Electrically operated audible alarm

Claim 1

AN ALERTING DEVICE COMPRISING A PIEZOELECTRIC TRANSDUCER HAVING A VIBRATORY SURFACE FROM WHICH ACOUSTIC ENERGY IS RADIATED A PIEZOELECTRIC MEANS OPERATIVE TO DRIVE SAID SURFACE, SAID TRANSDUCER HAVING A PREDETERMINED FREQUENCY OF RESONANCE AND OPERABLE, WHEN VIBRATING SUBSTANTIALLY AT SAID FREQUENCY, TO RADIATE SUBSTANTIAL AUDIBLE SOUND ENERGY SUBSTANTIALLY WITHIN THE FREQUENCY RANGE OF THE EAR''S MAXIMUM SENSITIVITY, A CIRCUIT FOR ENERGIZING SAID PIEZOELECTRIC MEANS, SIAD CIRCUIT INCLUDING AMPLITUDE MEANS WITH A TRANSISTOR ACTUATOR, MEANS FOR CONDUCTING ENERGY FROM SAID AMPLIFIER TO SAID PIEZOELECTRIC MEANS, A FEEDBACK PATH FROM SAID PIEZOELECTRIC MEANS TO SAID AMPLIFIER, THE CIRCUIT INCLUDING MEANS TO PROVIDE PHASING, BIASING, AND IMPEDANCE MATCHING TO PROVIDE AN OSCILLATOR WHEREBY THE ENERGY INPUT TO SAID PIEZOELECTRIC MEANS IS CAUSED TO OSCILLATE SUBSTANITALLY AT SAID RESONANT FREQUENCY OF SAID TRANSDUCER TO PROVIDE AN AUDIBLE WARNING.