Automatic Fan Controller Circuit Diagram using Temperature Sensor.

Automatic Fan Controller Circuit Diagram using Temperature Sensor.

In this project, I will design a practical temperature controller that controls the temperature of any device according to its requirement for any industrial application. It can monitor the temperature and displays it on an LCD display in the range of –50°C to +150°C. The heart of the circuit is an Arduino board which controls all its functions. A NTC (Negative Temperature Coefficient) Thermistor is used as temperature sensor.

There are many potential applications for NTC thermistors. Their accuracy and stability make them highly useful for a wide range of purposes. These applications include temperature measurement, compensation, and control. Over the last decade, advances in electronics have made devices smaller, cheaper and faster. This project is about how the speed of a fan can be controlled, based on a temperature sensor. It is also a part of smart home application where the fan will gradually increase its speed if the temperature is increasing. In general, home appliance fans need to be operated manually with the help of regulators with the variation of temperature, thus requiring a repeatedly extra effort for regulating the fan speed which acts to our agony. So as to reduce this extra effort and to add comfort, it is intended in this paper designing an “Automatic Temperature Controlled Fan”.

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 the 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, its resistance decreases with increasing temperature, hence the electrical conductivity also increases, increasing voltage across it, resulting in an increase 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.

The circuit exploits the property of sensor to operate the DC 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. Besides that, the component that made up the temperature sensor is known as the thermistor. Thermistor is a kind of temperature dependent resistor and its resistance varies depending on the temperature in its vicinity. There are two types of Thermistors- Negative Temperature Coefficient Thermistor (NTC) and Positive Temperature Coefficient Thermistor (PTC). Thermistors are an analog temperature device is interfaced to the analog pin of the Arduino board, through its built-in ADC, which converts this analog reading and displays that on the LCD, to indicate the temperature of the device. User-defined temperature settings can be done using push buttons provided through Arduino board. Maximum and minimum settings are used to allow any necessary hysteresis. Few push buttons are used to set the temperature by INC, to increase and DEC to decrease settings. As soon the max and min temperatures are set then the Arduino program generates PWM output on the corresponding digital output according to the measured temperature. This is fed to a DC Fan through a motor driver IC. The fan speed is proportional to the measured temperature.

The resistance of most common types of thermistor decreases as the temperature rises. They are called negative temperature coefficient, or NTC, thermistors. Note the -t° next to the circuit symbol. A typical NTC thermistor is made using semiconductor metal oxide materials. (Semiconductors have resistance properties midway between those of conductors and insulators.) As the temperature rises, more charge carriers become available and the resistance falls. Its simple circuit using the principle of the voltage divider rule to calculate the output voltage which eventually leads to measuring the temperature difference.

We can module the thermistor sensor as follow:

1. A model for the resistivity of a semiconductor as a function of the temperature was found by Steinhart and Hart 1968. A common method to characterize a thermistor is to use the Steinhart-Hart equation:

1/T = A + [B * ln(R)] + [C * ln(R)^3]

The Steinhart-Hart law describes the absolute temperature T (in Kelvins) as a function of the NTC thermistor's resistivity (in Ω) according to the formula above.

 

Automatic Fan Controller Circuit Diagram using Temperature Sensor.

In this project, I will design a practical temperature controller that controls the temperature of any device according to its requirement for any industrial application. It can monitor the temperature and displays it on an LCD display in the range of –50°C to +150°C. The heart of the circuit is an Arduino board which controls all its functions. A NTC (Negative Temperature Coefficient) Thermistor is used as temperature sensor.

There are many potential applications for NTC thermistors. Their accuracy and stability make them highly useful for a wide range of purposes. These applications include temperature measurement, compensation, and control. Over the last decade, advances in electronics have made devices smaller, cheaper and faster. This project is about how the speed of a fan can be controlled, based on a temperature sensor. It is also a part of smart home application where the fan will gradually increase its speed if the temperature is increasing. In general, home appliance fans need to be operated manually with the help of regulators with the variation of temperature, thus requiring a repeatedly extra effort for regulating the fan speed which acts to our agony. So as to reduce this extra effort and to add comfort, it is intended in this paper designing an “Automatic Temperature Controlled Fan”.

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 the 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, its resistance decreases with increasing temperature, hence the electrical conductivity also increases, increasing voltage across it, resulting in an increase 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.

The circuit exploits the property of sensor to operate the DC 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. Besides that, the component that made up the temperature sensor is known as the thermistor. Thermistor is a kind of temperature dependent resistor and its resistance varies depending on the temperature in its vicinity. There are two types of Thermistors- Negative Temperature Coefficient Thermistor (NTC) and Positive Temperature Coefficient Thermistor (PTC). Thermistors are an analog temperature device is interfaced to the analog pin of the Arduino board, through its built-in ADC, which converts this analog reading and displays that on the LCD, to indicate the temperature of the device. User-defined temperature settings can be done using push buttons provided through Arduino board. Maximum and minimum settings are used to allow any necessary hysteresis. Few push buttons are used to set the temperature by INC, to increase and DEC to decrease settings. As soon the max and min temperatures are set then the Arduino program generates PWM output on the corresponding digital output according to the measured temperature. This is fed to a DC Fan through a motor driver IC. The fan speed is proportional to the measured temperature.

The resistance of most common types of thermistor decreases as the temperature rises. They are called negative temperature coefficient, or NTC, thermistors. Note the -t° next to the circuit symbol. A typical NTC thermistor is made using semiconductor metal oxide materials. (Semiconductors have resistance properties midway between those of conductors and insulators.) As the temperature rises, more charge carriers become available and the resistance falls. Its simple circuit using the principle of the voltage divider rule to calculate the output voltage which eventually leads to measuring the temperature difference.

We can module the thermistor sensor as follow:

1. A model for the resistivity of a semiconductor as a function of the temperature was found by Steinhart and Hart 1968. A common method to characterize a thermistor is to use the Steinhart-Hart equation:

1/T = A + [B * ln(R)] + [C * ln(R)^3]

The Steinhart-Hart law describes the absolute temperature T (in Kelvins) as a function of the NTC thermistor's resistivity (in Ω) according to the formula above.