Simple Automatic Water Level Controller

by
T.SELVALAKSHMI,
FINAL YEAR ECE
DR.G.U.POPE COLLEGE OF ENGINEERING,
SAWYARPURAM

1. SIMPLE AUTOMATIC WATER LEVEL
CONTROLLER USING
NE 555 IC
A PROJECT REPORT
Submitted by
SELVALAKSHMI.T
The degree of
BACHELOR OF ENGINEERING
IN
ELECTRONICS AND COMMUNICATION
ENGINEERING
DR.G.U.POPE COLLEGE OF ENGINEERING,
SAWYARPURAM


INTRODUCTION

The drinking water crisis in India is reaching alarming proportions. It
might very soon attain the nature of global crisis. Hence, it is of utmost importance

2. to preserve water. In many houses there is unnecessary wastage of water due to
overflow in Overhead tanks. Automatic Water Level Controller can provide a
solution to this problem. The operation of water level controller works upon the fact
that water conducts electricity. So water can be used to open or close a circuit. As
the water level rises or falls, different circuit in the controller send different signals.
These signals are used to switch ON or switch OFF the motor pump as per our
requirements. So, the main objective of this paper is to design and develop an
automatic water level controller to maintain the outlet process of the water level at
its desired level. The paper also focuses on the need of the people to install automatic
water level controller to avoid wastage of water.
The total amount of water available on Earth has been estimated at 1.4
billion cubic kilometres, enough to cover the planet with a layer of about 3 km.
About 95% of the Earth's water is in the oceans, which is unfit for human
consumption. About 4% is locked in the polar ice caps, and the rest l% constitutes
all fresh water found in rivers, streams and lakes which is suitable for our
consumption. A survey estimated that a person in India consumes an average of 135
litres per day. This consumption would rise by 40% by the year 2025. This signifies
the need to preserve our fresh water resources. Automation plays an increasingly
very important role in the world economy and in daily life. Automatic systems are
being preferred over any kind of manual system. People generally worry about the
wastage of water, when they switch ON the motor and forget to OFF them.Our
idea may help them in saving water for future with low cast.
Our project mainly consist of 555timer, 12V motor ,12V relay and wires which
acts as sensor.The wires are placed at the different levels of the tank.All these
mentioned components take an active role in switching ON and OFF of the motor.
BLOCK DIAGRAM

3. CIRCUIT DIAGRAM


COMPONENTS USED IN THE CIRCUIT:
U1
LM555CN
GND
1
DIS
7
OUT
3
RST
4
VCC
8
THR
6
CON
5
TRI
2
VCC
12V
R1
1MΩ
R2
1MΩ
R3
1kΩ
LED1
R4
1MΩ
R5
1MΩ
R6
1MΩ
R7
1MΩ
R8
1MΩ
Q1
BC547A
R9
1kΩ
D1
1N4007
V1
9 V
Water tank
Relay
DC
Motor

4. COMPONENTS SPECIFICATION QUANTITY
Power supply 12V,9V 1,1
IC NE 555 1
Resistor 100 ohm,1K ohm 2,2
LED - 1
BUZZER 12V 1
Relay 12V 1
PCB
-
1
Connecting wires - As required
HARDWARE REQUIREMENTS
1. Power Supply unit
2. NE 555
3. Relay
4. LED/BUZZER
5. DC Motor
POWER SUPPLY BLOCK DIAGRAM
The power supply unit is used to provide a constant 5V of DC supply from a 230V of
AC supply. These 5V DC will acts as power to different standard circuits. It mainly uses
3 devices
1. Bridge wave rectifier
2. Voltage regulator

BRIDGE WAVE RECTIFIER

5. A rectifier is an electrical device that converts alternating current (AC) to direct
current (DC), a process known as rectification. The term rectifier describes a diode that is
being used to convert AC to DC.
VOLTAGE REGULATOR
This is most common voltage regulator that is still used in embedded designs. LM7805
voltage regulator is a linear regulator. With proper heat sink these LM78xx types can
handle even more than 1A current. They also have Thermal overload protection, Short
circuit protection.

Block Diagram of Power Supply
1. In this circuit the 12V adaptor was used as a power supply

The general circuit diagram for total power supply to any embedded device is as shown
below.

6. Circuit Diagram of Power Supply

NE 555 IC:

 In this circuit the NE 555 works as a comparator as well as a controller for
controlling the circuit operation.
 The NE 555 plays a main role in control unit.
 The NE 555 reciveces the signal from the sensor unit and generate the output
signal which was used to control the motor operation.
 If the water level in the tank is LOW then the output of the NE 555 is HIGH,
which switch ON the motor.
 If the water level in the tank is HIGH then the output of the NE 555 is LOW,
which switch OFF the motor.

7. 555 Timer Pin Diagram:

555 Timer Pin Descriptions:
PIN 1: GROUND-All voltages are measured with respect to this terminal.
PIN 2: TRIGGER-The output of the timer depends on the amplitude of the
external triggers pulse applied to the pin.
PIN 3: OUTPUT-There are two ways a load can be connected to the output
terminal either between pin 3and pin 1 ground, or between pin 3 and supply.
PIN 4: RESET-The device 555 is reset by applying a negative pulse to this pin
when the reset function is not in use. The reset terminals should be connected to
Vcc to avoid any possibility of false triggering.
PIN 5: CONTROL VOLTAGE-A external voltage applied to this terminal
changes the threshold as well as the trigger voltage .In other words , by imposing
a voltage on this pin or by connecting a potentiometer between this pin & ground
,the pulse width of the output waveform can be varied.
PIN 6: THRESHOLD-This is the non-inverting terminal of comparator C1,
which monitors the voltage across the external capacitor .when the voltage at the
pin is greater than or equal to2/3 Vcc, the output of comparator C1 goes high,
which in turn switches the output of the low.

8. PIN 7: DISCHARGE-The pin is connected internaly to the collector of the
transistor. Q1 as shown in the internal structure. When the output is high, Q1 is
off and acts as an open circuit to the external capacitor connected between pin 7
& ground. On the other hand, when the output is low, Q1 is saturated and acts as
a short circuit, shorting at the external capacitor C to ground.
PIN 8: VCC-The supply voltage of 5v to 18v is applied to this pin with respect to
ground (pin 1).
Some important features of the 555 timer:
555 timer is used in almost every electronic circuit today. For a 555 timer
working as a flip flop or as a multi-vibrator, it has a particular set of configurations.
Some of the major features of the 555 timer would be,
 It operates from a wide range of power ranging from +5 Volts to +18 Volts
supply voltage.
 Sinking or sourcing 200 mA of load current.
 The external components should be selected properly so that the timing
intervals can be made into several minutes along with the frequencies
exceeding several hundred kilohertz.
 The output of a 555 timer can drive a transistor-transistor logic (TTL) due
to its high current output.
 It has a temperature stability of 50 parts per million (ppm) per degree
Celsius change in temperature which is equivalent to 0.005 %/ °C.
 The duty cycle of the timer is adjustable.
 Also, the maximum power dissipation per package is 600 mW and its
trigger and reset inputs has logic compatibility.

9. INTERNAL STRUCTURE OF NE 555

The timer basically consists of two primary building blocks and they are:
1. Comparators (two) or two op-amp
2. One SR flip-flop (set reset flip-flop)
As shown in the above figure there are only two important components in timer,
they are comparator and flip-flop. Let understand comparators and flip flops.

Comparators:
Comparator is simply a device that compares the voltages at the input terminals
(inverting (- VE) and non-inverting (+VE) terminals). So depending on the
difference in the positive terminal and negative terminal at input port, the output of
the comparator is determined. For example consider positive input terminal voltage
be +5V and negative input terminal voltage be +3V. The difference is, 5-3=+2v.
Since the difference is positive we get the positive peak voltage at the output of the
comparator.

10. Flip-Flop:
The flip-flop is a memory cell, it can store one bit of data. In the figure we can
see the truth table of SR flip-flop.
There are four states to a flip-flop for two inputs; however we need to understand
only two states of the flip- flop for this case.
S R Q Q' (Q bar)
0 1 0 1
1 0 1 0
Now as show in the table, for set and reset inputs we get the respective outputs.
If there is a pulse at the set pin and a low level at reset, then flip-flop stores the value
one and puts high logic at Q terminal. This state continues until the reset pin gets a
pulse while set pin has low logic. This resets the flip-flop so the output Q goes low
and this state continues until the flip-flop is set again.
By this way the flip-flop stores one bit of data. Here another thing is Q and Q bar
are always opposite.
In a timer the comparator and flip-flop are brought together.
Consider 9V is supplied to the timer, because of the voltage divider formed by the
resistor network inside the timer as shown in the block diagram; there will be voltage
at the comparator pins. So because of the voltage divider network we will have +6V
at the negative terminal of the comparator one. And +3V at the positive terminal of
the second comparator.
One another thing is comparator one output is connected to reset pin of flip-flop, so
it the comparator one output goes high from low then the flip-flop will reset. And
on the other hand the second comparator output is connected to set pin of flip-flop,
so if the second comparator output goes high from low the flip-flop sets and stores
ONE.

11. RELAY
A relay is an electrical switch that opens and closes under the control of another
electrical circuit. In the original form, the switch is operated by an electromagnet to
open or close one or many sets of contacts. It was invented by Joseph Henry in 1835.
Because a relay is able to control an output circuit of higher power than the input
circuit, it can be considered to be, in a broad sense, a form of an electrical amplifier.





Relay
Operation
When a current flows through the coil, the resulting magnetic field attracts an
armature that is mechanically linked to a moving contact. The movement either
makes or breaks a connection with a fixed contact. When the current to the coil is
switched off, the armature is returned by a force approximately half as strong as the
magnetic force to its relaxed position. Usually this is a spring, but gravity is also
used commonly in industrial motor starters. Since relays are switches, the
terminology applied to switches is also applied to relays. A relay will switch one or
more poles, each of whose contacts can be thrown by energizing the coil in one of
three ways:

12.  Normally-open (NO) contacts connect the circuit when the relay is activated;
the circuit is disconnected when the relay is inactive. It is also called a Form
A contact or "make" contact.
 Normally-closed (NC) contacts disconnect the circuit when the relay is
activated; the circuit is connected when the relay is inactive. It is also called
a Form B contact or "break" contact.
 Change-over, or double-throw, contacts control two circuits: one normally-
open contact and one normally-closed contact with a common terminal. It is
also called a Form C contact or "transfer" contact. If this type of contact
utilizes “make before break" functionality, then it is called a Form D contact.
The picture shows a working relay with its coil and switch contacts. You can see a
lever on the left being attracted by magnetism when the coil is switched on. This
lever moves the switch contacts





¶
Relay in the circuit

The relay's switch connections are usually labelled COM, NC and NO:
 COM = Common, always connect to this; it is the moving part of the switch.
 NC = Normally Closed, COM is connected to this when the relay coil is off.

13.  NO = Normally Open, COM is connected to this when the relay coil is on.
 Connect to COM and NO if you want the switched circuit to be on when the
relay coil is on.
 Connect to COM and NC if you want the switched circuit to be on when the
relay coil is off.


If your Motor Positive end is connected to NC. When the relay is switched, the
motor will turn OFF. Otherwise it is in ON state. In the COM port we must add the
external power supply to drive the motor. The coil terminals is only for switching
the relay from NC to NO. The relays are of different types here am using 12v DC
SPDT Relay.
LEVEL INDICATOR
 The LED and BUZZER was used as a level indicator.
 When the water is in lower level, it was indicated with the help of LED.
 When the water level is LOW the LED is glow.
 When the water level is goes high, then it was indicated with the help of
BUZZER.
 When the water is level is high then the BUZZER is switched ON.

14. Light Emitting Diode
A light-emitting diode (LED) is a two-lead semiconductor light
source. It is p-n junction diode that emits light when activated. The long
terminal is positive and the short terminal is negative. When a suitable
current is applied to the leads, electrons are able to recombine with
electron holes within the device, releasing energy in the form of
photons. This effect is called electroluminescence, and the color of the
light (corresponding to the energy of the photon) is determined by the
energy band gap of the semiconductor. LEDs are typically small (less
than 1 mm2) and integrated optical components may be used to shape
the radiation pattern.

BUZZER:
A buzzer or beeper is an audio signaling device, which may be mechanical,
electromechanical, or piezoelectric [piezo for short]. Typical uses of buzzers and
beepers include alarm devices, timers, and confirmation of user input such as a
mouse click or keystroke. In this circuit the buzzer was used as a level indicator,
it indicate the high level of the tank.
Specifications:
Piezo Buzzer Round • Black • 12VDC • 12mA • 80dB / 10cm •
Lead wire • 3300Hz • φ24mm x

15. SENSOR UNIT
 In this circuit the connecting wires are used as a sensor, which sense the level
of water in the tank with the help of supply.
 In general the aluminum wire is used.
 The wires are connected on the tank and the power supply is given through
the wire to the water tank.
 The connected wires in LOW and HIGH position conduct the electricity
through water and sent these power to NE 555 for the control of the motor
operation.
ALUMINIUM WIRES (Acts as a sensor):
The Al-steel conductors ACSR (Al Conductor Steel Reinforced) traditionally applied
in overhead lines are characterized by their permissible work temperature at the
level of 80◦C, which equals the existence of limits for the transmission capacity of
the electro energetic networks. A long-term excess of this temperature causes a
risk of irreversible degradation of the strength properties of the Al wires (EN AW
1370), which have both the conductive and carrying function in the lead.

16. Parameters of thermal resistant Al alloy wires:
Wire type AT1 AT2 AT3 AT4
Permissible continuous
work temperature, ◦C
150 150 210 230
Resistivity at 20◦C, nΩm 28.735 31.347 28.735 29.726
Conductivity, % IACS 60 55 60 58
Tensile strength Rm, MPa 159-169 225-248 159-176 159-169

DC Motor:
A DC motor usually means a permanent-magnet, direct-current (DC) motor
of the sort used in toys, models, cordless tools, and robots. These motors are
particularly versatile because both their speed and direction can be readily
controlled; speed by the voltage or duty cycle of their power supply, and direction
by its polarity.


Torque is a measurement of the motors power. The higher the torque of the motor
the more weight it can move. DC motors provide different amounts of torque
depending on their running speed, which is measured in RPM (revolutions per

17. minute). At low RPM DC motors produce poor torque, and generally the higher the
RPM, the better the motors torque. However, in high torque, the speed may be too
high for an application. That's why we have to use gears (or geared motor) to reduce
the overall speed of the motor and running at the top speed to get the most power to,
say, a wheel attached to the shaft of the motor.
TRANSISTOR:
Transistors are the semiconductor device used to amplify and switch
electronic signals and electrical power.
In our project it was used to amplify the signals from the NE 555 IC, which
was suitable for the operation of relay.



WORKING PRINCIPLE
This system mainly works on the principle that “ water conducts electricity” .
We know the property of NE 555 IC , i.e. its output goes HIGH when voltage at the
2
nd
pin (trigger pin) is less than 1/3Vcc .Also we can RESET back the IC by applying
a LOW voltage at the 4
th
pin(RESET pin).Here three wires are dipped in water
tank.Let us define two water levels-Bottom(LOW) level and Top(UP) level ,One of
the wire is from Vcc.The wire from bottom level is connected to the 6
th
pin and the
wire from top level is connected to the 2
nd
pin.

18. When the water level at the tank goes LOW then the pin 6 make connection to
the Vcc, , then the output of the NE 555 IC goes HIGH.Then the base of the transistor
get the supply it applify the signal from the output of NE 555 to suitable for the
operation of 12V relay.It in turn operate the 12V relay then the common terminal of
the make the connection to NO(Normally open) terminal of the relay then the motor
connected between one of coil pin of relay and negative terminal of the battery gets
supply then the motor is switched ON.If the water is in lower level , it was indicated
with the help of LED.When the water level is LOW the LED is glow.
When the water level at the tank goes HIGH then the pin 2 make connection to
the Vcc, then the output of the NE 555 IC goes LOW.Then there is no supply to the
base of the transistor,which in turns connect the common terminal of the relay to the
NC(Normally closed)teminal,then the motor is switched ON.If the water level is
goes high , then it was indicated with the help of BUZZER.When the water is level
is high then the BUZZER is switched ON.
On a final note, the conventional controllers in market mostly use capacitive
sensors and microcontrollers . These increase the cast as well as the complexity of
the system.we have developed a rather simpler but efficient model of a water level
controller.

RESULTS
The automatic water level controller has been successfully designed and
developed.The motor is is turned off and on according to the the water levels.
Compared to other conventional methods, the automatic water level controller
shows excellent performance with its reliable technology and it is cheaper and
durable. The automatic water level controller is a promising controller in terms of
system response in water level control with respect to the non-linearity introduced
by pumps and senson. The experimental model was made according to the circuit

19. diagram and the results were as expected. The motor pump switched ON when the
OHT was about togo dry and switched OFF when the OHT was about to overflow.
CONCLUSION
In these days, when Earth's reserve of consumable water is decreasing
every moment, every drop has its value. Water level controller is simple yet effective
way to prevent wastage of water. Its simplicity in design and low cost components
make it an ideal piece of technology for the common man. Thus the automatic water
level controller is a big boon as concerned with the house hold applications as well
as other water saving purposes including agricultural sector and industries, Based
on the survey results it is found that the automatic water level controller has a rising
demand and it is a good asset from the electronics perspective.
Hence we conclude that-This system is very beneficial in rural as well as urban
areas. It helps in the efficient utilization of available water sources.
If used on a large scale, it can provide a major contribution in the conservation
of water for us and the future generations.

ADVANTAGE & DISADVANTAGES & APPLICATIONS
ADVANTAGES:
1. Automatic water level controller is used to automatically fill the overhead
tank as and when it gets empty and monitor the water level in it.
2. Automatic water level controller is simple and easy to install.
3. Automatic water level controller has low maintenance.
4. Automatic water level controller has compact and elegant design.
5. Automatic water level controller is fully automatic.
6. Automatic water level controller with its precise working saves water and
the motor energy.
7. Automatic water level controller avoids the seepage of walls and roofs
when the tank overflows.

20. 8. Automatic water level controller is ideal as it is difficult to access
overhead tanks.
9. Automatic water level controller has safe operation of motor/pump within
permissible voltage limits.
DISADVANTAGES:
1. It is a passive electrical system and hence it requires continuous power
supply.
APPLICATIONS:
1. It is used for all household purpose.
2. It can be used in commercial centers.
3. It will be very much useful to farmers.
4. It can be used in all places to control water level.

IMPORTANT CONSIDERATION:
The water level controller designed in this project can be used to
control water flow. However, there is no way of knowing whether the source of
water, which in this case is the UGT, actually has water or not. If no water source
is present, then the submersible pump would start running unnecessarily and
overheat itself. This could be taken care by implementing another sensor. Also
the rate of water input must always be equal to or greater than the rate of water
output. To make this happen we could use a speed regulator. If these issues are
taken care of then a more efficient and reliable performance can be achieved.

21. COST ANALYSIS OF PROJECT:
S.NO. COMPONENTS QUANTITY PRICE
(RS.)
1. Power supply 1 130
2. Transistor 1 3
3. Diode 1 3
4. NE 555 IC 1 10
5. Resistor 4 4
6. LED 1 2
7. BUZZER 1 25
8. Relay 1 20
9. Battery 1 18
10. DC Motor 1 30
11. Connecting wires 1 packet 33
12. PCB 1 25
13. Battery clip 1 15
14. Total 13 320

Water pump and its auxiliary components of the system are not consider as
a part of the control unit. Their cost and ratings of the pump vary according to load
connected to the system. An increase in load will lead to selection of a larger pump.
Likewise, the current flowing through the circuit will also increase. Therefore, we
would require a higher rated Relay. For our project we use the 9V DC Motor as a
load, so we use a low rated Relay.