Photosensor circuits including a regulated power supply comprising a power circuit configured to provide a regulated power signal to a comparator of a pulse-width modulator

摘要

Photosensor circuits include a relay coil configured to control application of an alternating current (AC) power source to a load. The circuit includes a pulse width modulator circuit configured to generate a pulse width modulated signal having a pulse width that varies responsive to an average voltage across the relay coil. A drive transistor coupled to the relay coil controls the average voltage across the relay coil responsive to the pulse width modulated signal. A photo control circuit is configured to control application of the pulse width modulated signal to the drive transistor responsive to a detected light level. A power circuit coupled to the power source is configured to provide a regulated power signal to a comparator of the pulse width modulator circuit.