Abstract: A load control device having a power control element connected in series to a series circuit of a load and an alternating power supply and a snubber circuit comprises suppressing means for suppressing current flowing through the snubber circuit when the load is not in operation and for suppressing current flowing through the snubber circuit during a predetermined period which begins when the power control element shifts from an ON state to an OFF state.

Abstract: A load control device having a power control element connected in series to a series circuit of a load and an alternating power supply and a snubber circuit comprises suppressing means for suppressing current flowing through the snubber circuit when the load is not in operation and for suppressing current flowing through the snubber circuit during a predetermined period which begins when the power control element shifts from an ON state to an OFF state.

Abstract: An optocoupler having a driving traic and at least one normally-on driving element couple in series to the driving triac. A light emitting element turns on the driving triac at a time when a phase of a load current is at about 0°. The normally-on driving element is composed of either a MOSFET, or optionally a relay, and an associated element for turning off MOSFET, or relay, at a time when a phase of the load current is about 90°. The arrangement prevents an inrush current or commutation failure, and provides an optocoupler which can be turned off with prescribed timing. Alternative embodiments are disclosed for an optocoupler that can turn itself off when an abnormality occurs, for example, when an ambient temperature rises to an extremely high level.

Abstract: An optically coupled device is composed of input and output sides. The input side includes a light-emitting element while the output side includes: an element for driving; a light-receiving element for receiving light from the light-emitting element to turn on the element for driving; and a resistance element having a positive or negative temperature-coefficient and connected in series with the light-receiving element. By the above configuration, the optically coupled device by itself is constructed to prevent rush-current from occurring and to the device itself from being excessively heated due to excessive current.