Power-up circuit for microprocessor based appliance control

Abstract

A power-up circuit is provided for a microprocessor based appliance control which includes a power source providing power between first and second conductors. A first circuit is connected across the conductors and a second circuit is electrically disconnected from one of the conductors and from the power source by a normally open switch. The second circuit includes a microprocessor control and the first circuit includes a relay coil for controlling the normally open switch. An optically coupled solid state relay couples the first and second circuits through a pair of light actuated silicon controlled rectifiers in the first circuit for energizing the relay coil and a pair of light emitting diodes in the second circuit for illuminating the light actuated silicon controlled rectifiers. A touch switch and related components are associated with the first circuit and are responsive to manual actuation of the touch switch to initiate energization of the relay coil independent of the light emitting diodes to effect closing of the normally open switch and connection of the second circuit to the power source. After this connection, the light emitting diodes will emit light to illuminate the silicon controlled rectifiers and maintain the relay coil in an energized posture until the cycle is terminated through the microprocessor control.