Rain Sound Generator Circuit

The project described here is of “Rain Sound Generator Circuit” which is simple and uses ordinary components. It comprises two oscillators: one is a variable low-frequency oscillator that uses UJT 2N2646 (T1) and the other one uses timer IC NE555. A single UJT (Unijunction Transistor) can be oscillated without using a tank coil. The electrical characteristics of UJT are quite different from ordinary bipolar transistors. 

The second oscillator using timer IC NE555, IC1 is in astable mode. Here, T1 acts as the noise generator for the circuit. The sound produced from the circuit containing the UJT is given as input to the IC1 via its pin 4. But if UJT does not conduct, pin 4 of IC1 becomes inactive. So the operation of 555 depends on the conduction of UJT. The amplification is carried out and its output is fed as input to the capacitor. The capacitor then gives out the sound produced and is heard by the human ears from a device that converts the electrical energy i.e. the electrical signal to sound energy. In this way, a new type of sound, i.e. the sound of rain, is generated from the speaker.

A simple 9V DC unregulated power supply can be used. The project Rain Sound Generator was successfully tested with a power supply unit using 0 – 9V, 500mA step-down transformer, four rectifier diodes i.e. 1N4001, and a 1000 µF, 16V capacitor.

The Rain Sound Generator circuit has been said to be first discovered and implied by Japanese researchers. With so much time spent in front of screens, people have tended to develop various disorders associated with eyes and sleep. The blue rays coming from the screens tend to inculcate sleeplessness in us. And as an alternative to pills for insomnia, the rain sound generator has been one of the useful applications to aid people with insomnia with its relaxing effect. The sound of the rain is known to relax our brain, calm us, and in some cases, act as a tonic for anxiety as well.

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PARTS LIST OF RAIN SOUND GENERATOR CIRCUIT

Resistors (all ¼-watt, ± 5% Carbon)

R1, R5 = 47 KΩ R2 = 100 Ω R3 = 47 Ω R4 = 1 KΩ VR1 = 100 KΩ

Capacitors

C1, C2 = 0.04 µF (Ceramic Disc) C3 = 0.01 µF (Ceramic Disc) C4 = 100 µF, 12V (Electrolytic Capacitor)

Semiconductors

IC1 = NE555 (Timer IC) T1 = 2N2646 (silicon PN Unijunction Transistors)

Miscellaneous

LS1 = 8Ω, 0.5W 5 cm speaker