Clock knock box – a useless machine


This Clock Knock Block can do a lot of things: milling, Arduino, sensing, solenoids, and plenty of dirty puns. Just knock on the Knock Block, or even the surface on which it’s resting, and it will knock back the time to you. First it will knock the number of hours, and then the quarter hours.

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

Parts list:

  • – any Arduino can handle this
  • – a TIP31C high current transistor for the switch
  • – the exotically named Jameco 191172-001 solenoid, prized for its low price ($3!) and current
  • – a Measurement Specialties DT-series piezo film element (pretty sure that’s the model)
  • – a 1M ohm resistor (your mileage may vary)
  • – 9V battery
  • – block case of your choice

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.

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