Abstract: An inverter circuit includes a DC-AC inverter, a sampling circuit, a voltage-current conversion circuit, an isolation circuit and an electronic starter switch. The sampling circuit includes a first and a second diode connected in parallel and opposite in polarity. A forward voltage drop at the first diode blocks the conductance of a first transistor of the voltage-current conversion circuit when there is no load, and a forward voltage drop at the second diode turns on the first transistor when there is a load. The connection of the first and second diodes to a second AC output terminal of the DC-AC inverter nearly has no impact on the AC output of the inverter circuit. These enable the inverter circuit to have low power consumption when there is no load and to be immediately activated upon connection of a load, thereby achieving detection of a load smaller than 0.1 W.

Abstract: A protection circuit for electric outlet includes: a switch control circuit (101), having input terminals connected to a DC power supply or an AC power supply; an automatic load detection circuit (102), having input terminals connected to the switch control circuit (101) and output terminals connected to output terminals of the outlet for detecting whether a load is connected to the output terminals of the outlet and feeding back a load signal (3) to the switch control circuit (101); and a start button (103), connected to the switch control circuit (101). The load signal (3) and the start button (103) together control whether the switch control circuit (101) should output a high-power and high-voltage AC voltage. The combined use of the automatic load detection circuit (102) and the start button (103) guarantees the safety when a child touches the outlet.

Abstract: The present invention discloses a switch control system and its method for a USB charger, wherein the switch control system controls the on-off status of the charging circuit according to whether a charging load is connected or not. The switch control system comprises a first switch and an on-off control unit of the first switch. The first switch connects to a charging power and a converter; the on-off control unit of the first switch connects to the USB output interface and the first switch to control the on-off status of the first switch according to whether the charging load is connected or not. The switch control system and the method for the USB charger disclosed by the present invention realize automatic switching on and off of the USB operating circuit when a load is connected to or removed from the USB output interface.

Abstract: The present invention discloses a compact converter including a compact casing having an air inlet defined thereon, a printed circuit board supported within the compact casing at a position between a top and a bottom wall of the compact casing to form an upper air channel between the printed circuit board and the top wall of the compact casing and a lower air channel between the printed circuit board and the bottom wall of the compact casing, wherein the lower air channel is communicating with the upper channel; a cooling fan is electrically mounted on the printed circuit board at a position aligning with the air inlet for drawing exterior air through the air inlet to the lower air channel to create an air circulation between the lower air channel and the upper air channel, so as to cool down the printed circuit board.

Abstract: The present invention discloses a compact converter including a compact casing having an air inlet defined thereon, a printed circuit board supported within the compact casing at a position between a top and a bottom wall of the compact casing to form an upper air channel between the printed circuit board and the top wall of the compact casing and a lower air channel between the printed circuit board and the bottom wall of the compact casing, wherein the lower air channel is communicating with the upper channel; a cooling fan is electrically mounted on the printed circuit board at a position aligning with the air inlet for drawing exterior air through the air inlet to the lower air channel to create an air circulation between the lower air channel and the upper air channel, so as to cool down the printed circuit board.