DEPARTMENT OF ELECTRONICS AND COMMUNICATION

RAIN WATER SENSING USING 555 TIMER

SUBMITTED BYRANJAN KUMAR GUPTA

ECE - 3rd year1322231055 Submitted To

Department of Electronics and Communication

Engineering Feb 2016

INTRODUCTION Rain alarm is an application which detects

the rain water and blows alarm. They are useful devices and play an

important role in various industries such as

automobile, irrigation, and wireless communication. Designing a rain alarm system is quite

simple and we have designed here a demo rain alarm project with the help of 555 Timer

IC.

Rain alarm is an application which detects the rain water and blows alarm. They are useful devicesand play an important role in various industries such as automobile, irrigation, and wireless communication. Designing a rain alarm system is quite simple and we have designed here a demo rain alarm project with the help of 555 Timer IC. ComponentsRain sensor (Either you can purchase or build yourself)555 Timer ICNPN Transistor BC547Resistors (470, 100k and 1k ohm)Capacitor (10uf)BuzzerBattery 9v

PIN DIAGRAM

CIRCUIT DIAGRAM (ON BREAD BOARD)

The main component of this rain alarm is rain sensor, I have purchased one, but we can also build it at home. It’s very easy to create a rain sensor. Take a sheet of Bakelite or mica, and paste the aluminum wire on it according to the diagram shown below. The Gap between the wires should be around 3-5mm. You can see that 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. We can also use copper wire for rain sensor but copper generally reacts to oxygen to form oxide, so it needs to be cleaned on regular basis.

Circuit Diagram and Working Explanation

It is a very simple rain alarm circuit which is designed using mainly a transistor, water sensor and a 555 timer IC. 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 R5 (4.7k) and 555 IC only works when Reset pin gets positive voltage. .

Rain Alarm Project Circuit Applications

In the irrigation, it will detect the rain and immediately alert the farmer.In automobiles, when the rain detector detects the rain it will immediately active the wipers and inform to the driver. In communications, it will boost the power of the antenna and increase the signal strength to send or receive the signals.

THANK YOU