Clock knock block full of puns


This Clock Knock Block has a bit of everything; milling, Arduino, sensing, solenoids, and plenty of dirty puns. Just knock on the box or on the table right next to it and the time of day will be played back to you in a series of crisp, clean knocks. A big part of the fun here is that the box is a musical instrument.

If you take a look inside you’ll find an Arduino, a piezo sensor, a solenoid, and a nine-volt battery. The piezo sensor detects your knocking as an input. It can even listen to and repeat back a series of your knocks. The Arduino actuates the solenoid, which strikes the wooden enclosure, producing the knocking sound.

We’ve embedded a video of this useless machine after the break (that’s where all the puns are). One note for your own build; this box is made out of mahogany and because it is used as a resonance chamber, this may not work as well if it isn’t milled from a piece of quality lumber.


  1. Caleb Kraft says:

    gotta love puns.

  2. Justin says:

    Who made the video? Dr. Seuss?

  3. moore850 says:

    I own a real instrument like this, and if it weren’t a family heirloom I might try to convert it to one of these :)

  4. imgreen says:

    im interested in the portion of code that records a sequence of knocks and replays them… looking at the instructable site i dont see that mode in the code. could someone clue me in on how this is done?

  5. imgreen says:

    oh, would fans of this device be the knock block flock?

  6. lolknockblock says:

    so when a chick doesn’t want to sleep with you because she thinks you are such a deuche for having one of these.. is that a knock block cawk block?

  7. japkin says:

    I like it! Cool but useless!

    Next step…embed a small screen at the top and have it interpret morse code on the fly, displaying each letter as it “hears” it.

  8. Love it :)

  9. Skitchin says:

    If you knock “shave and a haircut”, will it knock back “two bits”?

  10. Skitchin says:

    lol ok I admit, I just now watched the video ;\\\\\

  11. Steve says:

    I didn’t really see any puns in the video. Maybe I just didn’t get them? I did see (hear) a lot of alliteration, though.

  12. imgreen says:

    silly steve, starting sound signifies alliteration.

    constant consonants correctly classifies alliteration.

    seriously, ‘someone’ should seek supplementary study of sentence structures soon…

    but it ain’t no crime to mix-up alteration and syllabic rhyme.

  13. Adam Wolf says:

    imgreen, I’m half of the duo that produced the tactile metronome kit that works like this.

    We wrote up how we implemented pattern detection at

  14. imgreen says:

    @adam wolf

    Thanks for chiming in. I have an idea for this functionality, but being new to coding it takes me a bit to catch on. I saw your metronome a while back and wanted to know how that was done… very cool. Thanks for the link — I’ll spend some time reading up….

  15. napalm says:

    @lolknockblock, that’s effin hilarious!

  16. luke says:

    i like it !
    it is very cool.
    the only thing i would change would be rather than haveing one knock for every hour and one knock for every quarter hour.

    i would have one knock for every hour, one for every 10min block and one for every single minute

    but a fantastic idea and you guys pulled it off !

  17. Griffco says:

    Das is de knockwurst!

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