High sensitivity voltage monitor

Claim 1

A VOLTAGE MONITORING CIRCUIT COMPRISING FIRST AND SECOND TRANSISTORS EACH HAVING BASE, COLLECTOR, AND EMITTER ELECTRODES, FIRST VOLTAGE SAMPLING MEANS FOR APPLYING A FIRST PREDETERMINED PORTION OF THE VOLTAGE TO BE MONITORED TO THE BASE ELECTRODE OF SAID FIRST TRANSISTOR, SECOND VOLTAGE SAMPLING MEANS FOR APPLYING A SECOND PREDETERMINED PORTION OF THE VOLTAGE TO BE MONITORED TO THE BASE ELECTRODE OF SAID SECOND TRANSISTOR, A SOURCE OF REFERENCE VOLTAGE, MEANS CONNECTING SAID SOURCE OF REFERENCE VOLTAGE TO THE EMITTER ELECTRODES OF EACH OF SAID FIRST AND SECOND TRANSISTORS, AN INDICATOR CONNECTED TO THE COLLECTOR ELECTRODE OF SAID FIRST TRANSISTOR TO REGISTER AN EXCURSION OF THE VOLTAGE AT THE BASE ELECTRODE OF SAID FIRST TRANSISTOR TO A MAGNITUDE LESS THAN THE MAGNITUDE OF SAID REFERENCE VOLTAGE, AND MEANS CONNECTING THE COLECTOR ELECTRODE OF SAID SECOND TRANSISTOR TO THE BASE ELECTRODE OF SAID FIRST TRANSISTOR CAUSE THE BIAS AT THE BASE ELECTRODE OF SAID FIRST TRANSISTOR TO BE REDUCED WHEN AN EXCURSION OF THE VOLTAGE BEING MONITORED INCREASES THE VOLTAGE AT THE BASE ELECTRODE OF SAID SECOND TRANSISTOR TO A MAGNITUDE GREATER THAN THE MAGNITUDE OF SAID REFERENCE VOLTAGE, WHEREBY SAID INDICATING MEANS REGISTERS AN ABNORMAL VOLTAGE CONDITION WHENEVER THE MAGNITUDE OF THE FIRST PREDETERMINED PORTION OF THE MONITORED VOLTAGE FALLS BELOW THE MAGNITUDE OF THE REFERENCE VOLTAGE OR THE MAGNITUDE OF THE SECOND PREDETERMINED PORTION OF THE MONITORED VOLTAGE EXCEEDS THE MAGNITUDE OF THE REFERENCE VOLTAGE.