Instructables: Build An Optical Theremin

An Instructables by Sacred

Table of Contents
Intro: How To Build An Optical Theremin
Step 1: Gather Materials!
Step 2: Putting it together
Step 3: The Finished Product and Video

Intro: How To Build An Optical Theremin

Instructables Logo
What is a theremin? It is an instrument that can be played without being touched. Traditional theremins use antennas and oscillators to sense a person's hand and generate a tone. Ours will use light instead. Because of this, it is not an actual theremin, it just uses similar principles. As a side note, this is my first instructable, so please be nice.

Here is a video of a real thermin:

This is where I learned how to do this:

The original optical theremin

Original Optical Theremin

Step 1: Gather Materials! (top)
This needs very few parts, I made mine for under $20.
Here is what you need:

Tools List Mfr P/N Jameco P/N
Two phototransistors UT1893-91-0125-R 373001
One TLC555 timer IC TLC555CP 761272
One .047µF capacitor DC.047B 1947351
One 100µF capacitor RA100/16-R 330422
One 1MΩ resistor CF1/4W105JRC 691585
One 10kΩ resistor CF1/4W103JRC 691104
One Battery pack (to fit 4 AA) SBH-341-1AS-R 216187
Four AA batteries ALK AA (EN91) 198707
Hook-up wire #9313-0-R 36792
One breadboard WBU-301-R 20601
One small speaker KWT2340F12L-2E 336314
Wire stripper JE-2022C-R 215889

Image Notes
1. These are not LEDs. They are phototransistors. Make sure you get the right thing!
Image Notes
1. 1MΩ Resistors
2. 10kΩ Resistors

IC Socket
Image Notes
1. The TLC555 IC timer. Mine is an IC socket. I recommend getting a socket for your chip.

.047µF Capacitor
Image Notes
1. The .047µF Capacitor. It reminds me of chicklets.

100µF Capacitor
Image Notes
1. The 100µF capacitor

Battery Pack and Breadboard
Image Notes
1. My battery pack. It has an on/off switch built right into it. Very convenient.
2. This is a breadboard.

Image Notes
1. Wire! I got mine from telephone line. Its sold by the foot at most hardware stores for a low price, and when you strip off the outer casing, theres 4 strands of wire inside.

Image Notes
1. My cheap little speaker. It's terrible, but it manages.

Step 2: Putting it together (top)
This is a really easy circuit to build. Just make sure you follow the directions. If any problems come up, I'll gladly try to help you out. Just send me a message. And yes, the image came from It's a fascinating website.

RS Optical Theremin

Step 3: The Finished Product and Video (top)
At this point in the game, everything should be working. Congratulations on the build, have fun with it!

Optical Theremin

Jameco welcomes the contributions of its customers. Frankly, we think what you write is more interesting than anything we could write. Share your electronic component story, project, or challenge, and we'll share it with the world. Send your story to