Temperature Controller DC Fan using Thermistor

"Computerization is acceptable, as long as you probably are aware precisely where to put the machine'', In this instructional exercise we are making a Temperature controlled DC fan utilizing Thermistor, as it begins over the preset degree of temperature and stops when the temperature recover to ordinary condition. This entire interaction is done consequently. We have recently made the Temperature controlled Fan utilizing Arduino, where the speed of the fan is additionally controlled consequently.

Circuit diagram of Temperature Controller fan

List of Require Component

• Op amp IC LM741

• NPN Transistor MJE3055

• NTC Thermistor - 10k

• Potentiometer – 10k

• Resistors - 47 Ohm, 4.7k

• DC Fan (Motor)

• Power supply-5v

• Breadboard and connecting wires

Thermistor

The vital segment of this temperature controlled fan circuit is Thermistor, which has been utilized to distinguish the ascent in temperature. Thermistor is temperature delicate resistor, whose opposition changes as indicated by the temperature. There are two sorts of thermistor NTC (Negative Temperature Co-proficient) and PTC (Positive Temperature Co-effective), we are utilizing a NTC type thermistor. NTC thermistor is a resistor whose opposition diminishes as ascend in temperature while in PTC it will build the obstruction as ascend in temperature. We likewise utilized Thermistor in many intriguing applications like Fire alert circuit utilizing Thermistor, Temperature Controlled AC, Thermistor Based Thermostat Circuit.

Op amp IC LM741

An operational Amplifier is a DC-coupled high addition electronic voltage intensifier. It's a little chip having 8 pins. An operational enhancer IC is utilized as a comparator which thinks about the two sign, the upsetting and non-rearranging signal. In Op-amp IC 741 PIN2 is a transforming input terminal and PIN3 is non-altering input terminal. The yield pin of this IC is PIN6. The fundamental capacity of this IC is to do numerical activity in different circuits.

Operation amp fundamentally has Voltage Comparator inside, which has two information sources, one is rearranging information and second is non-upsetting information. At the point when voltage at non-rearranging input (+) is higher than the voltage at altering input (- ), at that point the yield of comparator is High. Furthermore, if the voltage of altering input (- ) is Higher than non-modifying end (+), at that point output is LOW. Operation amps have enormous addition and generally utilized as Voltage Amplifier. Some Op-amps have more than one comparator inside (operation amp LM358 has two, LM324 has four) and some have only one comparator like LM741.The utilization of this IC predominantly incorporates a viper, subtractor, voltage adherent, integrator and differentiator. The output of the operational intensifier is the result of the addition and the info voltage. Check here for other Op-amp Circuits.

It deals with the rule of thermistor. In this circuit, PIN 3 (non-rearranging terminal of operation amp 741) is associated with the potentiometer and PIN 2 (altering terminal) is associated in the middle of R2 and RT1 (thermistor) which is making a voltage divider circuit. At first, in the ordinary condition the yield of the operation amp is LOW as the voltage at non-reversing input is lesser than rearranging input which makes the NPN semiconductor stays in off condition. The semiconductor stays in OFF condition on the grounds that there is no voltage applied to its base and we need some voltage at its base to make the NPN semiconductor lead. Here we have utilized NPN semiconductor MJE3055 yet any high current semiconductor can work here like BD140.

Non when the temperature is expanded, the opposition of Thermistor perishes and the voltage at non-upsetting terminal of operation amp gets higher than the reversing terminal, so the operation amp yield PIN 6 will turn out to be HIGH and semiconductor will be (on the grounds that when the yield of operation amp is HIGH the voltage will move through the authority to producer). Presently this conduction of NPN semiconductor permits the Fan to begin. As the thermistor get back to the typical condition the fan will naturally kill.

Advantages

Easy to handle and economical

Fan starts automatically, so it can control the temperature manually.

Automatic switching will save the energy.

For cooling heat dissipating devices, installation is easy.

Applications of Temperature Controlled DC Fan

Cooling fans for laptops and computers.

This device is used for cooling the car engine.