Rain Detector

Rain Detector:

Rain detector or rain sensor is a circuit that is used to detect or sense rain i.e. as soon as the rain droplets fall on the sensor it triggers an alarm or a buzzer or any other device that is used to indicate the presence of rain (water).

Specified Problem:

The problem given was to make a rain detector circuit that glows an LED when there is no rain droplets or water on the sensor and when it rains i.e. is water droplets are present on the sensor it turns of the LED that was previously glowing to show the absence of rain and then simultaneously turns on a BUZZER and another LED which indicates the presence of rain or water droplet on the sensor. Moreover the BUZZER and the LED (used to indicate rain) was to glow and buzz with some constant time interval i.e. it remains on for some  certain time (seconds) and then goes off for some certain time(seconds) and then goes on again repeating this until the rain or water droplets are present there.

Designed Circuit:

The problem given was solved by designing a circuit which works according to the given specification i.e. the switching between the two LEDs was achieved by using a SPDT (Single Pole Double Through) RELAY and the timing of the buzzer and the other LED was achieved by using the 555 timer IC.

Components Used:

·   Relay

·   555 Timer IC

·   Resistors

·   Capacitor

·   LEDs

·   Sensor

·   DC supply

·   Buzzer

Working:

The circuit connected as in the circuit diagram given below. The connections are done in such a way that one leg of the relay is directly connected to 12Volts while one leg is connected to 12Volts via sensor, one leg of the relay is connected directly to ground while the remaining two are connected to the LED indicating the absence of rain and the other to the LED and BUZZER indicating the presence of rain respectively. The arrangements made on the legs of relay are made in accordance to the circuit diagram and the relay connections.

When there is no rain the 12Volts which are directly connected to the rain passes through the relay and via resistor turns on the LED to indicate the absence of the rain or water.

As soon as the rain or water droplets are detected on the sensor the circuit is completed and the current flows through the sensor which magnetizes the coil of the relay thus it shifts to its second through which is then connected with the buzzer and the LED (used to indicate the presence of water or rain) via resistor, when this happens the current flows through this half of the circuit thus causes the buzzer and the LED to glow and indicate the presence of rain , the timing of the buzzer is achieved by the 555 timer IC which is given above in detail.

The circuit again turns to the original state of no rain when there is no rain or water on the sensor i.e. the rain has stopped and the sensor is dry.