Traffic loop detector

Claim 1

MEANS FOR DETECTING THE MOVEMENT OF VEHICLES AND THE LIKE COMPRISING FIRST MEANS ARRANGED FOR INDUCTIVE ASSOCIATION WITH MOVING VEHICLE; SECOND MEANS FOR FORMING A RESONANT ELECTRICAL CIRCUIT WITH SAID FIRST MEANS; THIRD TRANSISTOR MEANS FOR SUPPLYING ENERGY TO SAID FIRST AND SECOND MEANS; FEEDBACK MEANS COUPLED TO SAID THIRD MEANS FOR SUSTAINING THE OPERATION OF SAID FIRST, SECOND, AND THIRD MEANS AT THE RESONANT FREQUENCY; FOURTH MEANS FOR DEMODULATING THE OUTPUT OF THE RESONANT CIRCUIT TO PRODUCE THE WAVE ENVELOPE OF SAID FREQUENCY SIGNAL; THE RATE OF DISSIPATION OF ENERGY BY SAID RESONANT CIRCUIT BEING INCREASED DUE TO THE PASSAGE OF A VEHICLE; VARIABLE IMPEDANCE MEANS CONNECTED IN SERIES WITH SAID THIRD TRANSISTOR MEANS TO REDUCE THE OUTPUT OF SAID THIRD MEANS WHEN ITS ENERGY DISSIPATION RATE INCREASES; SAID VARIABLE IMPEDANCE MEANS COMPRISING FIFTH TRANSISTOR MEANS HAVING BASE, EMITTER AND COLLECTOR ELECTRODES; SIXTH MEANS FOR MAINTAINING SAID BASE ELECTRODE AT A REFERENCE VOLTAGE LEVEL; RESISTANCE MEANS COUPLED IN PARALLEL ACROSS SAID EMITTER AND COLLECTOR ELECTRODES; ONE TERMINAL OF SAID RESISTANCE MEANS BEING CONNECTED TO SAID THIRD TRANSISTOR AMPLIFIER MEANS, AND THE OTHER TERMINAL OF SAID RESISTANCE MEANS BEING COUPLED TO GROUND POTENTIAL.