Rain Alarm Project is a simple but very useful project that detects Rain (Rain Water) and automatically triggers an alarm or buzzer. Water is a basic need in every one’s life. Saving water and proper usage of water is very important. Here is an easy project which will give the alarm when there is rain, so that we can make some actions for rain water harvesting and also save the rain water for using it later. With the help of saving this rain water through rain water harvesting, we can increase the levels of underground water by using underwater recharge technique. Rain water detector will detect the rain and make an alert; rain water detector is used in the irrigation field, home automation, communication, automobiles etc. Here is the simple and reliable circuit of rain water detector which can be constructed at low cost.

1. PONDICHERRY UNIVERSITY
( Pondicherry University,Chinna Kalapet,Kalapet,Puducherry-605014)
A PROJECT REPORT
ON
“AUTOMATIC RAIN ALARM SENSOR/ CONTINUITY TESTER”
Submitted in the partial fulfilment of the requirement for the Award of Degree of
M-TECH ELECTRONICS AND COMMUNICATION ENGINEERING
SUBMITTED BY
FAIZAN SHAFI [21304012]
Under the Guidance of
Dr. K.ANUSUDHA
Assistant professor
DEPARTMENT OF ELECTRONICS ENGINEERING
SCHOOL OF ENGINEERING AND TECHNOLOGY
PONDICHERRY UNIVERSITY, KALAPET,
PUDUCHERRY-605014

2. Abstract
Rain Alarm Project is a simple but very useful project that detects Rain (Rain Water) and
automatically triggers an alarm or buzzer. Water is a basic need in every one’s life. Saving water
and proper usage of water is very important. Here is an easy project which will give the alarm
when there is rain, so that we can make some actions for rain water harvesting and also save the
rain water for using it later. With the help of saving this rain water through rain water harvesting,
we can increase the levels of underground water by using underwater recharge technique. Rain
water detector will detect the rain and make an alert; rain water detector is used in the
irrigation field, home automation, communication, automobiles etc. Here is the simple and
reliable circuit of rain water detector which can be constructed at low cost.

3. Contents
1. INTRODUCTION 1
2. CIRCUIT DESCRIPTION 2
1. BLOCK DIAGRAM
2. CIRCUIT DIAGRAM
3. COMPONENT DESCRIPTION
2
3
5
1. RESISTOR
2. CAPACITOR
3. TRANSISTOR
4. BUZZER
3.5 555 IC
3.6
5
6
7
8
9
Sensor
Rain
11
4. ADVANTAGES AND DISADVANTAGES 12
5. PCB MAKING PROCESS 14
6. CONCLUSION AND FUTURE SCOPE 16
REFERENCES 17

4. List of Figures
1. Block Diagram
2. Circuit Diagram
3. Resistor
4. Capacitor
5. Transistor
6. Buzzer
7. 555 Timer IC
8. Rain sensor
6.1 PCB Layout
2
3
5
6
7
8
10
11
15

5. Chapter 1
INTRODUCTION
Mankind has always harnessed the elements of nature for different purposes. Water for irrigation
and Electricity generation (Hydro Electric Power), wind for wind mill used for many
applications ranging from turning turbines that generate electricity, to quarry for crushing stones,
sun for drying, heating and cooking especially when brought to focus. From time immemorial
humans used the sun to dry many things, a process known as sun drying. Sun drying is carried
out in the farm, home, industry, laboratory, hospitals and other institution for a number of
reasons. These reasons range from totally driving out water molecules from the things being
dried, outright drying, like clothes, some farm produce, during building work, and in sculpture to
exposing certain electronic materials/components directly to the sun so that the ultra- violet
rays from the sun can cause some changes in the component, and in
pharmaceutical/chemical industries where certain plants used for pharmaceutical
purpose/chemicals are exposed to direct sunlight for a little while to cause some chemical
changes in them and even at home sometimes when we open our windows to allow the sun
rays to fall into our rooms to eliminate dampness, and allows for proper aeration. When rain
falls, it will cause a setback to all the reasons for sun- drying enumerated above, especially
when the materials being sun dried are not retrieved quickly. Thus, designing and
constructing a device which gives one a heads-up the instant it starts to rain hopefully
giving you time to retrieve the materials being sun dried, close your windows, and bring in
possession is not only apropos but also absolutely imperative. Also, since it can rain at any
time without any warning clothes in a clothes line outside the house that are almost dry may
get wet if we do not realize it is raining on time.
1

6. Chapter 2
CIRCUIT DISCRIPTION
It is a Automatic Rain Sensing Alarm circuit. In this circuit we use IC 555timer, 5 resistors, 1
capacitor, 1 NPN BC545 transistor, 1 buzzer, 9v battery and rain sensor which is connected to
point A and B as shown in fig (2)
2.1 BLOCK DIAGRAM
Fig 2.1: Block Diagram
Rain water sensor is the main component in the circuit. For this rain sensor, no need to go and
buy in the market or online. We can do it ourselves just by taking the piece of Bakelite or mica
board and aluminum wire. Bakelite or mica board should be made completely flat and
aluminum wire should be pasted on the flat board as shown in the figure below of rain water
sensor. Care should be taken that there should be no spaces between the wire and board. When
the rain water sensor is completed, it should get connected to the circuit and voltage should be
passed through the wires. If there is no rain, the resistance between the wires will be very high
and there will be no conduction between the wires in the sensor. If there is rain, the water
drops will fall on the rain sensor which will also decrease the resistance between the wires
and wires on the sensor board will conduct andtrigger the NE555 timer through the transistors
circuitry. Once NE555 is triggered,it will make the output pin high and which will make the
buzzer to make alarm.
2

7. 2.2 CIRCUIT DIAGRAM
Fig 2.2: Circuit Diagram
3

8. 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 dropsfalls 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
(initiallyit 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. Here we can see that 555 Timer IC has been
configured in Astable modeso that Buzzer generate a oscillating sound (means periodically on
and off). This oscillation frequency can be controlled by changing the value of resistor R2
and/orcapacitor C1. Pin 5 control Pin, should be connected to ground through a .01uf
capacitor. Resistor R3 and R4 has been used to control the transistors collectorand base current
respectively. Rain sensor should be kept at 30-40 degree from the ground, so that water cannot
stay on it, for the long time, this will prevent the alarm to going on for a long time.
4

9. Chapter 3
Component Description
3.1 RESISTOR:
A resistor is a passive two-terminal electrical component that implements elec-trical resistance
as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust
signal levels, to divide voltages, bias active elements,and terminate transmission lines, among
other uses. High-power resistors that can dissipate many watts of electrical power as heat may
be used as part of motorcontrols, in power distribution systems, or as test loads for generators.
Fixed resis-tors have resistances that only change slightly with temperature, time or
operatingvoltage. Variable resistors can be used to adjust circuit elements (such as a
volumecontrol or a lamp dimmer), or as sensing devices for heat, light, humidity, force,or
chemical activity. Resistors used are 4.7k, 470E, 1k,
Fig 3.1: Resistor
5

10. 3.2 CAPACITOR
A capacitor is a passive two-terminal electrical component that stores electricalenergy in an
electric field. The effect of a capacitor is known as capacitance. Whilecapacitance exists
between any two electrical conductors of a circuit in sufficientlyclose proximity, a capacitor is
specifically designed to provide and enhance thiseffect for a variety of practical applications by
consideration of size, shape, andpositioning of closely spaced conductors, and the
intervening dielectric material.A capacitor was therefore historically first known as an electric
condenser.
Fig 3.2: Capacitor
6

11. 3.3 TRANSISTOR
A transistor is a semiconductor device used to amplify or switch electronic signalsand electrical
power. It is composed of semiconductor material usually with atleast three terminals for
connection to an external circuit. A voltage or currentapplied to one pair of the transistor’s
terminals controls the current through an-other pair of terminals. Because the controlled
(output) power can be higher than the controlling (input) power, a transistor can amplify a signal.
Fig 3.3: Transistor
7

12. 3.4 BUZZER
A buzzer or beeper is an audio signaling device, which may be mechanical, elec-tromechanical,
or piezoelectric. Typical uses of buzzers and beepers include alarmdevices, timers, and
confirmation of user input such as a mouse click or keystroke.
Types of buzzer:
Electromechanical: Early devices were based on an electromechanical systemidentical to an
electric bell without the metal gong. Similarly, a relay may beconnected to interrupt its own
actuating current, causing the contacts to buzz.Often these units were anchored to a wall
or ceiling to use it as a sounding board.The word ”buzzer” comes from the rasping noise
that electromechanical buzzersmade.
Mechanical: A joy buzzer is an example of a purely mechanical buzzer. They require drivers.
Piezoelectric: A piezoelectric element may be driven by an oscillating electroniccircuit or
other audio signal source, driven with a piezoelectric audio amplifier.Sounds commonly used to
indicate that a button has been pressed are a click, aring or a beep. Battery 9v: An electric battery
is a device consisting of one or moreelectrochemical cells with external connections provided
to power electrical devicessuch as flashlights, smartphones, and electric cars. When a battery
is supplyingelectric power, its positive terminal is the cathode and its negative terminal isthe
anode. The terminal marked negative is the source of electrons that whenconnected to an
external circuit will flow and deliver energy to an external device.When a battery is
connected to an external circuit, electrolytes are able to moveas ions within, allowing the
chemical reactions to be completed at the separateterminals and so deliver energy to the
external circuit. It is the movement of thoseions within the battery which allows current to
flow out of the battery to performwork. Historically the term ”battery” specifically
referred to a device composedof multiple cells, however the usage has evolved
additionally to include devicescomposed of a single cell.
Fig 3.4: Buzzer
8

13. 3.5: 555 TIMER IC:
9
PIN NAME PURPOSE
1 GND Ground reference voltage, low level (0 V)
2 TRIG The OUT pin goes high and a timing
interval starts when this input falls below 1/2 of
CTRL voltage (which is typically 1/3 Vcc, CTRL
being 2/3 Vcc by default if CTRL is left open). In
other words, OUT is high as long as the trigger
low. Output of the timer totally depends upon the
amplitude of the external trigger voltage applied
to this pin.
3 OUT This output is driven to approximately 1.7 V
below +Vcc, or to GND.
4 RESET A timing interval may be reset by driving this
input to GND, but the timing does not begin again
until RESET rises above approximately 0.7 volts.
Overrides TRIG which overrides threshold.
5 CTRL Provides “control” access to the internal voltage
divider (by default, 2/3 Vcc).
6 THR The timing (OUT high) interval ends when the
voltage at threshold is greater than that at CTRL
(2/3 Vcc if CTRL is open).
7 DIS Open collector output which may discharge a
capacitor between intervals. In phase with output.
8 Vcc Positive supply voltage, which is usually between
3 and 15 V depending on the variation.

14. Fig 3.5: 555 Timer IC
10

15. 3.6 RAIN SENSOR:
A rain sensor or rain switch is a switching device activated by rainfall. There are two main
applications for rain sensors. The first is a water conservation device connected to an automatic
irrigation system that causes the system to shut down in the event of rainfall. The second is a
device used to protect the interior of an automobile from rain and to support the automatic
mode of windscreen wipers. An additional application in professional satellite
communications antennas is to trigger a rain blower on the aperture of the antenna feed, to
remove water droplets from the mylar cover that keeps pressurized and dry air inside the wave-
guides. Rain sensors for irrigation systems are available in both wireless and hard-wired
versions, most employing hygroscopic disks that swell in the presence of rain ands shrink back
down again as they dry out an electrical switch is in turn depressed or released by the
hygroscopic disk stack, and the rate of drying is typically adjusted by controlling the
ventilation reaching the stack. However, some electrical type sensors are also marketed that
use tipping bucket or conductance type probes to measure rainfall. Wireless and wired
versions both use similar mechanisms to temporarily suspend watering by the irrigation
controller specifically they are connected to the irrigation controller’s sensor terminals, or
are installed in series with the solenoid valve common circuit such that they prevent the
opening of any valves when rain has been sensed.
11

16. Fig 3.6: Rain Sensor
Chapter 4
Advantages and Disadvantages
ADVANTAGES:
1.Conserve Water: There is a lot of water that you can save by using a rain sensor. By
automatically turning off your lawn irrigation system every time it rains, the conserved water
can be used in other essential purposes such as fighting fire.
2.Prevent Disease Damage and Nutrient: Loss Over-watering prevent the roots of your plants
from reaching deep into the ground making your plants vulnerable to disease. Over-watering is
also one of the major causes of nutrient loss in plants as excessive watering washes away the
nutrients of the soil leaving your plants weak and unhealthy.
3.Save Money on Fertilizer: A rain sensor prevents you from overwatering your plants and
lawn. When a plant is overwatered, the nutrients from the turf wash away into the drainage
system. You have to compensate by adding more fertilizers to your lawn and plants. This means
spending more money on fertilizers. With a rain sensor that effectively prevents your lawn
irrigation system from over watering your lawn and plants, your garden turf will remain to be an
ideal environment for your plants in accordance with the fertilizer that you are using.
4.Increase the Life-span of your Irrigation System Using a rain sensor prevents unnecessary
wear and tear of your lawn irrigation system since it minimizes the amount of time that your
lawn irrigation is in operation. This is especially useful during the rainy season where rain
unpredictably come and go.
5.Prevent Groundwater and Waterways Pollution A lawn irrigation system equipped with a
rain sensor minimizes wasteful run off such as pesticides, motor oil, fertilizer, pet waste and
sediments from reaching your waterways. It also minimizes garden pollutants such as herbicides
and fertilizers from getting into your groundwater system.
12

17. DISADVANTAGES:
1. It doesn’t tell about the speed of the rain which is fallen on the roof.
2. It will send signal or the led will be glowing until the detector becomes wet.
3. It something is over that then the detector will not work until it gets wet.
4. There are so many problems that you will face when you will make this circuit.
13

18. Chapter 5
PCB MAKING PROCESS
1. While designing a layout, it must be noted that the size of board should be as small as
possible
2. Before starting, all components should be placed properly so that an accurate
measurement of space can be made.
3. The component should not be mounted very close to each other or far away from one
another.
4. The layout is first printed on tracing paper then traced on copper plate.
5. The copper plate is first dip in photo resistive solution.
6. Then it is heated and dry.
7. Then placing print on copper plate and that plate on ultra light exposure box for 15 min.
8. Then plate is dipped in thinner where the tracks get visible.
9. Then this plate is kept in etching solution for 15 min.
10. Then drilling is done according to the components.
14

19. Fig 6.1: PCB Layout
15

20. Chapter 6
CONCLUSION AND FUTURESCOPE
CONCLUSION
The rain water detector-alarm system will be useful in both domestic and industrial applications.
It alerts the users of the presence of rain when it is just about to rain as even the minutest
droplets of water triggers it ON thereby giving the user ample time to retrieve possessions, shut
windows, and in some cases prepare to harvest rain water. The device when properly placed to
receive the first set of droplets of rain water can save the user from damaging possessions that
were being sundried/prevent rain from entering homes, offices, and silos etc.
FUTURE SCOPE
Using more appropriate rain sensor we can make precise automatic rain sensing system by
adding microcontroller-based system we can implement some security features for farmer.
16

21. REFRENCES
1. https://circuitdigest.com
2. https://components101.com
3. Embeddronics.http//www.embeddronics.com
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