Patent ID: 7919883
Filing Date: 2011-04-05
Classification: H03K,H04B

Abstract:
1. An annunciator circuit comprising: a remote circuit including a voltage regulator and sensing circuit; a two-wire adapter circuit spaced from said remote circuit comprising a current shunt monitor monitoring the current in a parallel resistor and a circuit for sensing an abrupt change in the output of the current shunt monitor; a power supply; a two-wire electrical conduit extending between the remote circuit and the two-wire adapter circuit and connecting the power supply to the voltage regulator of the remote circuit via said resistor in parallel with the current shunt monitor of the two-wire adapter circuit; and the sensing circuit in the remote circuit switching the output of the voltage regulator to a shunt resistor to place an additional drain on the voltage regulator upon detection of a sensed condition, said circuit for sensing the abrupt change in the output of the current shunt monitor due to the additional drain on the voltage regulator configured to output a defined digital signal on sensing the abrupt change.