Abstract: A power feed device feeds power to a power receiving device using a magnetic field. The power feed device includes a coil, a first communication component, and a controller. The coil generates the magnetic field. The first communication component communicates with the power receiving device. The controller controls generation of the magnetic field based on a card information.

Abstract: A wireless power supply device includes a resonant circuit including a power supply coil and a resonant capacitor. The wireless power supply device also includes a controller that changes a waveform of power in the resonant circuit and causes a phase difference between a phase of a drive signal that drives the resonant circuit and a phase of current flowing through the power supply coil to be substantially 0.

Abstract: A lighting device includes a light source component, a circuit board component, and a case component. The circuit board component is configured to supply power to the light source component. The case component houses the circuit board component in an interior of the case component. The circuit board component includes first and second circuit board components. The first circuit board component has a first mounting surface on which a first electronic part is mounted. The second circuit board component has a second mounting surface on which a second electronic part is mounted. The second mounting surface of the second circuit board component overlaps with the first mounting surface of the first circuit board component.

Abstract: A power supply circuit includes a rectifying circuit, a transformer, and a current controller. The rectifying circuit is configured to rectify power of an AC power supply and supply the power to a light source. The transformer is electrically disposed between the AC power supply and the rectifying circuit. The transformer includes a primary winding and an auxiliary winding. The current controller is configured to adjust an amount of current flowing to the light source by detecting a voltage signal of the auxiliary winding and a signal based on the current flowing to the light source.