Ding-Dong Doorbell with NE555 Chip - DIY Kit

There is an integrated circuit that, despite being produced for half a century, has not become outdated and its range of applications is so wide that many books have been written about it.

Meet the NE555 timer!

This is a self-assembly and soldering learning kit.
Easy to assemble.
Assembly time 1 hour.

Functional Description:

This circuit is a multi harmonic oscillator composed of 555 integrated circuit. When SW1 is pressed, the power supply charges C2 through D2. When voltage of the four pins (reset pin) of integrated circuit U1 is greater than 1V, the circuit oscillates and a "ding" sound is emitted from the speaker. When SW1 is released, the electrical energy stored in the C2 capacitor is discharged through R4 resistor but the four pins of the integrated circuit continue to maintain a high level and maintain oscillation. This is because R1 resistor is connected to the oscillation circuit, the oscillation frequency decreases, causing the speaker to emit a "dong" sound. When the electrical energy on the C2 capacitor is discharged for a certain period of time and the voltage of the 4 pins of the integrated circuit is lower than 1V, the circuit will stop oscillating. Press the button again and the circuit will repeat the above process

Instruction:

The systems have an assembly diagram printed on the board. You need to pay attention to polarity in the case of elements such as capacitors, diodes, transistors. In the case of LEDs, the longer leg is plus +, most elements have their parameters described on the housing. Resistors may have stripe markings, their resistance and tolerance can be read using calculators available on the Internet or measured with a multimeter. The assembly order is usually arbitrary, depending on the layout, we assemble the smallest elements first.