This document describes a fan control circuit that uses a temperature sensor. The circuit uses a thermistor temperature sensor that varies resistance based on temperature to control the speed of a DC fan. As temperature increases, fan speed increases to cool the area. The circuit aims to reduce power consumption by only running the fan as needed based on temperature. It could assist disabled individuals and be used for temperature monitoring and control in various industries.

1. FAN CONTROLLED BY USING TEMPERATURE
SENSOR
BY
B NANDEESH

2. CONTENTS
 Objective of project
 Introduction
 Components used
 Circuit diagram
 Working
 Advantages
 Disadvantages

3. OBJECTIVE OF PROJECT
Our object of making this project is for reducing the power consumption. And
also to assist people who are disabled and are unable to control the speed of
fan.
It may also be used for monitoring changes in environment.
In near future, it can also be used in different industries and electronic devices.

4. INTRODUCTION
 A simple introduction about the temperature controller circuit.
 This circuit project is mainly used for indicating temperature , controlling
temperature.
 The circuit exploits the property of sensor to operate the Fan. A sensor is a
type of transducer
 In a broader sense, a transducer is sometimes defined as any device that
converts energy from one form to another.
 The component that made up the temperature sensor is known as thermistor
 Thermistor is a kind of temperature dependent resistor and its resistance
varies depending on the temperature in its vicinity

5. There are two types of Thermistors
 Negative Temperature Coefficient Thermistor (NTC)
 Positive Temperature Coefficient Thermistor (PTC).
 NTC Thermistor decreases its resistance when the temperature increases

 PTC Thermistor increases its resistance when the temperature increases.
 A small DC fan increases or decreases its speed as per the temperature change.
When the temperature decreases below a certain level, Fan automatically turns off.
 The main principle of this project to monitoring and to control the temperature.


6. COMPONENTS USED:-
 Temperature Sensor
 Resistor
 Capacitor
 DC power supply
 LED
 Diodes
 NPN Transistor
 Motor
 transformer
 Electric Fan 12V
 Vero board
 propeller

7. RESISTOR:-
A resistor is a two-terminal electronic component that produces a voltage
across its terminals that is proportional to the electric current through it in
accordance with Ohm's law:
V = IR
The primary characteristics of a resistor are the resistance, the tolerance,
maximum working voltage and the power rating. Other characteristics
include temperature coefficient, noise, and inductance.

8. CAPACITOR:-
 The capacitor's function is to store electricity, or electrical energy.
 The capacitor is constructed with two electrode plates facing each other, but
separated by an insulator.
 When DC voltage is applied to the capacitor, an electric charge is stored on
each electrode.
 While the capacitor is charging up, current flows.
 The current will stop flowing when the capacitor has fully charged.

9. LED:-
 A light-emitting diode (LED) is an electronic light source.
 LEDs are used as indicator lamps in many kinds of electronics and increasingly
for lighting.
 LEDs are based on the semiconductor diode.
 The longer lead is the Anode side and the short one is the Cathode side.

10. TEMPERATURE SENSOR:-
 The temperature sensor is known as the “Thermistor”
 A thermistor is an electronic component that exhibits a large change in
resistance with a change in its body temperature.
 The word “Thermistor” is actually a contraction of the words “Thermal
Resistor”.

11. DIODE:-
 A diode is a semiconductor device which allows current to flow through it in
only one direction.
 Although a transistor is also a semiconductor device, it does not operate the way
a diode does.
 A diode is specifically made to allow current to flow through it in only one
direction.

12. NTC THERMISTOR
 The NTC thermistors are composed of metal
oxides
 The most commonly used oxides are
those of manganese, nickel, cobalt, iron, copper and titanium.
 A mixture of two or more metal oxide powders are combined with
suitable binders, are formed to a desired geometry, dried and sintered at
an elevated temperature

13. CIRCUIT DIAGRAM

14. BLOCK DAIGRAM
INPUT
(220V AC)
Transforme
r
(220V/12V)
SENSOR
(Themistor)
Rectifier
AC to AC
OUTPUT
(motor
rotating)
Amplifier

15. WORKING
 The main intension is to control the fan by heating the sensor, i.e. the thermistor, where
the speed of the fan is dependent and controlled by any device’s temperature like PC. As
the temperature of the device increases or decreases, the speed of fan increases or
decreases respectively. So it can be used mainly as a cooling device. By modifying the
circuit slightly, it can also be used to control the room temperature, depending on the
property of thermistor.
 The thermistor used in the circuit here, decreases its resistance with increasing
temperature, hence the electrical conductivity also increases, increasing voltage across it,
resulting in an increment in the speed of the fan. Thus, it is possible to control the speed
of the fan automatically when the device’s temperature varies. Experiment can be
followed to evaluate whether this circuit can save energy through the use of temperature
sensor and thus promote efficiency.

16. ADVANTAGES:-
 This project can be used in Home.
 This project can be used in Industry.
 This will help in saving the energy / electricity.
 To monitor the environments that is not comfortable, or possible, for
humans to monitor, especially for extended periods of time.
 Prevents waste of energy when it’s not hot enough for a fan to be
needed.
 To assist people who are disabled to adjust the fan speed
automatically.

17. DISADVANTAGES:-
 It can only be maintained by technical person. Thus, it becomes difficult to be
maintained.
 Due to temperature variation, after sometimes its efficiency may decrease.