A multiple location dimming system may include a smart dimmer (e.g., a main load control device) and one or more remote dimmers (e.g., accessory devices) for controlling the amount of power delivered to a lighting load. The multiple location dimming system may be installed in place of a multiple location switch system (e.g., having three, four, or more multi-way switches), and may not require a neutral connection at any of the control devices of the multiple location dimming system. The main load control device and the accessory devices of the multiple location dimming system may be configured to display a present intensity level of a lighting load on one or more visual indicators. The accessory devices may have the same or different user interfaces as the main load control device, and may provide additional functionality over that which the main load control device offers.

Disclosed is an electrical dimmer that upon activation sends a forward-phase modulated test power pulse to a connected load, receives from the load a response pulse, compares the width of the two pulses, and, depending upon the results of the comparison, operates in either forward- or reverse-phase modulation. The dimmer may respond to an intensity target by setting a pulse-width modulation duty cycle, the setting based on an intensity-translation curve. The translation curve may be based on a mapping between luminance and human visual perception of brightness. Some dimmers support a minimum intensity setting, and some dimmers configure themselves to the frequency of the incoming alternating-current power source.

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.

System and method for controlling one or more light emitting diodes. For example, the system includes: a phase detector configured to process information associated with a rectified voltage generated by a rectifier and related to a TRIAC dimmer, the rectified voltage corresponding to a first waveform during a first half cycle of an AC voltage and corresponding to a second waveform during a second half cycle of the AC voltage, the phase detector being further configured to generate a phase detection signal representing a first time duration during which the first waveform indicates that the rectified voltage is larger than a predetermined threshold and representing a second time duration during which the second waveform indicates that the rectified voltage is larger than the predetermined threshold; and a mode detector configured to process information associated with the rectified voltage.

A multiple location dimming system may include a smart dimmer (e.g., a main load control device) and one or more remote dimmers (e.g., accessory devices) for controlling the amount of power delivered to a lighting load. The multiple location dimming system may be installed in place of a multiple location switch system (e.g., having three, four, or more multi-way switches), and may not require a neutral connection at any of the control devices of the multiple location dimming system. The main load control device and the accessory devices of the multiple location dimming system may be configured to display a present intensity level of a lighting load on one or more visual indicators. The accessory devices may have the same or different user interfaces as the main load control device, and may provide additional functionality over that which the main load control device offers.

Disclosed is an electrical dimmer that upon activation sends a forward-phase modulated test power pulse to a connected load, receives from the load a response pulse, compares the width of the two pulses, and, depending upon the results of the comparison, operates in either forward- or reverse-phase modulation. The dimmer may respond to an intensity target by setting a pulse-width modulation duty cycle, the setting based on an intensity-translation curve. The translation curve may be based on a mapping between luminance and human visual perception of brightness. Some dimmers support a minimum intensity setting, and some dimmers configure themselves to the frequency of the incoming alternating-current power source.

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.

A load control system includes a switch, a controller, an additional functioning unit, a power source, and an adjuster. The controller is configured to switch the switch between a conduction state and a non-conduction state. The switch is electrically connected in series to a load with respect to an alternating-current power source. The additional functioning unit is configured to perform a process different from switching operation of the switch. The power source receives electric power supplied from the alternating-current power source to generate electric power to be supplied to the controller and the additional functioning unit. The adjuster adjusts a supply time period during which the power source is supplied with electric power from the alternating-current power source in a maximum load state of a state where the additional functioning unit normally operates, electric power consumption by the additional functioning unit being maximum in the maximum load state.

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.