DIY Simple Electronic Project- RAIN ALARM

Diy simple electronic project - Rain Alarm is a simple project to detect the rain. When rain starts, RAIN ALARM produces an alarm sound so that we could take necessary actions and also save rain water.The major component in this simple project is the Rain Sensor. A mica or bakelite sheet along with an aluminum wire is used as the rain sensor. It is arranged as shown in the figure below. Note that, the aluminum wire should  be pasted properly and avoid gaping between the sheet and wire. Instead of this you can use readymade rain sensor module. 

This Rain Sensor is connected to the main circuit, so that the voltage should pass through this rain sensor’s wires. In normal conditions (if there is no rain), the resistance between the aluminum wires will be very high as a result there is no conduction between the wires. When it rains, water drops falls on the rain sensor, which decreases the resistance between the wires. As a result wires on the sensor sheet starts conducting and trigger the NE555 timer IC through the transistor circuitry. 

Working Principle Of Diy Simple Electronic Project - Rain Alarm :

Check out the Rain Detector Project before making this Rain Alarm.

This is a simple project. Actually it is a Diy project. Any electronics student or hobbyist can make this project without much effort. When there is rain, the Rain Sensor's wires start conducting. Since it is connected to the Rain Alarm’s circuit, the transistor Q1 will get turned ON and LED D1 starts glowing. At the same time Q2 will also be turned ON. When Q2 reaches its saturation state, the capacitor C1 will act as a short and make the transistor Q3 to be conducting. The RESET pin of 555 Timer IC is connected to the emitter of Q3. When Q3 reaches its saturation mode, it will assert the RESET pin of Timer IC to High or Positive.  As a result, it will generate a pulse in the OUT pin 3 of 555 Timer and make the speaker to produce alarm. The 555 Timer IC is configured to operate in astable mode.  A capacitor C4 is connected between the speaker and OUT pin3 of timer IC. This capacitor blocks the DC and unwanted components to the speaker.Depending on the time constant RC (R4, C1), after some time, the transistor Q3 will get in to cut off. The time period for the speaker to make sound is depends on the R4 and C1 values.

Fig.1 RAIN SENSOR

Fig.2 Circuit Diagram Of Rain Alarm:

Electronic Components :

• Timer IC 555: 1 No.
• Speaker: 0.01uF
• LED,D1: 1No.
• Diode,D2: 1N4148

Transitors:

• Q1,Q2,Q3: BC148

Resistors:

• R1,R2: 270K
• R3: 10K
• R4: 470K
• R5: 3.3K
• R6: 3.3K
• R7: 68K

Capacitors:

• C1: 220uF/12V
• C2: 100uF/12V
• C3: 0.01uF
• C4: 100uF

Applications of Diy Simple Electronic Project - Rain Alarm :

• water leak detection  in industrial or automobile fields
• Can be used on the wind shield of vehicles to control the wipers             
• Irrigation sectors
• Home automations fields
• Communication fields

Note:  The Rain Sensor of this simple project should be placed in open areas or in places such that, an inclination of 35 to 40 degrees from the ground is obtained. This is to avoid the presence of water drops on the rain sensor for a long time. The LED in this DIY project circuit will glow until the rain stops. But the alarm will be automatically switched OFF after some time, which depends up on the time constant RC.

This is a simple electronics project for engineering students or an electronics hobbyist. It is very simple to design and demonstrate. Also you can do it as your mini projects or else.