This document describes an automatic rain sensing wiper system using a 555 timer circuit. The system uses a rain sensor that activates when water drops are detected. This triggers the 555 timer circuit, which turns on a transistor. The transistor then activates a relay that powers the wiper motor, causing the wipers to turn on when rain is falling. The system automatically detects rainfall and activates the wipers to clear the windshield without manual operation. It can provide convenience but requires additional installation costs for vehicles.

1. ‘

2. AUTOMATIC RAIN SENSING WIPER SYSTEM USING
555 TIMER

3.  A rain sensor or rain switch is a
switching device activated by rainfall.
RAIN SENSOR

4. How rain sensing wipers work?
• Working of this circuit is same as the working principle of mono stable multi
vibrator. Here the trigger to the second pin is given by rain sensors.
• A small water drop on the rain sensor will connect the negative voltage to the
trigger pin of 555 IC which in turn will turn the output pin of 555 high.
• 555 Output is connected to the base of transistor through a 1K resistor which
forward biases the transistor. Thus relay gets negative and it switches ON the
wiper motor.

5. The schematic circuit is:

6. The circuit mainly consists of
1.555 timer.
2.A rain sensor.
3.5 pin 12 V Relay.
4.A wiper motor.
5.Transistor(BC548).
6.Resistors(1k,10k,1M),Capacitor(0.1
micro farads).

7. RAIN SENSOR
555 TIMER
RELAY(12v) BC 548 WIPER MOTOR

8. Functioning:
Relay:
• Relay is also a switch that connects or disconnects two circuits.
• But instead of manual operation a relay is applied with electrical signal, which in
turn connects or disconnects another circuit.
Rain sensor:
• A rain sensor or rain switch is a switching device activated by rainfall.
• A small water drop on the rain sensor will connect the negative voltage to the
trigger pin of 555 IC which in turn will turn the output pin of 555 high.
Wiper motor:
• A wiper motor is used to wipe off the rain water on the glass with the help of
the principle that is "when ever a current carrying conductor is placed in a
magnetic field, it experiences a mechanical force“.

9. MERITS:
• Wiper automatically gets activated
when there is Rain or if there is
some water on the windshield.
• This circuit automatically detects
the rainfall and activates the wiper
to clear the windscreen.
• This system can be implemented in
common economic cars.

10. DEMERITS:
•This system is applied in case of water
falling on glass only.
• Addition charges are required to
install this system
to four wheelers.

12. PROJECT GUIDE: B.SRUTHI MAM
CH.SATHYA(466)
S.MAHESH(4A4)
CH.AMAR (467)
N . RAMU (497)