AUTONATIC_FAN_SPEED_CONTROLLER

Published:2009/7/8 4:54:00 Author:May | From:SeekIC

The controller circuit can reduce a fan's noise, power consumption, and wear, particularly in the presence of a low, fluctuating ambient temperature. Mount a temperature sensor in the fan's airstream, and the circuit will adjust the fan speed as necessary to maintain a relatively constant sensor temperature.Input components R1 and C1 integrate the input square wave, producing a quasitriangular wave at the noninverting input of op amp IC1A. At this inverting input is a reference voltage that decreases as temperature increases. The two-terminal sensor produces 1 μA/°K. The result is a rectangular wave at the output of IC1A with a duty cycle proportional to absolute temperature. Thus, a rise in temperature triggers a counter acting cooling effect by delivering more power to the fan. To calibrate the system with the sensor at room temperature, simply adjust R2 for a 50% duty cycle at V1. The fan will switch off at approximately 0℃ and will be fully on at 44℃.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/AUTONATIC_FAN_SPEED_CONTROLLER.html

Print this Page | Comments | Reading(3)