A thyristor or triac control circuit includes a first capacitive element that is series-connected with a first diode between a first terminal and a second terminal intended to be coupled to a gate of the thyristor or triac. A second capacitive element is coupled between the second terminal and a third terminal intended to be connected to a conduction terminal of the thyristor or triac on the gate side of the thyristor or triac. A second diode is coupled between the third terminal and a node of connection of the first capacitive element and first diode.

A load control device for controlling the amount of power delivered from an AC power source to an electrical load is operable to conduct enough current through a thyristor of a connected dimmer switch to exceed rated latching and holding currents of the thyristor. The load control device comprises a controllable-load circuit operable to conduct a controllable-load current through the thyristor of the dimmer switch. The load control device disables the controllable-load circuit when the phase-control voltage received from the dimmer switch is a reverse phase-control waveform. When the phase-control voltage received from the dimmer switch is a forward phase-control waveform, the load control device is operable to decrease the magnitude of the controllable-load current so as to conduct only enough current as is required in order to exceed rated latching and holding currents of the thyristor.

A power supply device that allows individual control of an output voltage of a main transformer and an output voltage of a teaser transformer while utilizing output characteristics of the respective transformer when a Scott connected transformer has control equipment arranged on the input side thereof, including first control equipment arranged in one of two phases of the main transformer on the input side in order to control a voltage or a current and second control equipment arranged in one end of a primary coil of the teaser transformer on the input side in order to control a voltage or a current, the control equipment controlling an output voltage of the main transformer and an output voltage of the teaser transformer individually.

A multi-winding single-stage multi-input boost type high-frequency link's inverter with simultaneous/time-sharing power supplies, having the circuit structure formed by connecting a plurality of mutually isolated high-frequency inverter circuits having an input filter and an energy storage inductor, a common output cycloconverter and filter circuit by a multi-input single-output high-frequency transformer. Each input end of the multi-input single-output high-frequency transformer is connected in one-to-one correspondence to the output end of each high-frequency inverter circuit. The output end of the multi-input single-output high-frequency transformer is connected to the input end of the output cycloconverter and filter circuit. The inverter has the following characteristics: multiple input sources are connected to a common ground or a non-common ground. The multiple input sources supply power to load in a simultaneous/time-sharing manner. The output and input high-frequency isolation is performed. The output cycloconverter and filter circuit is shared.

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 dimmer is provided for controlling power to a load, the dimmer having a ground leakage power supply deriving power from a connection of the dimmer to ground. The power supply may be a switching-mode power supply that can be the sole or primary power supply to power operation of the dimmer, including operation of the controller.

An electronically controlled transformer, which is used for AC power supply, cutting off the sinusoidal waveform of voltage to change the RMS voltage. The electronically controlled transformer comprises a casing, socket holes and socket tabs for output and a circuit board. The circuit board is provided with an input terminal, a silicon controlled rectifier or field-effect transistor, an output terminal and a control module. The live wire and neutral wire of input terminal are connected by a rectifier or bridge rectifier. The positive output of rectifier or bridge rectifier is connected to a voltage regulation module. The voltage regulation module is connected to a control module. The control module comprises a control IC and a trigger and driving part. The trigger and driving part has an optical coupler. The switching pin of control IC is connected to the transmitting terminal of optical coupler.

The present invention relates to a power tool monitored by tracking a motor current and control methods thereof. The present invention is mainly about a microprocessor electrically connected to a motor through a drive unit and a current detecting-and-converting module. The microprocessor receives an AC synchronizing signal, and sends a first control signal to the drive unit according to the AC synchronizing signal to drive the motor. The current detecting-and-converting module detects and converts the motor current and output to the microprocessor, thereby the microprocessor detects a per unit time current which is converted into a corresponding pressure value, and then the microprocessor sends a second control signal to the drive unit according to the pressure value to control the operation status of the motor. By detecting and tracking the per unit time current, the purpose of load monitoring and motor protection can be achieved.

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.

The present invention allows individual control of an output voltage of a main transformer and an output voltage of a teaser transformer while utilizing output characteristics of the respective transformer when a Scott connected transformer has control equipment arranged on the input side thereof, including first control equipment arranged in one of two phases of the main transformer on the input side in order to control a voltage or a current and second control equipment arranged in one end of a primary coil of the teaser transformer on the input side in order to control a voltage or a current, the control equipment controlling an output voltage of the main transformer and an output voltage of the teaser transformer individually.