A simple and at the same time good doorbell you can assemble do it yourself. For a very low price, the seller offers a complete designer kit for self-assembly of an oscillation generator based on the NE555 timer chip. The package includes a printed circuit board, a dynamic head, and actually all discrete elements for assembling a call. For safer sealing, there is a block for the chip, thanks to which you will not overheat the timer, because it will simply be inserted and there will be no contact with the tip of the soldering iron.
For greater convenience, the small clock button is replaced by a large, convenient to press and displayed in the right place with the help of wires. There is no circuit in the kit, but this is not a problem, since all electronic Elements are signed by silk-screen printing directly on the board. The speaker is very common in Chinese products, it is small, although it is quite loud.
The dimensions of the finished device 39 to 35 mm. It is necessary to feed the circuit at least 5 V, it is possible to use a transformerless power supply with a ballast capacitor. When using the crown, the sound is too high, the voltage source of 6 V is ideal. The call is activated by a single click on the button without fixing - a changing sound sounds for about 1 second.
Cost: ~ 57