Posts with «random» label

Follow the Bouncing Ball of Entropy

When [::vtol::] wants to generate random numbers he doesn’t simply type rand() into his Arduino IDE, no, he builds a piece of art. It all starts with a knob, presumably connected to a potentiometer, which sets a frequency. An Arduino UNO takes the reading and generates a tone for an upward-facing speaker. A tiny ball bounces on that speaker where it occasionally collides with a piezoelectric element. The intervals between collisions become our sufficiently random number.

The generated number travels up the Rube Goldberg-esque machine to an LCD mounted at the top where a word, corresponding to our generated number, is displayed. As long as the button is held, a tone will continue to sound and words will be generated so poetry pours forth.

If this take on beat poetry doesn’t suit you, the construction of the Ball-O-Bol has an aesthetic quality that’s eye-catching, whereas projects like his Tape-Head Robot That Listens to the Floor and 8-Bit Digital Photo Gun showed the electronic guts front and center with their own appeal.

Filed under: Arduino Hacks


The Chaot is my contestant for the LMRv4 Donor Appreciation Robot Challenge. 

The machine creates a random number using physical chaos and combines the random numbers to an four digit index.
This index can be used to select a winner.


  • Draw Winner Using a Magnetic Pendulum
  • Idea Finding
  • The Making-Of
  • Used Parts
  • Current Issues
  • Thanks To
  • Further Reading

Draw Winner using a Magnetic Pendulum

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Let's Make Robots 27 Apr 09:18