IMPROVED POWER STEALING FOR A THERMOSTAT USING A TRIAC WITH FET CONTROL

摘要

An electronic thermostat circuit has improved power stealing for controlling an AC control device. The circuit comprises a source of AC control power coupled to an electronic switch means having an electronic switch means control input. The electronic switch means controls the AC control device. The diode bridge controls the electronic switch means by a DC control signal applied to the diode bridge means DC connection. The amplifier means has an amplifier input for controlling the state of the amplifier and an amplifier output for generating the DC control signal. An isolated gate FET means is electrically coupled to the amplifier input for controlling the state of the amplifier. The isolated gate FET means is powered by the current derived from the source of AC control power by power stealing. The digital signal controls the state of the AC control.