Variable gain amplifier system utilizing a solid electroluminescent cell

Claim 1

A NETWORK HAVING ITS GAIN CONTROLLED IN RESPONSE TO THE AMPLITUDE OF AN INPUT SIGNAL SOURCE APPLIED THERETO COMPRISING A CONSTANT, PREDETERMINED GAIN AMPLIFIER HAVING THE INPUT TERMINALS THEREOF RESPONSIVE TO SAID SIGNAL SOURCE FOR DERIVING AN OUTPUT THAT IS A REPLICA OF THE SIGNAL AT SAID INPUT TERMINALS, A SOLID ELECTROLUMINESCENT LIGHT SOURCE COUPLED TO THE AMPLIFIER OUTPUT AND RESPONSIVE TO A VOLTAGE THAT IS A REPLICA OF THE AMPLIFIER OUTPUT, THE LIGHT INTENSITY DERIVING FROM SAID LIGHT SOURCE BEING SUBSTANTIALLY LINEARLY RELATED TO THE AMPLITUDE OF THE VOLTAGE APPLIED THERETO AND RESPONDING SUBSTANTIALLY SIMULTANEOUSLY TO THE VARIATIONS IN THE AMPLITUDE OF THE VOLTAGES APPLIED THERETO, AN ATTENUATING NETWORK CONNECTED TO SAID INPUT TERMINALS FOR COUPLING THE SIGNAL OF SAID SIGNAL SOURCE TO SAID INPUT TERMINALS, SAID ATTENUATING NETWORK INCLUDING A PHOTOCONDUCTIVE RESISTIVE ELEMENT OPTICALLY COUPLED TO BE RESPONSIVE TO THE LIGHT DERIVING FROM SAID LIGHT SOURCE.