A device called the EM 2 electromegaphone was produced back in the Soviet Union and was powered by large batteries. These are popularly known as square batteries or flashlight batteries. They have a format 3R12Their voltage is approximately 4.5 volts. For the speaker to operate, as many as six of these elements are required.
Currently, power sources cost around 100 rubles each. You might be able to find them a little cheaper, but it's unlikely they'll cost less than 30-50 rubles. So, bringing this toy back to life will cost you around 500 rubles. But will your device even be functional after years of dormancy? That's the big question.
Inside the square element there are 3 batteries of 1.5 volts. Externally they resemble AA batteriesIn principle, you could use 18 AA batteries instead of 6. It might be cheaper, and they're generally easier to find.
In general, you can assemble some kind of power bank and power them from this assembly.
