Abstract: A standard electronics rack-mounted dimming control system includes a chassis having spaces for power modules and a control module which can be inserted into and removed from the chassis without removing the chassis from the rack. Control electronics for generating drive signals for power control devices in the power modules are consolidated in the control module, thereby reducing the per-channel cost of the power modules an protecting the control electronics from heat generating power devices in the power modules. A power module includes an integral chassis and heatsink which forms the top, bottom and side walls of the module. The integral chassis and heatsink includes fins running the length of the module so that cooling air can flow through grooves between the fins when two modules are arranged side by side in the chassis.

Abstract: An optical encoder assembly reduces the space required to mount multiple thumbwheels on a control panel by utilizing wheels with integral encoder patterns. An encoder pattern comprising two tracks of reflective dots is attached to the side of each wheel. Two optical transceivers are mounted on a printed circuit board next to each wheel so that the pattern elements in each of the tracks move past one of the transceivers as the wheels rotate. The transceivers send electrical pulses to a microprocessor each time a dot passes a transceiver. The dots in the two tracks are offset circumferentially to provide a 90 degree phase shift between the tracks as the wheels rotate on a common shaft. The use of dots reduces blurring of the pulse signals. A chassis is mounted to the panel and supports the shaft, the printed circuit board, and a rubber dust shield which rubs against the wheels to provide braking action. The chassis, printed circuit board and dust shield all include slots through which the wheels rotate.