Abstract: An audio signalling device provides a housing having at least one end, a piezoelectric transducer, a nodal mounting for the piezoelectric transducer in proximity to the end of the housing, a planar member, a mounting for the planar member in a spaced adjacent relationship with the piezoelectric transducer, and spring contacts mounted on the planar member for making spring biased electrical contact with the piezoelectric transducer.

Abstract: A circular diaphragm typically edge mounted to the housing of an electroacoustic transducer includes a plurality of inwardly curved slots isolated by a circular ridge formed in the diaphragm to thereby increase the compliance of the diaphragm at the center of the circular ridge. Portions of the slots are overlapped to maintain a substantially rectangular section of the diaphragm between the slots. The slotting and rectangular sections of the diaphragm allow the center of the circular ridge to flex in a piston-like manner whereby higher frequency flexural modes of the diaphragm are either reduced or completely eliminated.

Abstract: A multiple tone signaling device provides a piezoelectric transducer, first, second and third oscillator circuits, a first input terminal for enabling either or both of the first and second oscillator circuits, circuitry coupling the third oscillator circuit to the first and second oscillator circuits for disabling either the first or second oscillator circuits in response thereto, and a second input terminal coupled to the third oscillator circuit for allowing control of the output of said third oscillator circuit.

Abstract: An audible signalling system utilizes a piezoelectric transducer to produce a chime tone audible signal. The system includes audible signalling circuitry, circuitry for driving the audible signalling circuitry to provide a pulsed audible signal, and circuitry for exponentially decaying the pulsed audible signal to produce a chime tone audible signal.

Abstract: The resonant frequency of a conventional piezoelectric transducer having predetermined dimensions and a fundamental nodal diameter is reduced while maintaining the overall predetermined diameter and fundamental nodal diameter of the transducer. A method of reducing the resonant frequency of a conventional piezoelectric transducer includes the step of radially slotting the substrate of the transducer.

Abstract: A buzzer alarm has an electrically insulative housing fabricated of two molded pieces of electrically insulative material with a recessed vibratable diaphragm section constructed as a portion thereof. The buzzer alarm includes cooperating vibrating means and timer means with the vibrating means being carried by a frame that is carried along a wall which is complimentary to another wall which carries a terminal block.

Abstract: The electroacoustical properties of an electromechanical vibrating device for producing an audible signal are improved by attenuating undesirable frequencies of the audible signal to produce a predominant frequency and by accentuating the predominant frequency. The improvement includes a planar vibration diaphram comprised of a plastic polymer material, a vibrating striking member positioned to strike the vibration diaphram at its center; a bumper comprised of resilient material interposed between the vibrating striking member and the vibration diaphram, and a resonant chamber in spaced relation to the vibration diaphram having a resonant frequency substantially equal to the predominant frequency.

Abstract: A piezoelectric transducer and a voltage doubling means are utilized in conjunction with a power supply means, a pulsator means, an amplifier means, and an acoustical loading means to produce an efficient high output audible alarm device. The voltage doubling means and the acoustical loading means enhance the audible output of the alarm device while increasing the overall electroacoustical efficiency of the alarm.

Abstract: A high output smoke and heat detector alarm system comprises a high output audible alarm means which includes a piezoelectric transducer and a voltage doubling means in combination with an improved smoke and heat detector which includes a low voltage power supply source, an ambient temperature detecting means, at least one ionization sensing chamber, a voltage amplitude comparing means, and a low voltage sensing means.

Abstract: A high output smoke and heat detector alarm system comprises a high output audible alarm means which includes a piezoelectric transducer and a voltage doubling means in combination with an improved smoke and heat detector which includes a low voltage power supply source, an ambient temperature detecting means, at least one ionization sensing chamber, a voltage amplitude comparing means, and a low voltage sensing means.