A master dimmer and one or more dimming control modules use embedded pulse width modulation signal to carry out phase control dimming for lighting equipment. Communication between the master dimmer and the dimming control module(s) is carried out on a communication wire which connects between them. Encoded control signals are embedded onto the voltage carrying communication wire for the communication between the master dimmer and all the dimming control modules. The master dimmer is the only device which connects to the load, such as lamps. Dimming control modules send embedded control commands to the master dimmer and the master dimmer will decode the control commands and then carry out phase control dimming to the load. The combination of master dimmer and dimming control modules provides a simple multi locations dimming control system.

A dimmer includes a power supply circuit including a current limiter and a switch, the power supply circuit electrically coupled to a power source and a load, where current is channeled via the current limiter during a power-on of the dimmer and via the switch during operation of the dimmer after the power-on, a triode for alternating current (TRIAC) control circuit electrically coupled to the power source and the load, where the TRIAC control circuit is structured to control operation of a TRIAC configured to control an amount of power supplied to the load; and a processing unit electrically coupled to the power supply circuit and the TRIAC control circuit, where the processing unit is structured to control the switch and the TRIAC control circuit after the power-on.

A zero-crossing detection method, and devices incorporating the method, enable a selectively enabled bias to pull-up a zero-crossing signal, thereby enabling monitoring of the zero-crossing of both half-cycles of the alternating current (AC). This improves synchronization of the device in noisy environments and enables the detection of dimming problems during either half-cycle. Aspects can detect improper dimmer firing events on either polarity of the power cycle and restore normal dimmer operations when needed.

An LED security light includes an LED load and a motion sensor. The LED load is activated at dusk and deactivated at dawn by a light sensing control unit. At night, the LED load is activated for performing a low level illumination. When a motion signal is detected by the motion sensor, the LED load is switched to perform a high level illumination for a short time period and then resumes to the low level illumination. The low level illumination and the high level illumination are respectively adjustable within respective designed ranges. The LED load is driven by a switching circuitry comprising a driver to output an adequate voltage with constant electric current such that a voltage V across each LED is confined in a range V.sub.th<V<V.sub.max with V.sub.th being a threshold voltage and V.sub.max being a maximum voltage avoiding damaging the LED.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.

A load control device for controlling the power delivered from an AC power source to an electrical load includes a thyristor, a gate coupling circuit for conducting a gate current through a gate of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct the gate current through a first current path to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct the gate current through the first current path again after the firing time, but the gate current is not able to be conducted through the gate from a transition time before the end of the half-cycle until approximately the end of the half-cycle. The load current is able to be conducted through a second current path to the electrical load after the transition time until approximately the end of the half-cycle.

A load control device for controlling power delivered from an AC power source to an electrical load may comprise a thyristor, a gate current path, and a control circuit. The control circuit may be configured to control the gate current path to conduct a pulse of gate current through a gate terminal of the thyristor to render the thyristor conductive at a firing time during a half-cycle of the AC power source. The control circuit may operate in a first gate drive mode in which the control circuit renders the gate current path non-conductive after a pulse time period from the firing time. The control circuit may operate in a second gate drive mode in which the control circuit maintains the gate current path conductive after the pulse time period during the half-cycle.

An LED security light includes a light emitting unit, at least one sensing unit, a loading and power control unit and a power supply unit configured with a first power source and a second power source, wherein a power level detector and a power switching circuitry are installed to select and connect at least one of the first power source and the second power source to the light emitting unit. The light emitting unit is activated at dusk and is deactivated at dawn. When the first power source is used, the LED security light generates a first level illumination. When the second power source is used, the LED security light generates a second level illumination. The first power source is a solar power while the second power source is a backup battery.

Various embodiments may include a dimmer system for controlling the power consumption of a load that can be connected with parallel-connected galvanically isolated dimming channels. The dimmer system may include a plurality of dimming channels, each dimming channel including a sensor for monitoring a temperature of associated switch elements; and a control unit for each dimming channel, the control units configured to shift a respective dimming edge based at least in part on the temperature to distribute power dissipation of the connected load substantially equally across the plurality of dimming channels.