Abstract: A protection device for an output power source of an electronic device includes a compare unit, an invert unit and a switch unit. The compare unit is coupled with the output power source and receives an input voltage value and a predetermined voltage value from the output power source. The compare unit compares the input voltage value and the predetermined voltage value to generate a comparison signal. The invert unit is coupled with the compare unit and receives the comparison signal to generate an inverted signal. The switch unit is coupled with the output power source and the invert unit, and receives the inverted signal. If the input voltage value is higher than the predetermined voltage value, the switch unit turns on and outputs an output voltage, and if the input voltage value is lower than the predetermined voltage value, the switch unit turns off and has no output.

Abstract: A fan with failure detecting function includes a power input terminal, a current limiting resistor, a light emitting diode (LED), and a fan motor. The power input terminal is coupled to the anode of the LED via the current limiting resistor. The cathode of the LED is coupled to one terminal of the fan motor, another terminal of the fan motor is grounded.

Abstract: An over-voltage protection circuit assembly includes a connector and an over-voltage protection circuit. The connector includes a power terminal. The over-voltage protection circuit includes a voltage input terminal, and a voltage output terminal. The voltage output terminal connected to the voltage input terminal via a resistor. A relay includes an inductance coil and a switch. The inductance coil is connected between the voltage input terminal and ground. A warning unit is connected in series with the switch of the relay between the voltage input terminal and ground. A voltage regulating diode is connected between the voltage output terminal and ground. The anode of the voltage regulating diode is connected to ground, and the cathode of the voltage regulating diode is connected to the voltage output terminal.

Abstract: A short-circuit protection circuit includes a power supply, a first resistor, and an optocoupler. The optocoupler includes a light-emitting diode and a phototransistor, one end of the first resistor is connected to the anode of the power supply and the other end of the first resistor is connected to the anode of the light-emitting diode, the cathode of the light-emitting diode is grounded, the collector of the phototransistor is connected to the anode of the power supply, and the emitter of the phototransistor is grounded via a load circuit, the cathode of the power supply is grounded, when a short circuit occurs in the load circuit, the light-emitting diode turns off, the phototransistor turns off accordingly, and the voltage of the power supply does not provide voltage to the load circuit.

Abstract: A voltage comparator circuit includes a voltage input terminal, a first resistor, a second resistor, a first transistor, a second transistor, and a voltage output terminal connected to the collector of the second transistor. The voltage input terminal is connected to ground via the first and second resistors in turn. A node between the first and second resistors is connected to the base of the first transistor. The emitter of the first transistor is grounded. The collector of the first transistor is connected to a direct current (DC) power supply and the base of the second transistor. The emitter of the second transistor is connected to the DC power supply.

Abstract: An over-voltage protection circuit assembly includes a connector and an over-voltage protection circuit. The connector includes a power terminal. The over-voltage protection circuit includes a voltage input terminal, and a voltage output terminal. The voltage output terminal connected to the voltage input terminal via a resistor. A relay includes an inductance coil and a switch. The inductance coil is connected between the voltage input terminal and ground. A warning unit is connected in series with the switch of the relay between the voltage input terminal and ground. A voltage regulating diode is connected between the voltage output terminal and ground. The anode of the voltage regulating diode is connected to ground, and the cathode of the voltage regulating diode is connected to the voltage output terminal.

Abstract: A fan with failure detecting function includes a power input terminal, a current limiting resistor, a light emitting diode (LED), and a fan motor. The power input terminal is coupled to the anode of the LED via the current limiting resistor. The cathode of the LED is coupled to one terminal of the fan motor, another terminal of the fan motor is grounded.

Abstract: A compatible circuit for integrated circuits (ICs) includes three input terminals coupled to corresponding pins of an IC, and three function terminals corresponding to the three input terminals. Each input terminal coupled to the three function terminals via three transmission lines, each transmission line has an open segment, and each input terminal is electrically coupled to a corresponding function terminal by selectively mounting a connection component on the open segment of the corresponding transmission line according to a specification of the IC.