Analog Electronics Circuit Laboratory

Project :- Automatic rain sensing



Shashank kumar

K.S.V.K Sri charan

Department of Electronics and Telecommunication International Institute of Information and Technology Bhubaneswar (Third Semester, 2019)


1.Name of the Project

2.Materials Required


4.Circuit diagram

5.Procedure and Explanation

6.Working Concept

7.Results and Analysis



Step 2: Name of Project and Component Required




a. 555 Timer IC

b. L298D IC

c. LM358 motor driver

d. Transistor BC557

e. Resistors (1K, 10K, 2.2M)

f .Capacitors (0.01uf, 0.47uf)

g. DC Motor

h. Rain Sensor

i. Power supply (5-12v)

Step 3: Theory and Circuit Diagram

With drivers exposed to an ever increasing number of distractions, automatic rain-sensing wiper systems become an even more appealing feature, as they work to minimize the time the driver must take his/her hands off the wheel.

Most traditional systems offer intermittent as well as variable speed operation. The traditional wiper system however requires driver constant attention in adjusting the wiper speed. Traditional windshield wiper speed constantly varies according to time and vehicle’s speed. Because the manual adjustment of the wiper distracts driver's attention, which may be a direct cause accidents. This is review paper for automatic wiper in various method and also explain the basic skeleton for adjust speed of wiper automatically cording to the amount of water on the windshield and in addition with also in advance removal of moisture inside the car while raining.

The system activates the wiper to operate in full automatic mode and detect moister. On proceeding for the main part of theory we must have sufficient knowledge of the components. Few components like 555 timer IC, L298D, IC LM358 are to be deeply researched in order to complete project perfectly in least possible attempts.

Step 4: Timer 555 IC

The 555 timer IC was first introduced around 1971 by the Signetics Corporation as the SE555/NE555 and was called "The IC Time Machine" and was also the very first and only commercial timer IC available. It provided circuit designers with a relatively cheap, stable, and user-friendly integrated circuit for timer and multivibrator applications.

It operates from a wide range of power supplies ranging from + 5 Volts to + 18 Volts supply voltage. Sinking or sourcing 200 mA of load current. The output of a 555 timer can drive a transistor-transistor logic (TTL) due to its high current output. The duty cycle of the timer is adjustable. The 555 timer combines a relaxation oscillator, two comparators, an R-S flip-flop, and a discharge capacitor. However, if the threshold input (pin 6) is now raised above +(2/3)VCC, the output will return to ground and the discharge transistor will be turned on again.

When the threshold input returns to ground, the IC will remain in this state, which was the original state when we started this analysis. The easiest way to allow the threshold voltage (pin 6) to gradually rise to +(2/3)VCC is to connect it externally to a capacitor being allowed to charge through a resistor. In this way we can adjust the R and C values for almost any time interval we might want.

Step 5: IC LM358 Comparator

The LM358 is a duel op-amp, meaning there’s two op amps in one IC. One of the simpler circuits and commonly used circuits are the op-amp comparators. A comparator basically compares two voltages and if one is greater than the other the output of the op-amp is either ON or OFF. Comparators have found many uses in Day Night switches, simple Analog to Digital Converters, electronic thermostats and even regulated power supply's.

There are two components we will have to work with in order to determine at what voltage will it switch ON and at what voltage it will switch OFF. Sensing voltage will be the input voltage, this voltage could come off a operational amplifiers output if the real sensors changes are too small to work with. If we have the sensing voltage created via a potentiometer we may ignore using an op-amp to amplify any signal as we will have a reasonable voltage difference to work with. The sensing voltage can be applied to the non-inverting input, this will ensure that once the sensing voltage has exceeded the reserch Reference voltage that must be placed on the inverting input the op-amp will turn ON.

If we apply the sensing voltage to the inverting input and the reference voltage to the non-inverting input we will have the op-amp OFF when the sensing voltage is above the reference voltage and the op amp ON when the sensing voltage is below the reference voltage.

Step 6:

The L298 is an integrated monolithic circuit in a 15- lead Multiwatt and PowerSO20 packages. It is a high voltage, high current dual full-bridge driver designed to accept standard TTL logic levels and drive inductive loads such as relays, solenoids, DC and stepping motors. Two enable inputs are provided to enable or disable the device independently of the input signals.

The emitters of the lower transistors of each bridge are connected together and the corresponding external terminal can be used for the connection of an external sensing resistor. An additional supply input is provided so that the logic works at a lower voltage. L-298 has two enable input to control any device by enabling or disabling it. L 298 IC is most commonly used to make motor drivers or motor controllers. These motor controllers can be controlled by any micro controller e.g Arduino, PIC, Raspberry Pi etc. They receives input from micro controllers and operate the load attached to their output terminals correspondingly.

L-298 motor driver (H-Bridge) is able to control two different DC motors simultaneously. While it can control a single stepper motor as well. L 298 has two Pulse Width Modulation (PWM) pins. PWM pins are used to control the speed of the motor. By changing the voltage signal’s polarity at its input. we can rotate the motor in either clockwise or counter clockwise direction.

Step 7: Rain Sensor

A rain sensor is one kind of switching device which is used to detect the rainfall. It works like a switch and the working principle of this sensor is, whenever there is rain, the switch will be normally closed. The rain sensor module board includes nickel coated lines and it works on the resistance principle. This sensor module permits to gauge moisture through analog output pins & it gives a digital output while moisture threshold surpasses


This circuit has four parts namely Astable Multivibrator, Comparator, Motor Driver and Rain Detector. When water drops of rain falls over the Rain Sensor then it will trigger the PNP transistor BC557 and PNP transistor turns ON the power supply of whole circuit and circuit start working until there is water on the Rain Sensor. Now after the power supply has been turned ON, Astable Multivibrator starts oscillating in configured frequency. Now when the output of 555 Timer IC goes HIGH then the comparator LM358 gives LOW output and when the output of 555 IC goes LOW then the Comparator’s output goes HIGH. And by using these two outputs DC motor turns clock wise and anticlockwise and wiper attached to it turns right to left and left to right, through Motor Driver IC L293D. That is how the wipers automatically sense rain and gets activated. They remain activated until there is water on Rain sensor, as soon as the water evaporates wipers get stopped. Two LEDs are also used here used for indication.


After the sensor detecting the water wiper starts working and sending a visual feedback with red and green led lights.


By this project vehicles can be now available with automatic windscreen wipers that detect the presence of rain and able to clean automatically. Further can be developed such as sensor present automatically adjust the speed and frequency of the blades according to amount of the rain.


It has unique applications in four wheeler, six wheeler, trains, ships, sometimes used for cleaning glass building from outside etc. When comes to advantages low cost and low maintanence , low power consumption.

Step 10: THANK YOU

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