Abstract: A system for detecting the miswiring of an electrical appliance that includes a microprocessor having first and second input connections to sample signals on two different electrical power lines. The microprocessor further includes a third input connection for a neutral line. In an embodiment of the invention, there is at least one switch through which electrical power can flow into a load. The at least one switch is controlled by the microprocessor. In a particular embodiment, the microprocessor is configured to compare the signals sampled at the first and second input connections to determine whether the electrical appliance has been wired correctly.

Abstract: A system for detecting the miswiring of an electrical appliance that includes a microprocessor having first and second input connections to sample signals on two different electrical power lines. The microprocessor further includes a third input connection for a neutral line. In an embodiment of the invention, there is at least one switch through which electrical power can flow into a load. The at least one switch is controlled by the microprocessor. In a particular embodiment, the microprocessor is configured to compare the signals sampled at the first and second input connections to determine whether the electrical appliance has been wired correctly.

Abstract: A defrost heater relay control circuit having reduced power consumption during a de-energized mode of operation is provided. The relay drive circuit utilizes a series connected capacitor to introduce a phase shift in the AC current waveform such that the amount of real power dissipated in the circuit during periods when the defrost heater control relay is de-energized is greatly reduced. This effectively shorts out the relay drive voltage without generating heat due to real power dissipation through the switched circuitry that disables the relay.

Abstract: A driver circuit for a latching type valve is provided which utilizes an electronic switch assembly to provide the dual polarity necessary to actuate the latching type valve to both its open and closed states. The driver circuitry includes a microprocessor and a slope detector circuit for monitoring the coil current used to energize the valve solenoid to determine when the valve armature has moved to its fully actuated position. The driver circuit preferably utilizes power MOSFET devices in the switch assembly configured into an H-bridge to drive the solenoid coil. Advantageously, the user of power MOSFET devices eliminates the necessity for a current sense resistor in the control circuitry, thereby decreasing power dissipation and increasing efficiency of the drive circuit, thereby prolonging the battery life used to drive the valve.

Abstract: A method and apparatus for operating and executing a self-test routine of an LED display device adapted for assembly into home appliance. The device is comprised of a plurality of LED elements, a control processor, a switch assembly, and a signaling element. The self-test routine comprises disposing the switch assembly in a predetermined pattern for detecting switch operability and initiating a program in the processor for self-testing of illumination of the LED elements. The elements are monitored during the self-test routine for communicating a minimum current level preselected as identifying proper illumination. Failure of the self-test routine to properly detect minimum current levels precludes a proper response from the signaling element within a predetermined time limit, thereby causing the display device to be identified as an unacceptable device.

Abstract: A method and apparatus for operating and executing a self-test routine of an LED display device adapted for assembly into home appliance. The device is comprised of a plurality of LED elements, a control processor, a switch assembly, and a signaling element. The self-test routine comprises disposing the switch assembly in a predetermined pattern for detecting switch operability and initiating a program in the processor for self-testing of illumination of the LED elements. The elements are monitored during the self-test routine for communicating a minimum current level preselected as identifying proper illumination. Failure of the self-test routine to properly detect minimum current levels precludes a proper response from the signaling element within a predetermined time limit, thereby causing the display device to be identified as an unacceptable device.

Abstract: A refrigeration control system with self-adjusting defrost interval is provided. The system includes an improved control circuit including an external comparator and a microprocessor having a compressor output drive function and a defrost output drive function. The comparator is linked with the microprocessor with circuit elements for detecting the time period of a defrost operation, comparing the time period with predetermined defrost period limits, generating an output control signal in response to a predetermined relationship between the time period and the limits, and adjusting the defrost interval in response to the control signal whereby the defrost operation is maintained within a preferred preselected time period.