PENDULUM

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An electric swing is a good gift for a child, and with a solid assembly, you can develop the idea to, for example, an office souvenir.

The basis of the toy is a simple overhanging circuit (although it is certainly better to make it on a circuit board), consisting of a transistor, a diode and a specially wound coil, hidden in the bottom. The “seat” of the swing is a magnet, it’s better to choose a neodymium one, now it’s full, although the usual one will do.

The coil is winded by a double wire with a cross-section of each approximately 0.25-0.3 about 1500 turns, i.e. 2 copper wires are taken in parallel and wound on a reel. The diagram shows that the end of the first wire is connected to the beginning of the second. I chose the oval shape for logical reasons, because a magnet passing over it will interact better along the length of the larger diagonal of the ellipse. The core is not used, so you can experiment with it. It’s better to wind it carefully, turn to turn, but not necessary.

Direct conductivity transistor, you can take the MP39 ... 42, any diode, the usual battery at 1.5 volts. For convenience, it is better to make a switch.

I apologize for the handicraft assembly, but I did it in my school years on bare enthusiasm according to the scheme from the old father’s notebook with schemes, so I really did not know where it came from, and I just wanted to see how it works as soon as possible.

It starts simply, turn on the device and push the magnet, after a couple of seconds you will notice how the pendulum begins to oscillate. The system will work better if you can create a resonance, i.e. the equality of the frequencies of the circuit and the natural frequency of the pendulum, which is calculated by the formula. Here, this is achieved by fitting all the parameters of the pendulum. It is better to fix the connecting rod on 2 bearings, and not on the 1st one, like mine.