Claims
- 1. A method for dispersing beat frequencies in a multiple fan system, comprising:providing at least two fans, each fan being operable as a constant speed fan or as an oscillating speed fan; operating only one of the fans as a constant speed fan, each other fan being operated as an oscillating speed fan; operating each of the oscillating speed fans using a means for controlling a plurality of fans, the means for controlling operating each oscillating speed fan within a different range of speed from each other oscillating speed fan; and using the means for controlling for providing an output voltage having a varying duty cycle and providing an oscillating fan speed profile having an oscillating speed range.
- 2. the method as defined in claim 1 further comprising:including, in the fan controller, a waveform generating portion coupled to a duty-cycle modulator portion.
- 3. The method as defined in claim 1 wherein each of the fans is electrically operated by a DC voltage and the controlling means varies the DC voltage.
- 4. The method as defined in claim 1 wherein each of the fans is electrically operated by a DC voltage and the controlling means utilizes a continuously varying duty cycle for varying the DC voltage.
- 5. The method as defined in claim 1 wherein each of the fans is electronically operated by a DC voltage and the controlling means includes a waveform generator and a duty-cycle modulator for varying the DC voltage.
Parent Case Info
This application is a divisional application of U.S. Ser. No. 09/245,145 filed Feb. 4, 1999.
US Referenced Citations (18)