An apparatus for controlling one or more switched high power loads (or heating elements). The apparatus including: one or more switched high power loads (or heating elements), each high power load being powered from a common alternating current power source, and wherein each load is independently switched using a switching signal for zero crossing switching to achieve a desired average power output; the switching signal is generated that comprises a repeated switching sequence; the switching sequence indicates a respective selecting activation for each of the switched high power load over a sequence of half or full cycles.

A drive circuit for driving an electro-optical device like an optically switchable glazing, e.g. a glass panel provided with a PDLC or SPD layer, comprises a set of input terminals for receiving an alternating input voltage at a first frequency; a set of output terminals for supplying an alternating output voltage at a second frequency; a control circuit generating a control signal dependent on an input signal, the input signal representing a charge state of the electro-optical device; and a current-direction circuit for controlling a current-flow direction of an electrical current in response to the control signal. The control circuit and the current-direction circuit are thereby configured to control the second frequency such that the electro-optical device is prevented from degradation, while keeping an energy consumption low.

A power supply system for an electric arc furnace includes an AC input connectable to an electrical grid and an AC output for supplying at least one power electrode of the arc furnace; a resonant circuit interconnected between the AC input and the AC output. The resonant circuit includes a controllable bypass switch for connecting and disconnecting a circuit input and a circuit output of the resonant circuit and a capacitor and a main inductor connected in parallel with the bypass switch.

The present disclosure relates to electronic equipment, and especially relates to an alternating current transmission circuit. The alternating current transmission circuit includes power supply circuit and a switch circuit coupled with the power supply circuit. The switch circuit includes a main control circuit, a surge detection circuit, and a first switch device connected in series in the power supply circuit. The main control circuit is signal connected with the first switch device and configured to control on-off of the power supply circuit by controlling the first switch device. An input terminal of the surge detection circuit is connected with the power supply circuit, and an output terminal of the surge detection circuit is connected with the main control circuit.

An electronic system sharing power of a doorbell includes a switch circuit and an electronic device. The first and second connection terminals of the switch circuit are respectively coupled to two doorbell contacts. The second and third connection terminals of the switch circuit are respectively coupled to two ends of a doorbell. Two power terminals of the electronic device are respectively coupled to two switch contacts. A function circuit of the electronic device is coupled between the two power terminals. In a normal mode, the first connection terminal is conducted to the second connection terminal inside the switch circuit, and the two power terminals are disconnected from each other by a doorbell actuating unit of the electronic device. In a ringing mode, the doorbell actuating unit short-circuits the two power terminals, and the first connection terminal is conducted to the third connection terminal inside the switch circuit.

A power converter comprises a primary stage including four switches forming a first H bridge; a control circuit capable of applying a first control signal to the first H bridge; a secondary stage including four switches forming a second H bridge; a control circuit capable of applying a second control signal to the second H bridge; and a power transmission stage coupling the primary stage to the secondary stage, wherein the control circuit of the secondary stage is electrically isolated from the control circuit of the primary stage. During a measurement period of a synchronization phase, the switches of the secondary stage are maintained in a short-circuit configuration while the switches of the primary stage are controlled in switched mode.

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.

An electronic system sharing power of doorbell includes a switch circuit and an electronic device. The first and second connection terminals of the switch circuit are respectively coupled to two doorbell contacts. The second and third connection terminals of the switch circuit are respectively coupled to two ends of a doorbell. Two power terminals of the electronic device are respectively coupled to two switch contacts. A function circuit of the electronic device is coupled between the two power terminals. In a normal mode, the first connection terminal is conducted to the second connection terminal inside the switch circuit, and the two power terminals are disconnected to each other by a doorbell actuating unit of the electronic device. In a ringing mode, the doorbell actuating unit short-circuits the two power terminals, and the first connection terminal is conducted to the third connection terminal inside the switch circuit.

The instant disclosure concerns a power converter including: a primary stage (110) including at least one first cut-off switch (S.sub.11, S.sub.12, S.sub.13, S.sub.14); a control circuit (112) capable of applying a first control signal to said at least ore first switch; a secondary stage (130) including at least one second cut-off switch (S.sub.21, S.sub.22, S.sub.23, S.sub.24); a control circuit (132) capable of applying a second control signal to said at least one second switch; a power transmission stage (120) coupling the primary stage (110) to the secondary stage (130), wherein the control circuit (132) of the secondary stage is electrically isolated from the control circuit (112) of the primary stage.

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.