Patent ID: 7821761

Claim:
A current inductive timer socket comprising: a principle relay circuit including an output relay and a voltage input terminal, the output relay controls a power transmitted from the voltage input terminal to a household electric appliance socket or a second current inductive timer socket; a reed relay circuit including a capacitor, a plurality of diodes, a reed relay and a resistance, and being used to receive signals from exciting transistors of a time switch circuit, and to start the output relay; a counter circuit including a DC rectifier, seven series-connected counters, and a time select switch; a holding circuit including a neon light, a photodiode, an operational amplifier, a transistor, a diode and a resistance; wherein the time switch circuit includes three time switches, and three series-connected exciting transistors, and the time units of the three time switches are minute, ten minute and hour; an inductive and amplification circuit including a transformer parallel-connected to a rated resistor, a set of two-stage operational amplifiers, a resistance, and a capacitor; an overload detecting circuit being set with a predetermined maximum value, when a signal processed by the inductive and amplification circuit exceeds the predetermined maximum value, the reed relay and the output relay are actuated to turn off a power source; the household electric appliance socket for connection of a household electric appliance; the second current inductive timer socket for connection of another current inductive timer socket; when an electric appliance is connected to the current inductive timer socket, a signal of voltage drop will be produced at both ends of the rated resistance, and then will be amplified by the operational amplifier and transmitted to the counter circuit and the overload detecting circuit, when the counter circuit counts to a predetermined value, the time switches will send signals to the three exciting transistors, so as to start the reed relay and the output relay, thus cutting off the power supply to the electric appliance, meanwhile, the holding circuit will keep the output relay on, thus a timing operation is finished, after that, if the user turns off a switch of the electric appliance, the holding circuit will make the output relay switch off, returning to its original state, on the other hand, if electric appliance is overloaded or a short circuit occurs, the current flowing through the rated resistance will become very large, the signal flowing from the amplification circuit to the overload detecting circuit will also increase and once it exceeds the predetermined maximum value, the overload detecting circuit will actuate the reed relay and the output relay to turn off the power source.