A thermal control variable speed DC brushless fan, especially a DC brushless fan which may change speed in accordance with the temperature sensed, includes a fan speed control circuit and a DC brushless fan. The fan speed control circuit is composed of drive ICs, operation amplifiers, transistors, diodes,...http://www.google.com/patents/US5197858?utm_source=gb-gplus-sharePatent US5197858 - Thermal control variable speed DC brushless fan
