Abstract: A self-excitation push-pull type converter with a transformer having a closed magnetic core or iron core, which formed of a main part (52) and a local part (53). The local part reaches magnetic saturation earlier than the main part under the same increasing magnetic field excitation. When the self-excitation push-pull type converter is in a light load state, the efficiency is significantly improved, and further improved in a rated load state. As the number of turns of the coil on the magnetic saturation transformer is reduced, the working frequency of the converter increases while still keeping the loss low. The probability of generating a current peak at the moments of switching on or off is reduced, thereby further improving the efficiency and reducing output ripples.

Abstract: A magnetic core for a transformer, which includes a closed ring with a thick part and a thin part. The thin part is magnetically saturated before the thick part when excited by the same increasing magnetic fields. The thin part only operates briefly at or near first quadrant saturation point or a third quadrant saturation point and, for the rest of the time, it operates in a state between the first quadrant saturation point and the third quadrant saturation point. The present invention overcomes the drawbacks of the conventional magnetic core for a self-excitation push-pull type converter, and significantly improves the efficiency of the converter when it is under a light load, and further improves its efficiency while under a rated load. As the number of turns of the coil on the magnetic saturation transformer is reduced, the working frequency of the converter is improved while still keeping the loss low.

Abstract: A self-excited push-pull converter, where between the bases of the push-pull converter's transistors (TR1, TR2) and the effective power suppler there is provided a constant current source (II), which provides a constant current to the bases of the transistors. With the working voltage increases, the circuit enters into an operating mode not based on the core-saturation working mode, because the transistors' base current is limited by the constant current source and consequently the transistors' collector current cannot increase.

Abstract: An AC to DC circuit includes a rectifier circuit, a voltage detecting circuit, the current source and the output circuit. The rectifier circuit converts the AC power to pulsating DC. The constant current source provides current to the voltage detection circuit and to the control port of the output circuit. The current passing throughout the constant current source is the sum of the current flowing to the voltage detection circuit and to the output circuit. The voltage detection circuit increases with the instantaneous value of the output voltage of the rectifier circuit, it absorbs more current from the current provided by the constant current source and less current flows from the constant current source to the control port of the output circuit. The output circuit amplifies the current of the control port and outputs it to power the load.

Abstract: An AC to DC circuit includes a rectifier circuit, a voltage detecting circuit, the current source and the output circuit. The rectifier circuit converts the AC power to pulsating DC. The constant current source provides current to the voltage detection circuit and to the control port of the output circuit. The current passing throughout the constant current source is the sum of the current flowing to the voltage detection circuit and to the output circuit. The voltage detection circuit increases with the instantaneous value of the output voltage of the rectifier circuit, it absorbs more current from the current provided by the constant current source and less current flows from the constant current source to the control port of the output circuit. The output circuit amplifies the current of the control port and outputs it to power the load.

Abstract: A self-excitation push-pull type converter with a transformer having a closed magnetic core or iron core, which formed of a main part (52) and a local part (53). The local part reaches magnetic saturation earlier than the main part under the same increasing magnetic field excitation. When the self-excitation push-pull type converter is in a light load state, the efficiency is significantly improved, and further improved in a rated load state. As the number of turns of the coil on the magnetic saturation transformer is reduced, the working frequency of the converter increases while still keeping the loss low. The probability of generating a current peak at the moments of switching on or off is reduced, thereby further improving the efficiency and reducing output ripples.

Abstract: An output protection circuit used for a power converter having an operational amplifier, a diode, a number of voltage-dividing resistors, and a switch tube. In this circuit, the voltage-dividing resistors are connected in series to form a voltage-dividing network, of which one node is connected to a reference level end Vref of a PWM control module of the converter, while the other node is grounded. A voltage dividing point M is coupled to an inverting input end of the operational amplifier AR1.

Abstract: A current controlled self-oscillating flyback converter with two transistors. The converter includes a soft start circuit, a MOS transistor, a transformer, a pulse frequency modulation circuit, a reference amplification circuit, an isolation optical coupler and a voltage-stabilized output circuit. The pulse frequency modulation circuit includes a transistor, a third resistor, a capacitor connected in parallel with the third resistor and a fourth resistor. The pulse frequency modulation circuit further includes a transistor current control circuit. The control circuit is connected between the MOS transistor and the transistor.

Abstract: A method for improving the reliability of the welding spot between thin enameled wires and an electronic board and thus securing the connection therebetween, by pulling the terminals of the enameled wires to the back of the electronic board and thereby creating a bearing point on the structure of the board. The bearing point, positioned between the welding spot and the wire terminal, effectively prevents the external forces of stress from directly acting on the welding spot when the terminals of the wire are pulled, swung up and sown, or subjected to other external pulling forces.

Abstract: An isolating type self-oscillating flyback converter is disclosed, which includes a coupled transformer, a FET, a transistor and an electro-optical coupled isolating feedback unit, wherein the input terminal of the circuit is connected to the source of the FET through a primary winding of the coupled transformer, the input terminal of the circuit is connected to the collector of the transistor through a resistor R1 and another resistor R2, the source of the FET is connected to the collector of the transistor, one branch of the drain of the FET is connected to the ground through a resistor, while the other branch is connected to the base of the transistor through the parallel connection body of a resistor and a capacitor, the base of the transistor is connected to the output terminal of a secondary output winding of the coupled transformer through the electro-optical coupled isolating feedback unit; the series connection joint between the said resistor R1 and the said resistor R2 is connected to the ground thr