Build A Photo Theremin From 7 Parts!

This is a demo of Forrest Mims, III’s Audible Light Meter.┬áThis photo-theremin design was originally published in Optoelectronic Projects Vol 1, published by Radio Shack in 1976.

The schematic is included within the video.

via EA78751:

a super minimal photo-theremin from back in the day… lets build it and see what it sounds like.

it only has 7 parts including the speaker and battery!

2 thoughts on “Build A Photo Theremin From 7 Parts!

  1. Just wonder if the “light resistor” is being used as a resistor or a switch. Dose the setting of light coming in to the resistor change the amount that can pass, just just lets it all flow, and turning on the Transistors to max flow

  2. Interesting. I need to check the clarity of Hydraulic fluid in a sight glass of 15 mm diameter.
    By using a LED ( or IRLED) as a light source from one end of the glass / transpairent tube and the sensor on the other end will i be able to get a signal or lack of signal once teh fluid starts turning black or a diffrent colou (darker) ?? Please help and advise. Does some one have an alternate circut??. voltage available is 5 v dc / 12 v dc

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