Sonic testing decay detector

Claim 1

IN TESTING MEANS FOR CHECKING THE SOUNDNESS OF PARTS HAVING A NATURAL RESONANT FREQUENCY OF VIBRATION, MEANS TO STRIKE A PART TO BE TESTED TO SET IT INTO RESONANT VIBRATION, TRANSDUCER MEANS MOUNTED ADJACENT SAID PART WHEN IN ITS VIBRATORY STATE TO PICK UP THE MECHANICAL VIBRATONS OF THE SAME AND CONVERT THEM INTO ELECTRICAL OSCILLATIONS, AMPLIFYING MEANS CONNECTED TO THE TRANSDUCER MEANS TO AMPLIFY THE ELECTRICAL OSCILLATIONS PRODUCED BY THE TRANSDUCER MEANS, RECTIFIER MEANS CONNECTED TO THE AMPLIFYING MEANS TO PROVIDE A DIRECT CURRENT VOLTAGE FROM THE SIGNAL OUTPUT OF THE AMPLIFYING MEANS, A PLURALITY OF PARALLEL CIRCUITS CONNECTED TO THE OUTPUT OF THE RECTIFIER MEANS EACH INCLUDING ADJUSTABLE IMPEDANCE MEANS ACROSS WHICH THE DIRECT CURRENT VOLTAGE IS DEVELOPED, A SOURCE OF ELECTRICAL POWER, ELECTRONIC MEANS HAVING A CONTROL ELECTRODE CONNECTED TO EACH ADJUSTABLE IMPEDANCE MEANS AND SET TO CONDUCT AT DIFFERENT VALUES, A FIRST SWITCHING MEANS CONNECTED BETWEEN THE SOURCE OF ELECTRICAL POWER AND THE ELECTRONIC MEANS TO CONTROL THE INITIAL ENERGIZATION THEREOF, RELAY SWITCHING MEANS CONNECTED TO EACH ELECTRONIC MEANS AND ACTUATED BY CONDUCTION THROUGH THE SAME AND TIMING MEANS CONNECTED TO THE SOURCE OF ELECTRICAL POWER AND THE RELAY SWITCNING MEANS AND TURNED ON AND OFF THEREBY TO INDICATE THE DURATION OF THE TIME OF DECAY OF THE AMPLITUDE OF THE SIGNAL FROM ONE VALUE TO ANOTHER AS INDICATION OF THE SOUNDNESS OF THE PART.