Feedback controlled sonic liquid detector

Claim 1

APPARATUS FOR DISTINGUISHING BETWEEN THE PRESENCE OF LIQUID AND AIR INCLUDING A FEEDBACK CONTROLLED OSCILLAFOR CIRCUIT HAVING AN INPUT AND AN OUTPUT, A POWER SUPPLY OPERATIVELY INTERCONNMECTED WITH THE OSCIALLATOR CIRCUIT, A POSITIVE FEEDBACK CIRCUIT CONNECTING THE OUTPUT AND INPUT OF THE OSCILLATOR CIRCUIT AND EFFECTIVE TO TRANSMIT A FEED BACK SIGNAL THEREBETWEEN, THE POSITIVE FEEDBACK CIRCUIT INCLUDING FIRST AND SECOND SONIC TRANSDUCERS SPACED A PREDETERMINED DISTANCE APART IN A VOLUME NORMALLY ACCUPIED BY LIQUID AND MUTUALLY COUPLED IN ENERGY TRANSFER RELATION THROUGH A PREDETERMINED TRANSMISSION PATH, THE FIRST AND SECOND TRANSDUCERS HAVING A FIRST ELECTROMECHANICALLY RESONANT FREQUENCY WHEN THE TRANSDUCERS ARE IN CONTACT WITH A LIQUID AND A SECOND ELECTROMECHANICALLY RESONANT FREQUENCY WHEN THEY ARE IN CONTACT WITH AIR, REACTIVE MEANS CONNECTED IN CIRCUIT WITH THE FIRST TRANSDUCER FOR TUNING THE COMBINATION OF THE REACTIVE MEANS AND THE EQUAL TO THE FIRST ELECTROMECHANICALLY RESONA FREQUENCY EQUAL TO THE FIRST ELECTROMECHANICALLY RESONANT FREQUENCY, WHEREBY THE FEEDBACK SIGNAL IS OF A FIRST MAGNITUDE WHEN THE TRANSDUCERS ARE IN CONTACT WITH LIQUID AND A SECOND MAGNITUDE WHEN THE TRANSDUCERS ARE IN CONTACT WITH AIR, THE REACTIVE MEANS BEING EFFECTIVE TO SHIFT THE FEEDBACK SIGNAL IN PHASE BYY A FIRST ANOUNT, THE PREDETERMINED TRANSMISSION PATH BEING EFFECTIVE TO SHIFT THE FEEDBACK SIGNAL IN PHASE BY SECOND AND THIRD AMOUNTS CORRESPONDING TO THE PRESENCE OF LIQUID AND AIR, RESPECTIVELY, IN THE TRANSMISSION PATH, THE FEEDBACK SIGNAL BEING EFFECTIVE TO PRODUCE AN OSCILLATORY OUTPUT OF A FIRST AMPLITUDE FROM THE OSCILLATOR CIRCUIT WHEN THE FEED BACK SIGNAL IS OF THE FIST MAGNITUDE AND IS SHIFTED IN PHASE BY THE SUM OF THE FIRST AND SECOND AMOUNTS, AND A SECOND AMPLITUDE WHEN THE FEEDBACK SIGNAL IS OF THE SECOND MAGNITUDE AND IS SHIFTED IN PHASE BY THE SUM OF THE FIRST AND THIRD AMOUNTS, AND INDICATOR MEANS CONNECTED TO THE OUTPUT OF THE OSCILLATOR CIRCUIT AND ADAPTED TO INDICATE WHETHER THE OSCILLATORY OUTPUT IS OF THE FISRST OR SECOND AMPLITUDES.