Alarm system

Claim 1

AN ELECTRICAL PROTECTION SYSTEM FOR DETECTING PHYSICAL ATTACKS ON VAULTS AND LIKE STRUCTURES, COMPRISING AT LEAST ONE VIBRATION TRANSDUCER MOUNTED IN CLOSE PHYSICAL CONTACT WITH AN INTERIOR SURFACE OF SAID STRUCTURE AND INCLUDING A VIBRATION DETECTING ELEMENT ARRANGED TO PRODUCE AN ALTERNATING SIGNAL VOLTAGE IN RESPONSE TO DETECTION OF VIBRATIONS TRANSFERRED TO SAID DETECTING ELEMENT FROM SAID SURFACE, SAID VIBRATION TRANSDUCER BEING RELATIVELY INSENSITIVE TO AIRBORNE VIBRATIONS IN THE SPACE WITHIN SAID STRUCTURE, AN AMPLIFIER HAVING AN INPUT CIRCUIT COUPLED TO SAID DETECTING ELEMENT, AN ELECTRONIC SWITCH ELEMENT HAVING AN INPUT CIRCUIT COUPLED TO THE OUTPUT CIRCUIT OF SAID AMPLIFIER AND BEING ARRANGED TO TRANSFER FROM ONE CONDUCTION CONDITION TO ANOTHER CONDUCTION CONDITION WHEN THE AMPLIFIED SIGNAL VOLTAGE OUTPUT OF SAID AMPLIFIER EXCEEDS A PREDETERMINED VALUE, A FIRST RELAY MEANS HAVING A COIL INCLUDED IN THE OUTPUT CIRCUIT OF SAID ELECTRONIC SWITCH ELEMENT AND ARRANGED TO TRANSFER BETWEEN ITS ENERGIZED AND NONENERGIZED STATES UPON TRANSFER OF SAID ELECTRONIC SWITCH ELEMENT FROM SAID ONE CONDUCTION CONDITION THEREOF TO SAID OTHER CONDUCTION CONDITION THEREOF, A CAPACITIVE ELEMENT, A CHARGING CIRCUIT FOR SAID CAPACITIVE ELEMENT INCLUDING A SOURCE OF POTENTIAL OF FIXED MAGNITUED AND CONTACTS CONTROLLED BY SAID FIRST RELAY MEANS AND ARRANGED TO BE CLOSED UPON SAID TRANSFER OF STATE OF SAID FIRST RELAY MEANS THEREBY TO CHARGE SAID CAPACITIVE ELEMENT TOWARD SAID POTENTIAL WHILE THE OUTPUT OF SAID AMPLIFIER EXCEEDS SAID PREDETERMINED VALUE, A DISCHARGING CIRCUIT COUPLED TO SAID CAPACITIVE ELEMENT AND HAVING A TIME CONSTANT SUBSTANTIALLY GREATER THAN THE TIME CONSTANT OF SAID CHARGING CIRCUIT, AN UNIJUNCTION TRANSISTOR HAVING THE RESPECTIVE BASES THEREOF COUPLED TO A SOURCE OF OPERATING POTENTIAL, A SECOND RELAY MEANS HAVING THE COIL THEREOF INTERCOUPLING THE EMITTER OF SAID UNIJUNCTION TRANSISTOR AND SAID CAPACITIVE ELEMENT WHEREBY SAID UNIJUNCTION TRANSISTOR WILL BECOME CONDUCTIVE WHEN THE CHARGE ACROSS SAID CAPACITOR EXCEEDS A PREDETERMINED LEVEL, SAID SECOND RELAY MEANS BECOMING ENERGIZED WHEN SAID UNIJUNCTION TRANSISTOR BECOMES CONDUCTIVE, AND MEANS INCLUDING CONTACTS OF SAID SECOND RELAY MEANS TO PRODUCE AN ALARM SIGNAL WHEN SAID UNIJUNCTION TRANSISTOR IS CONDUCTIVE.