Abstract: The operation of an electromechanical relay is synchronized with the power line waveform where an electrical power supply is supplied from a source to an electrical load. The current voltage supplied to the load is characterized by a power line waveform. An electromechanical relay is positioned between the power supply and the load where contacts of the relay are opened and closed to interrupt and supply power to the load. A microcontroller is positioned between a power source and the electromechanical relay and actuates the relay so that when the contacts are closed or opened the contacts are not exposed to an undesired voltage. A feedback control circuit senses the opening and closure of the contacts so that in the event the contacts, for example close at an undesireable point on the load current waveform the microcontroller adjusts for the necessary delay to cause the actuation of the relay to occur such that the contact closure is at the desired point in the load current waveform.

Abstract: There is provided an efficient circuit which monitors micropressor operation and directs a reset signal to the microprocessor in the event of malfunction. The status monitor circuit operates by maintaining a capacitor charge with a status pulse from the microprocessor. The base of a transistor is controlled by this charged capacitor, such that the transistor switches OFF when the charge is drained and the absence of a status signal is indicated. When the transistor is switched OFF a reset pulse is enabled to the microprocessor. To provide the reset signal, a transformed AC line voltage is applied to the base of a second transistor to switch it ON and OFF in synchronization with the line frequency.

Abstract: The operation of an electromechanical relay is synchronized with the power line waveform where an electrical power supply is supplied from a source to an electrical load. The current voltage supplied to the load is characterized by a power line waveform. An electromechanical relay is positioned between the power supply and the load where contacts of the relay are opened and closed to interrupt and supply power to the load. A microcontroller is positioned between a power source and the electromechanical relay and actuates the relay so that the contacts are closed or opened at a preselected point on the power line waveform. Closure of the contacts at the preselected point is accelerated by supplying an increased power signal to the relay coil and thereafter returning the signal to the rated power.

Abstract: An apparatus for generating a digital pulse train from a dial rotation indicating the direction and degree of rotation. The device incorporates two facing disks mounted to a stem and having mating teeth on adjacent surfaces. One disk is mounted for free rotation about the winding stem and projects an actuating lever arm from its periphery. The other disk is mounted for axial movement and is keyed to rotate with the shaft. Left and right micro-switches are mounted proximate the disks and positioned to be contacted by the actuating lever when it is rotated in the respective left and right directions. During this rotation the stem moves the keyed disk in the selected direction of rotation. The keyed disk engages the free disk and causes it to rotate until the actuating lever arm contacts a micro-switch. When such contact occurs, the free disk is prevented from further rotation and the keyed disk shifts over the teeth of the free disk.

Abstract: Generally there is provided circuitry and a method for frequency multiplication of a first signal source including a first counter for counting pulses from a second signal of higher frequency by counting from a loaded value and generating a circuit output each time the first counter resets. A second counter is used to count cycles of the first counter and generate a feedback signal when a predetermined number of cycles have been completed (the system multiplication factor). Calibration is achieved by comparing the end of the period of the first signal to the occurrence of a feedback signal. In response the comparision circuit causes the loaded value to be changed to thereby control the output.

Abstract: A microcomputer of a household appliance, such as a microwave oven, receives input data from the user for operating the various functions of the appliance. The data is stored in the volatile memory of the microcomputer. The data is compressed into a bit pattern which is representative of all the bits in the volatile memory in the event of a power interruption. The compressed bit pattern is stored in the volatile memory of the microcomputer to be later verified. The operations of the microcomputer is continued for those functions which do not affect volatile memory until the power source is restored or the microcomputer is reset. In either case the volatile memory is verified by generating a compressed bit pattern for current data. The current bit pattern is then compared to an initial bit pattern. If the bit patterns are identical then the volatile memory has not been corrupted by an interruption of power exceeding a preselected "data vaild time".

Abstract: A relay coil associated with a pair of contacts connects an electrical source to a load. Actuation of a coil sensing element by a trigger input signal supplies current to the coil. In response to the trigger input signal the load sensing element supplies a latch maintain signal to a switching element which becomes conductive to establish current flow to the load. As long as the load sensing element detects current to the load the switching element remains conductive for a "latched" state. Interruption of current to the load converts the elements to an "off" state until another trigger input signal is transmitted to the load sensing element.