Abstract: The present X-ray protector requires no raising of a voltage to be impressed to a cathode ray tube (CRT) and no complicated control procedure for testing the X-ray protector's operation. The voltage applied to the CRT is detected by a detection winding of a flyback transformer and a detection circuit. An input line, which includes a resistor inputs a signal based on the detected voltage to a microcomputer. The microcomputer controls whether a transistor is conductive or unconductive. An emitter of the transistor is connected to one terminal of the resistor, and a collector is connected to the other terminal of the resistor. When the transistor is conductive both ends of the resistor are short-circuited causing the electric voltage of a signal input to the microcomputer to be raised, thereby enabling testing of the X-ray protector without the need to apply a higher than normal voltage to the CRT.

Abstract: A power supply protection circuit for stopping a power supply to electrical equipments in case a normal power voltage is not outputted from a direct current power supply and an excess voltage or a reduced voltage is outputted. The power supply protection circuit according to the present invention is constituted of a power source line for supplying a direct current power, via relay contacts of a relay, to an electrical equipment, a first circuit for detecting an excess voltage and a reduced voltage, a second circuit, and a relay operation circuit.

Abstract: A power supply protection circuit for stopping a power supply to electrical equipments in case a normal power voltage is not outputted from a direct current power supply and an excess voltage or a reduced voltage is outputted. The power supply protection circuit according to the present invention is constituted of a power source line 2 for supplying a direct current power, via relay contacts 3a and 3b of a relay, to a electrical equipment 15, a first circuit 10 for detecting an excess voltage and a reduced voltage, a second circuit 20, and a relay operation circuit 25. In the first circuit 10, when a first excess voltage-detecting element 14 detects an excess voltage, a first semiconductor-switching element 12 becomes unconductive, and when first excess voltage detecting element 14 does not detect an excess voltage, a first semiconductor-switching element 12 becomes conductive.

Abstract: The object of the present invention is to provide an X-ray protector that requires no raising a voltage to be impressed to a Braun tube and no complicated control procedure for testing at the time of conducting a test of an X-ray protector's operation. The voltage impressed to the Braun tube 8 of a TV receiver is detected by the detection winding 6c of the flyback transformer 6 and the detection circuit 11, and the input line 15, which conducts the operation of the X-ray protector by inputting a signal based on the detected voltage to the microcomputer 1, is provided with the resistor R1. And, whether the transistor 12 is conductive or unconductive depends on the control by the microcomputer 1. An emitter terminal of the transistor 12 is connected to one terminal of the resistor R1, and a collector terminal is connected to the other terminal of the resistor R1.