Abstract: A power switching circuit selectively connects an electrical load having first and second input connections to any one of a plurality of branch power circuits. Each branch circuit includes a first and second conductor defining a relative voltage therebetween. The power switching circuit includes a selector switch for selecting which of the branch circuits is to be connected to the load. A triac is electrically connected to the first conductor of each branch circuit and to the first input connection of the load for selectively electrically connecting one of the first conductors to the first input connection. A triac is electrically connected to the second conductor of each branch circuit and to the second input connection of the load for selectively electrically connecting one of the second conductors to the second input connection.

Abstract: A circuit of a detection switch for generating an output signal for driving a load device in accordance with the detection result by a detector is composed with a reduced number of components externally attached to an IC substrate which mounts integrally main circuit units such as a power source circuit unit, a detection circuit unit and an output circuit unit. The output circuit unit comprises a comparator which compares a judgment signal from the detection circuit unit with a reference signal when the load device is driven by DC power, or compares the voltage of an external DC power source with a predetermined voltage when the device driven by AC power, and an output driver which generates a driving signal for the load device in response to the output signal from the comparator. The detection circuit unit produces the judgment signal only when either the output circuit unit or the power source circuit unit is active.