This morning I woke up very early. Nothing was on TV, the interwebs were boring me and I was not in a mood to play a video game. So I sat down at my workbench and decided to make a theremin. I remember as a child a neighbor having a tube theremin that produced those eerie high pitched notes of classic b grade horror movies. When ever we would visit their home for a cook out or party I would play with the theremin every chance I got. To me, it was the coolest noise maker ever. The fact that I could manipulate the tone and pitch of the sound with out touching anything together was simply awesome. So with a theremin project in mind I jumped back on the web and a quick search yielded me this pocket theremin project from Popular Science. It is comprised of just 9 components, all of which I had on hand. So with the schematic chosen I sat down and bread-boarded my first theremin.
The pocket theremin I chose to make is unique to me because it uses 2 CDS (Photocell / Photoresistor) to manipulate the tone and pitch of the sound generated. It operates on an oscillator and a frequency divider made from 2 555 timers. Sound volume is controlled by a 5k pot and is output to an 8ohm speaker. Even the most un experienced rookie to electronics can breadboard this circuit in under 10 minutes. This design was adapted by Popular Science from The Forrest Mims Engineers Notebook.
Now bread board up your Theremin following the schematic below.
Great! Your project should now look something like this.
Connect your 9v power source and move your fingers over the CDS cells and note the sound change. Now adjust your 5k pot for the best quality sound and have fun trying to make different sounds. Note that you can use any value of CDS cells and you should experiment for different values for different pitches and tones.