3D50.XX Theremin

Concepts

AC circuits, sound, frequency

Overview

Theremins are played by moving your hands near (but not touching) two antenna. One antenna controls pitch, the other controls volume. Theremins work by creating two AC currents using two capacitors (one for pitch and one for volume). The capacitors are unusual in that one "plate" is an antenna, and the other is your hand. The distance between the "plates" (i.e. the antennae and your hands) determines the frequency of the AC currents. The AC currents are modified by internal electronics to combine the pitch and volume components, convert the pitch into a frequency audible to the human ear, and amplify the sound. The resulting signal is sent to speakers.

Details

Equipment

  • [1] Theremin
  • [1] Pair of speakers
  • [1] 3.5 mm stereo to 1/4" mono adapter
  • Extension cord (if necessary)

Classroom Assembly

  1. Before plugging in the theremin, attach its antennas, with the U-shape on the left and the straight line on the right.
  2. Place theremin on top of lectern shelf and plug it in.
  3. Connect the speakers to the "audio out" port using the stereo to mono adapter.

Script

  1. Turn on the theremin.
  2. Control the pitch of sound by moving your hand near the upright antenna. Moving your hand closer increases the pitch. You can produce vibrato by vibrating your hand.
  3. Control the volume of sound by waving your hand near the loop antenna on the side of the theremin. Moving your hand away increases the volume.
  4. Try to play a song!

Additional Resources

References

  • PIRA 3D50.XX

Last revised

  • 2018

Technicals

Related AV

Related demos

If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.