Space Music – Planetarium SynthesizerAbout 38 years ago I built a synthesizer for my planetarium and some laser shows I did. My school had no budget for the planetarium, so I had to make things for myself.
I used a calculator key pad, resistors, a 555 chip and an old speaker. I put "rubber dam" from Edmond's Scientific over the speaker stretched tight. I glued a piece of the first surface mirror on the rubber. Shining the laser at the mirror, I could project shapes on the dome.
I can see that the theremin could do the same thing with a laser pointer!
Here is the Theremin I built. My grandson calls it "Space Music". I modified the plan a little. I put in an on/off switch so the battery doesn't need to be taken off each time. Besides, he likes turning it on and off.