The company's high frequency, pulse width modulated (PWM) fans eliminate commutation noise by switching their coils with a PWM frequency above the range of human hearing, i.e., beyond 20 kHz. Fan speed is controlled by an external PWM signal and the
The company's high frequency, pulse width modulated (PWM) fans eliminate commutation noise by switching their coils with a PWM frequency above the range of human hearing, i.e., beyond 20 kHz. Fan speed is controlled by an external PWM signal and the fan speeds up linearly from a 20% duty cycle, up to its maximum rated speed. The fans are available in sizes measuring 70 mm x 15 mm, 70 mm x 25 mm, 80 mm x 25 mm, 92 mm x 25 mm, 120 mm x 25 mm, and 120 mm x 38 mm. Prices range from $4 to $15 each depending on fan size, features, and quantity. JMC PRODUCTS, Austin, TX. (800) 580-6688.
