Controlled switching circuit

A switching circuit for controlling a plurality of external load circuits under direction of a control arrangement electrically isolated from at least one of said external load circuits, said control arrangement being capable of operating with electrical energy received from a source thereof in one of said external load circuits, said switching circuit comprising:

• a first switching means having first and second switching terminals, a supply terminating region, and a control region by which said switching means is capable of being directed, through electrical energization thereof, to effectively provide a conductive path of a selected conductivity between said first switching means first and second switching terminals and between said first switching means first switching terminal and its supply terminating region, said first switching means first and second switching terminals being adapted for electrical connection to a selected one of said plurality of external load circuits;
• a second switching means having first and second switching terminals and a control region by which said switching means is capable of being directed, through being irradiated by electromagnetic radiation, to effectively provide a conductive path of a selected conductivity between said second switching means first and second switching terminals, said second switching means first and second switching terminals being adapted for electrical connection to a selected one of said plurality of said external load circuits;
• a controlled radiation source means having first and second energization regions between which a radiation emitting device is electrically connected, said radiation emitting device being capable of emitting electromagnetic radiation for sufficient current passing therethrough drawn from that current, if any, flowing between said controlled radiation source means first and second energization regions, said radiation emitting device being positioned to irradiate said second switching means control region, said controlled radiation source means first energization region being electrically connected to said first switching means first switching terminal;
• and
• a controller having first and second energizing regions and first and second output regions, said controller being capable, if electrically energized at its energizing regions, of selectively being directed to effectively provide a conductive path of a selected conductivity between said controller first and second output regions, said controller first energizing region being electrically connected to said controlled radiation source means second energization region and to said first switching means supply terminating region, said controller second energizing region being electrically connected to said first switching means second switching terminal, said controller first output region being electrically connected to said first switching means control region, and said controller second output region being electrically connected to said first switching means second switching terminal.