Theremin

Here's a toy soldered by my amateur radio father. What is this tricky device? This is theremin.
A bit of history, of course, needs to be told. The first theremin was created in 1908 by the Russian scientist and musician Theremin, from where it got its name. The principle of operation is simple: depending on the lighting, the device makes peculiar sounds. Thus, it can be considered the first musical power tool.


What my father did cannot be called a real theremin, it is most likely a toy on a photoresistor, but still interesting. This is due to the fact that the sound that is produced at the output is polyphonic, and Theremin theremin was monophonic.
Making this miracle device is not very complicated. You only need to go to the nearest radio store and buy all the necessary parts, and their price is honestly not so high. Or you can disassemble your old Chinese tape recorder, where you will find half the details.


For the convenience of soldering and manufacturing, it is better to buy a breadboard printed circuit board. Just the process of drawing tracks, and then etching them, will take an indefinite period of time. A ready-made breadboard will speed up the process and you can make this device yourself literally in the evening.
Because it’s not his own invention, he worked according to this scheme, and, of course, slightly modernized it to make the device work better and look modern. An audio output, an on-off button and a volume control were added to the device.
This device works on the basis of a 555-chip or as it is also called a "timer".


Using a photoresistor, the pitch is modulated. It all depends on the illumination of the room. With hand movements, you either close the light access to the photoresistor, or open it. This device works on a regular battery like a crown.