Abstract: A fiber optic frost sensor for use in a refrigerating apparatus having evaporator coils is used to determine when ice or frost has accumulated on the evaporator coils to an extent that the air around the evaporator coils cannot be cooled efficiently. The frost sensor includes a fiber optic cable located adjacent to the evaporator coils, the fiber optic cable extending between a light transmitter and a light receiver. As ice and frost accumulate on the evaporator coils, the ice and frost also accumulate on the outer surface of the fiber optic cable resulting in a change in the amount of light traveling from the transmitter to the receiver through the fiber optic cable. When the amount of light received by the receiver changes a preselected amount, the receiver determines that a defrost cycle needs to be initiated to melt the accumulated ice or frost. In one embodiment, a serpentine fiber optic cable is looped along the evaporator coils.

Abstract: A control circuit for dispensing detergent and a wetting agent in a dishwasher is provided in which a single triac can be utilized to selectively energize either the detergent dispenser operator or the wetting agent dispenser operator by connecting the two operators, each in series with an oppositely oriented diode, in parallel, and such connection in series with the triac, and then biasing the triac into low impedance at the beginning of either positive or negative half line cycle depending on the operator selected to be energized. If an operator is of low resistance, it is connected in series with the heater which then acts as a current limiter, and if the operator is of high impedance, it is connected in parallel with the heater.

Abstract: A fiber optic door ajar sensor for a domestic appliance such as a refrigerator/freezer having refrigerator compartment and freezer compartment doors includes a light transmitter and a light receiver. In one embodiment, a U-shaped loop of fiber optic cable is positioned relative to the transmitter and the receiver so that changes in the amount of light transmitted from the transmitter via the fiber optic cable to the receiver enables the receiver to determine whether one of the doors is open or slightly ajar. Another embodiment of the door ajar sensor includes a fiber optic cable having one end adjacent to one of the doors and a distal or transmitting end adjacent to a light receiver. When the door is opened or left ajar, ambient light is transmitted via the fiber optic cable to the receiver. The receiver responds to a preselected amount of light received via the fiber optic cable by providing a door open indication.