A parallel sequenced LED light string includes a plurality of LED modules. The LED modules are connected in parallel through a power wire with a plurality of wire resistances. Each of the LED modules includes an impedance component capable of providing an impedance characteristic. The parallel-connected LED modules receive a supply power, and the LED modules respectively get different voltages through the wire resistances and the impedance components from the supply power so as to sequencing the LED modules.

A light-emitting diode (LED) array includes an array of pixel assemblies and a pulse width modulator. The pulse width modulator generates pulse width modulation (PWM) signals for controlling a duty cycle of each of the pixels. The pixel assemblies each include an LED, a switching circuit, and a close loop circuit. The switching circuit receives a PWM signal and alternately turns on and off the LED based on the PWM signal. The close loop circuit regulates an LED current provided by the switching circuit to the LED based on a feedback signal received from the switching circuit.

A discrete component linear circuit of a line is provided, including a switch S1, a fuse F1, a varistor MOV1, a rectifier DB1, a triode Q1 to a triode Q6, and a resistor R1 to a resistor R6, wherein an input end of the switch S1 is connected to an input end L of a power supply for input, and an output end of the switch S1 is connected to an input end of the fuse F1. When an input voltage increases, a current increases, and resistance values of a thermistor T1, a thermistor T2 and a thermistor T3 increase due to temperature rise. The resistance increases synchronously when the voltage increases, so that the current is maintained in a relatively stable interval. Therefore, the voltage bearing capacity when an LED lamp works is increased, and more LED lamps may be used in parallel.

A discrete component linear circuit of a line is provided, including a switch S1, a fuse F1, a varistor MOV1, a rectifier DB1, a triode Q1 to a triode Q6, and a resistor R1 to a resistor R6, wherein an input end of the switch S1 is connected to an input end L of a power supply for input, and an output end of the switch S1 is connected to an input end of the fuse F1. When an input voltage increases, a current increases, and resistance values of a thermistor T1, a thermistor T2 and a thermistor T3 increase due to temperature rise. The resistance increases synchronously when the voltage increases, so that the current is maintained in a relatively stable interval. Therefore, the voltage bearing capacity when an LED lamp works is increased, and more LED lamps may be used in parallel.

A lighting apparatus includes a filter tuner, a bridge rectifier, multiple types of LED modules, a monitor circuit, and a current source. The filter tuner is connected to a manual switch and an external AC power. The filter tuner changes a conductive angle of the external AC power to an adjusted AC input. The bridge rectifier receives the adjusted AC input to generate a DC output. Multiple types of LED modules are disposed for emitting lights of multiple color temperatures. The monitor circuit monitors the conductive angle to generate a control signal. The current source, according to the control signal, generates multiple corresponding driving currents respectively supplied to the multiple types of LED modules to mix a desired color temperature. The desired color temperature is associated with the conductive angle according to a predetermined relation.

A lighting apparatus includes a filter tuner, a bridge rectifier, multiple types of LED modules, a monitor circuit, and a current source. The filter tuner is connected to a manual switch and an external AC power. The filter tuner changes a conductive angle of the external AC power to an adjusted AC input. The bridge rectifier receives the adjusted AC input to generate a DC output. Multiple types of LED modules are disposed for emitting lights of multiple color temperatures. The monitor circuit monitors the conductive angle to generate a control signal. The current source, according to the control signal, generates multiple corresponding driving currents respectively supplied to the multiple types of LED modules to mix a desired color temperature. The desired color temperature is associated with the conductive angle according to a predetermined relation.

A power converter includes a primary winding and multiple output windings to provide multiple independently controlled and regulated outputs with a common return line. The outputs are coupled to independently regulate constant current, constant voltage, or both constant current and constant voltage outputs. A secondary control block is coupled to control a synchronous rectifier switch coupled to the common return line to synchronize switching with a primary side power switch to provide complementary conduction of the primary winding and the multiple output windings. A plurality of controlled power pulse switches is coupled to the multiple output windings. A request of a power pulse from each of the outputs is transferred through the secondary control block to a primary switch control block to turn on the primary side power switch to transfer a power pulse to the multiple output windings and through controlled power pulse switches to the outputs.

A power converter includes a primary winding and multiple output windings to provide multiple independently controlled and regulated outputs with a common return line. The outputs are coupled to independently regulate constant current, constant voltage, or both constant current and constant voltage outputs. A secondary control block is coupled to control a synchronous rectifier switch coupled to the common return line to synchronize switching with a primary side power switch to provide complementary conduction of the primary winding and the multiple output windings. A plurality of controlled power pulse switches is coupled to the multiple output windings. A request of a power pulse from each of the outputs is transferred through the secondary control block to a primary switch control block to turn on the primary side power switch to transfer a power pulse to the multiple output windings and through controlled power pulse switches to the outputs.

A light fixture of a light system is configured to be dimmable using a dimming signal that is either a direct-current (DC) dimming signal or an alternating-current (AC) dimming signal. For example, a 0-10 volt DC dimming signal could be used, or a 120 volt AC dimming signal could be used. A dimming controller in the light fixture is configured to receive both a DC and an AC dimming signals and adjust a brightness and/or color of a light based on the dimming signal.

A light emitting diode (LED) circuit is disclosed having an LED having a plurality of current paths. A controller may be included for controlling the LEDs. The LED is connected to a first transistor and a first current sink to drive a constant current through the LED through a first current path. At least one cloning transistor can establish a parallel current path through the LED and parallel to the first current path and is connected such that the constant current in the first current sink is duplicated in the parallel current path.