Abstract: An actuator system has a motor and an output shaft connected to a potentiometer that provides shaft position information. The motor and potentiometer are electrically connected to a common power supply. A microcomputer controls the application of power to the motor and potentiometer so that feedback signals from the potentiometer, indicative of shaft position, can be read when desired without moving the shaft. The motor is prevented from moving either by setting both motor terminals high during a read, or by applying power pulses during a read which are too short in duration to allow the motor to start moving.

Abstract: An ice thickness controller is used to monitor the ice thickness in a refrigeration system. The system has a compressor connected to evaporator tubes which are submerged in a container of water. A DC motor has a shaft extending below the water line in the container. The motor is periodically turned on and a sensing circuit monitors the motor current. If the ice bank in the container is at the correct thickness, the motor shaft will be frozen into the ice. The current draw of the stalled motor will be high with the result that the sensing circuit will turn the compressor off. If the ice bank thickness is low, the motor shaft is free to rotate, so the motor current will be low and the sensing circuit will turn the compressor on.

Abstract: This is concerned with a sensing control for a vacuum cleaner to sense the speed of the beater brush so that when it becomes clogged or jammed and tends to slow down, the control will automatically disconnect all power from the drive motor to thereby protect both the motor and any drive belts that are used. Some aspects are usable with either a canister or an upright vacuum cleaner and some are specifically concerned with an upright unit.