ones he’ll use, as he was thinking they’d be all the same. The displays he ended up with had a different pitch and needed a different anode voltage, so he had to cut several traces on the PCBs and add another power supply. It also took [James] quite a while to remove the bits that his hackerspace’s laser didn’t cut through. We strongly advise a good look at his very detailed write-up if you are starting in the electronics world.

If you find this Unix time display too easy to read here’s one that’s a bit more of a challenge.


  1. Truth says:

    Why ? Has he never heard of the Y2K38 bug.

    • Sven says:

      what happens year 2380?

      • Y2K38monster says:

        It’s when all the seconds are gone. Or you travel back in time to December 13, 1901. Whichever.

      • Rob says:

        the Y2K bug was because of a limit of 2 decimal places obviously in decimal. ie there was no distinction between 2000 and 1900 as only the 00 was stored.

        Unix time is binary and has a fixed binary width that limits it to storing from 1970 to 2038. After that it becomes 1970 again. Most web servers use unix time.

        • Sven says:

          Yes i know that, i was making fun of the use of Y2k38.

          the ‘k’ in that syntax usually means a decimal, and then the whole number multiplied by 1000. 2k38 would be 2.38 * 1000 = 2380. Not 2038.

          The system is usually associated with component value markings where decimal points could easily get misprinted or rubbed off, and space is limited. A component value of for example 2.9 megaohms could be written as 2M9.

    • fowkc says:

      The time is stored in this project as a uint32_t, so it’ll last until 06:28:15 UTC on Sun, 7 February 2106.

      If the clock itself lasts that long, I’ll be well impressed.

  2. cf says:

    Aw, from an NYCResistor memory – the NYC-time clock is awesome!

  3. In the image we see Unix Epoch 1382731413 which is Fri Oct 25 16:03:33 2013 EST, but the analog clocks on the wall are showing 10:07 and 2:34.

    This is triggering my OCD.

  4. Here is how you use the word “an” as opposed to “a”

    For words that start with U, it depends on the way the word sounds. If ‘U’ is pronounced ‘you’ like US ‘you-es’ then you use “a”. If ‘U’ is pronounced like ‘uh’ like uprising ‘uh-pry-zing’ then you would use “an”.

    Thus, UNIX ‘you-nix’ would be “a”. Making a UNIX Clock While Making a Few Mistakes Along the Way.

  5. WBailey says:

    FYI Carbon monoxide is heavier than air, not sure you want your CO detector up real high like that.

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