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Rainfall Detector Alarm using 555 Timer & Rain Sensor
555 Timer Project – Rainfall Detector Alarm using 555 Timer & Rain Sensor is a mini electronics project for Electronics Students.
The main component of this rain alarm is rain sensor. Whenever the rain drop would fall on rain sensor, it will short the point A and B and a voltage would get applied on the base of Transistor, and it will become ON.
It is a very simple rain alarm circuit which is designed using mainly a transistor, water sensor and a 555 timer IC.
The components required for designing Rainfall Detector Alarm using 555 Timer & Rain Sensor are as follows:
1. 555 timer IC 2. Rain Sensor (You can design by yourself) 3. Transistor - BC147 (any NPN transistor) 4. Buzzer 5. Capacitors - 10uF 6. Resistors - 470E, 1K, 4.7K, 100K (2 nos) 7. 9 Volt Battery
The Circuit diagram of the project is given below. Assemble the circuit as shown in the circuit diagram.
Working of the Circuit
Whenever there is a rain, rain drops falls on the rain sensor, and as you can see in the diagram of rain sensor, water on rain sensor would short the Point A and B. As soon as Point A and B become short, a positive voltage would get applied on the base of Transistor Q1, through the resistance R4. Because of the voltage at the base, transistor becomes ON (initially it was in OFF state), and current started flowing form collector to emitter.
Now Reset PIN 4 of the 555 Timer, gets a positive voltage and 555 timer IC becomes ON and Buzzer starts beeping. Here we should note that initially there was no positive voltage at Reset PIN 4 of 555 IC, as it was connected to the ground through resistance 4.7k and 555 IC only works when Reset pin gets positive voltage. Here we can see that 555 Timer IC has been configured in Astable mode so that Buzzer generate a oscillating sound (means periodically on and off).