Abstract: A fan trays assembly is made of one or small number of cast or injection molded (collectively “cast”) components. Each component can be cast of plastic, metal or another material. One of the components of the fan tray includes a front wall, a back wall, two side walls, an inner wall defining a Venturi and a motor housing suspended within the Venturi by one or more structural members. The walls, the motor housing and the structural member(s) are all formed as a single casting. Casting these pieces together reduces the complexity and cost of manufacturing the fan trays. Multi-fan fan trays and modular fan trays can be similarly made.

Abstract: A method and apparatus for controlling the speed of a DC electric motor receives a periodic commutation signal having a fixed duration on cycle and an off cycle. The commutation signal then is modified to form a periodic modified commutation signal having substantially the same period duration as the commutation signal. The modified commutation signal has a single on cycle per period. The method and apparatus then determine a desired speed of the motor, and vary the duration of the on cycle of the commutation signal to form the on cycle of the modified commutation signal. The on cycle of the modified commutation signal has a duration that is less than the fixed duration. By varying in this manner, the rotor rotates at substantially the desired speed.

Abstract: A method and apparatus for controlling the speed of a DC electric motor receives a periodic commutation signal having a fixed duration on cycle and an off cycle. The commutation signal then is modified to form a periodic modified commutation signal having substantially the same period duration as the commutation signal. The modified commutation signal has a single on cycle per period. The method and apparatus then determine a desired speed of the motor, and vary the duration of the on cycle of the commutation signal to form the on cycle of the modified commutation signal. The on cycle of the modified commutation signal has a duration that is less than the fixed duration. By varying in this manner, the rotor rotates at substantially the desired speed.