17-08-2012, 11:05 AM
AUTOMATIC TEMPERATURE CONTROLLED FAN
ATC FAN.docx (Size: 13.54 KB / Downloads: 146)
ABSTRACT
This project gives an idea about the working of an automatic temperature controlled fan employing thyristor control. Here the speed of a fan can be linearly controlled depending upon the variations in temperature. A thermistor having negative temperature coefficient is employed for temperature sensing. The switching device is a triac (BT136) which is triggered according to the output from the optocoupler. We get a conditioned output through the optocoupler in accordance with the temperature variations of the surroundings. It is accomplished by passing the sensedcurrent through a current voltage converter and a comparator. The reference voltage to the comparator is given through the same supply voltage which is given to the fan after rectifying it by a bridge rectifier.This circuit is highly efficient as it uses thyristor for the power control and we get a linear variation in speed according to the temperature conditions.
ATC FAN.docx (Size: 13.54 KB / Downloads: 146)
ABSTRACT
This project gives an idea about the working of an automatic temperature controlled fan employing thyristor control. Here the speed of a fan can be linearly controlled depending upon the variations in temperature. A thermistor having negative temperature coefficient is employed for temperature sensing. The switching device is a triac (BT136) which is triggered according to the output from the optocoupler. We get a conditioned output through the optocoupler in accordance with the temperature variations of the surroundings. It is accomplished by passing the sensedcurrent through a current voltage converter and a comparator. The reference voltage to the comparator is given through the same supply voltage which is given to the fan after rectifying it by a bridge rectifier.This circuit is highly efficient as it uses thyristor for the power control and we get a linear variation in speed according to the temperature conditions.