Gain-adjusting audio level terminator

Claim 1

IN A TERMINATOR OF THE TYPE DESIGNED FOR APPLICATION IN A COMMUNICATION SYSTEM TO CONNECT A TERMINAL FACILITY TO THE RECEIVING AND TRANSMITTING CHANNEL OF SAID SYSTEM, THE COMBINATION, WITH A COMMON POWER SUPPLY, OF: A RECEIVING AMPLIFIER INCLUDING A SIGNAL-RECEIVING LINE; A TRANSMITTING AMPLIFIER INCLUDING A SIGNAL-TRANSMITTING LINE SAID AMPLIFIERS RESPECTIVELY INCLUDING AMPLIFIER CIRCUITS CONNECTED TO SAID LINES THEREOF; A CONNECTING CIRCUIT COMMON TO BOTH AMPLIFIERS AND INCLUDING INPUT AND OUTPUT LINES ADAPTED FOR COUPLING TO THE ASSOCIATED TERMINAL FACILITTY SO AS TO PROVIDE A PATH OF SIGNAL TRANSMISSION BETWEEN THE TERMINAL FACILITY AND THE RESPECTIVE AMPLIFIERS, SAID CONNECTING CIRCUIT INCLUDING MEANS EFFECTIVE UPON EACH OF SAID AMPLIFIERS TO AT LEAST PARTIALLY ISOLATE THE SAME FROM THE OTHER AMPLIFIER IN THE PRESENCE OF SIGNAL TRANSMISSION BETWEEN THE CONNECTING CIRCUIT AND SAID OTHER AMPLIFIER, THE AMPLIFIER CIRCUIT OF THE RECEIVING AMPLIFIER INCLUDING AN AMPLIFYING TRANSISTOR AND FURTHER INCLUDING RESISTOR MEANS CONNECTED BETWEEN THE BASE ELEMENT OF SAID TRANSISTOR AND SAID POWER SUPPLY, THE VALUE OF SAID RESISTOR MEANS BEING SELECTED TO NORMALLY MAINTAIN THE TRANSISTOR IN A PARTIALLY CONDUCTING AMPLIFYING CONDITION, SAID AMPLIFYING CIRCUIT OF THE RECEIVING AMPLIFER ADDITIONALLY INCLUDING A VARIABLE RESISTOR HAVING A CONNECTION WITH THE SIGNAL-RECEIVING LINE; A RECTIFIER CIRCUIT CONNECTED BETWEEN THE VARIABLE RESISTOR AND SAID COMMON POWER SUPPLY, SAID VARIABLE RESISTOR BEING MANUALLY SETTABLE IN SELECTIVE POSITIONS EFFECTIVE TO PERMIT THE PASSAGE THEREBY ONLY OF SIGNALS ABOVE A CORRESPONDINGLY SELECTED AUDIO LEVEL, SAID RECTIFIER CIRCUIT INCLUDING MEANS RESPONDING TO THE INPUT OF SIGNAL CURRENT THERETO FROM THE VARIABLE RESISTOR TO IMPRESS AMPLIFYING CURRENT THROUGH THE COMMON POWER SUPPLY UPON SAID TRANSISTOR AT A VALUE EFFECTIVE FOR TRANSITION OF THE TRANSISTOR TO A FULLY CONDUCTING STATUS; ATTENUATION MEANS FOR THE TRANSMITTING AMPLIFIER INCLUDING A RECTIFYING NETWORK CONNECTED BETWEEN THE RECTIFIER CIRCUIT AND THE AMPLIFYING CIRCUIT OF THE TRANSMITTING AMPLIFIER, AND ATTENUATING THE SIGNAL OF SAID AMPLIFIER CIRCUIT OF THE TRNSMITTING AMPLIFIER IN THE PRESENCE OF SIGNAL ENERGY IN THE RECEIVING AMPLIFIER OF A MAGNITUDE ABOVE SAID SELECTED AUDIO LEVEL; AND ATTENUATION MEANS FOR THE RECEIVING AMPLIFIER AND RECTIFIER CIRCUIT, INCLUDING A RECTIFYING NETWORK CONNECTED BETWEEN THE TRANSMITTING AMPLIFIER AND SAID RECEIVING AMPLIFIER AND RECTIFIER CIRCUIT, ARRANGED TO ATTENUATE THE SIGNAL OF THE RECEIVING AMPLIFIER AND RECTIFIER CIRCUIT IN THE PRESENCE OF SIGNAL ENERGY IN THE AMPLIFYING CIRCUIT OF THE TRANSMITTING AMPLIFIER, HAVING A VALUE ABOVE A PRESELECTED MINIMUM MAGNITUDE.