An AC-DC power supply receives input AC power and outputs DC power. The converter includes a high power factor bridge rectifier, a barrier circuit with resistor(s) and capacitor(s), and a step-down switching DC-DC converter to step-down a first DC voltage to a second, lower, DC voltage for output. Additionally, fault-protection is provided by redundancy in diodes on diode legs of a bridge rectifier and capacitor(s) of a filter circuit thereof, and a fault-protection circuit to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

An AC-DC power supply receives input AC power and outputs DC power. The converter includes a high power factor bridge rectifier, a barrier circuit with resistor(s) and capacitor(s), and a step-down switching DC-DC converter to step-down a first DC voltage to a second, lower, DC voltage for output. Additionally, fault-protection is provided by redundancy in diodes on diode legs of a bridge rectifier and capacitor(s) of a filter circuit thereof, and a fault-protection circuit to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

A driving device comprises a first transistor (B13), a second transistor (B14), and a resistance element. The first transistor (B13) has one terminal receiving a pulsed current and a control terminal connected to the one terminal. The second transistor (B14) has one terminal connected to at least one load, the other terminal connected to a reference potential together with the other terminal of the first transistor (B13), and a control terminal connected to the control terminal of the first transistor (B13). The resistance element is connected between the control terminal of the first transistor (B13) and the other terminal of the first transistor (B13).

This disclosure includes systems, methods, and techniques for controlling delivery of power to one or more strings of light-emitting diodes (LEDs). For example, a circuit includes a power converter configured to generate an electrical current, a switching device, and a sensor. The sensor is configured to compare a magnitude of the electrical current to a threshold, and in response to the magnitude exceeding the threshold, cause the switching device to turn on in order to sink a portion of the electrical current to prevent the magnitude of the electrical current from exceeding the threshold. When the switching device is turned on, the electrical current is divided into an undesired electrical current that flows across the switching device and a desired electrical current that flows to the string of LEDs.

This disclosure includes systems, methods, and techniques for controlling delivery of power to one or more strings of light-emitting diodes (LEDs). For example, a circuit includes a power converter configured to generate an electrical current, a switching device, and a sensor. The sensor is configured to compare a magnitude of the electrical current to a threshold, and in response to the magnitude exceeding the threshold, cause the switching device to turn on in order to sink a portion of the electrical current to prevent the magnitude of the electrical current from exceeding the threshold. When the switching device is turned on, the electrical current is divided into an undesired electrical current that flows across the switching device and a desired electrical current that flows to the string of LEDs.

A circuit comprises an optical coupling including an illuminator optically coupled to an optical sensor to output a voltage from the optical sensor based on intensity of illumination from the illuminator. The circuit includes a voltage input node with a resistance connected in series between the voltage input and a Zener diode. A method includes powering an illuminator with current from a first voltage input node. The method includes sensing illumination level in illumination from the illuminator with a sensor and outputting output proportionate to illumination sensed by the sensor indicative of voltage detected at the voltage input node. The method can include limiting current between the voltage input node and the illuminator.

A system includes a first device and N number of second devices. The first device generates, based on a DC input signal, a first DC output voltage and a first enabling signal, enabled by which, a first one of the second devices generates a second DC output voltage and a second enabling signal based on the DC input signal. In a similar manner, an i.sup.th one of the second devices is enabled by an (i−1).sup.th one of the second devices to generate an (i+1).sup.th DC output voltage and an (i+1).sup.th enabling signal based on the DC input signal. A starting time point of a logic-high level portion of each enabling signal is later than a peak time point corresponding to a peak voltage of the corresponding DC output voltage.

The disclosure provides a lighting device that provides light via one or more non- incandescent lamps that can be moved and arranged while operating. The lighting device includes a non-opaque shroud, or casing, that sits upon a base to create a volume within which the non-incandescent lamps rest and can be moved while still providing light. The non- incandescent lamp can use one or more light-emitting diodes (LEDs). The non-incandescent lamps can provide illumination with minimal heat and low power consumption that contributes to user interaction and can be battery powered. In addition to a non-incandescent lamp, a lighting device having at least one of the non-incandescent lamps is disclosed. Additionally, a lighting system having at least one of the lighting devices and a lighting control application is provided herein.

LED related lighting methods and apparatus are described. Various features relate to water tight light fixtures. Some of the fixtures are spotlights while other fixture are intended for in ground use. The light fixtures in at least some embodiments include power control features. In spotlight embodiments beam angle and power or light output can be controlled without opening the light assembly or compromising the water tight seals which also protect against dirt. In ground embodiments support tilt angle setting which allow a user to set the light fixture to one or more tilt angles. Beam angle can also be changed in some embodiments as well as power control. Beam angle, power control and tilt angle adjustments are supported in some embodiments but need not be supported in all embodiments with some embodiments using one or more of the described features but not all features.

The present disclosure is for a light-emitting diode light string control system, which comprises: a switching unit having a power input end, a power output end connected to the light string, and a controlled end. A control unit is connected to the controlled end of the switching unit. A second power-generating unit is also connected to the light-emitting diode light string. The light-emitting control command sent by the control unit is in a carrier wave mode to realize brightness variation of the light string, which saves costs and simplifies the control circuit. A short-circuit protection unit is employed to provide fast and reliable response in real time.