A resonant DC-DC converter may include an input for inputting a DC supply voltage, an output for providing a DC voltage to a load, an output rectifier to convert the converter voltage into a DC voltage, a resonant half-bridge inverter comprising two switches in series with a first serial resonant circuit to adjust the output current of the converter, and a second serial resonant circuit to block DC current in the converter and provide current continuity within the converter. The resonance of the first serial resonant circuit is measured after every start of the converter and each measurement defines the switching frequency of the half-bridge inverter. The switches of the half-bridge inverter wherein the driving of the half-bridge inverter includes a key gap during operation thereof. The resonance frequency of the second serial resonant circuit is at least slightly above the switching frequency of the half-bridge inverter.

A resonant DC-DC converter may include an input for inputting a DC supply voltage, an output for providing a DC voltage to a load, an output rectifier to convert the converter voltage into a DC voltage, a resonant half-bridge inverter comprising two switches in series with a first serial resonant circuit to adjust the output current of the converter, and a second serial resonant circuit to block DC current in the converter and provide current continuity within the converter. The resonance of the first serial resonant circuit is measured after every start of the converter and each measurement defines the switching frequency of the half-bridge inverter. The switches of the half-bridge inverter wherein the driving of the half-bridge inverter includes a key gap during operation thereof. The resonance frequency of the second serial resonant circuit is at least slightly above the switching frequency of the half-bridge inverter.

An LED illumination device for rapidly releasing residual capacitance, which includes a bridge rectifier chip, a current-limiting chip, a light-emitting group, a resistor group and a capacitor. The light-emitting group includes a plurality of first and second LED chips. The resistor group includes a plurality of first and second resistor chips. The first working voltage of the first LED chip is different from the second working voltage of the second LED chip. The first resistance value of the first resistor chip is different from the second resistance value of the second resistor chip. Each first LED chip corresponds to one of the first resistor chips, and each second LED chip corresponds to one of the second resistor chips. When the power supply is turned off, the residual capacitance remaining in the capacitor can be released by cooperation of the first resistor chips and the second resistor chips.

An LED illumination device for rapidly releasing residual capacitance, which includes a bridge rectifier chip, a current-limiting chip, a light-emitting group, a resistor group and a capacitor. The light-emitting group includes a plurality of first and second LED chips. The resistor group includes a plurality of first and second resistor chips. The first working voltage of the first LED chip is different from the second working voltage of the second LED chip. The first resistance value of the first resistor chip is different from the second resistance value of the second resistor chip. Each first LED chip corresponds to one of the first resistor chips, and each second LED chip corresponds to one of the second resistor chips. When the power supply is turned off, the residual capacitance remaining in the capacitor can be released by cooperation of the first resistor chips and the second resistor chips.

An AC two-wire LED high voltage lamp string with synchronous dimming and color adjustment comprises a high voltage controller and a lamp string group, wherein the high voltage controller comprises a control box, and a first power supply module, a switch control circuit and a first microcontrol unit which are arranged in the control box and connected in sequence; the first power supply module is connected with the switch control circuit and the first microcontrol unit; a second microcontrol unit. The present invention modulates and encodes a high voltage sine wave using the switch control circuit at the controller end and demodulates the sine wave at a bulb end to realize the functions of color change timing, flashing, timing and light control of lamp strings. The lamp strings can be used individually or connected in series and in parallel for use, to satisfy different needs of consumers.

An AC two-wire LED high voltage lamp string with synchronous dimming and color adjustment comprises a high voltage controller and a lamp string group, wherein the high voltage controller comprises a control box, and a first power supply module, a switch control circuit and a first microcontrol unit which are arranged in the control box and connected in sequence; the first power supply module is connected with the switch control circuit and the first microcontrol unit; a second microcontrol unit. The present invention modulates and encodes a high voltage sine wave using the switch control circuit at the controller end and demodulates the sine wave at a bulb end to realize the functions of color change timing, flashing, timing and light control of lamp strings. The lamp strings can be used individually or connected in series and in parallel for use, to satisfy different needs of consumers.

An LED illumination device for rapidly releasing residual capacitance, which includes a bridge rectifier chip, a current-limiting chip, a light-emitting group, a resistor group and a capacitor. The light-emitting group includes a plurality of first and second LED chips. The resistor group includes a plurality of first and second resistor chips. The first working voltage of the first LED chip is different from the second working voltage of the second LED chip. The first resistance value of the first resistor chip is different from the second resistance value of the second resistor chip. Each first LED chip corresponds to one of the first resistor chips, and each second LED chip corresponds to one of the second resistor chips. When the power supply is turned off, the residual capacitance remaining in the capacitor can be released by cooperation of the first resistor chips and the second resistor chips.

An LED illumination device for rapidly releasing residual capacitance, which includes a bridge rectifier chip, a current-limiting chip, a light-emitting group, a resistor group and a capacitor. The light-emitting group includes a plurality of first and second LED chips. The resistor group includes a plurality of first and second resistor chips. The first working voltage of the first LED chip is different from the second working voltage of the second LED chip. The first resistance value of the first resistor chip is different from the second resistance value of the second resistor chip. Each first LED chip corresponds to one of the first resistor chips, and each second LED chip corresponds to one of the second resistor chips. When the power supply is turned off, the residual capacitance remaining in the capacitor can be released by cooperation of the first resistor chips and the second resistor chips.

A power adapter with a sensing control function for a lamp load comprises a plug case, a pin set, and a circuit board. The plug case has an exterior surface having an operation area. The pin set is mounted on the plug case. The circuit module is mounted in the plug case, is electrically connected to the pin set, and has a sensor board comprising a sensing conductor and a controller electrically connected to the sensing conductor. A position of the sensing conductor corresponds to a position of the operation area of the exterior surface of the plug case.

A power adapter with a sensing control function for a lamp load comprises a plug case, a pin set, and a circuit board. The plug case has an exterior surface having an operation area. The pin set is mounted on the plug case. The circuit module is mounted in the plug case, is electrically connected to the pin set, and has a sensor board comprising a sensing conductor and a controller electrically connected to the sensing conductor. A position of the sensing conductor corresponds to a position of the operation area of the exterior surface of the plug case.