Tone ringer with a negative impedance amplifier

Claim 3

A device as claimed in claim 1, characterized in that the amplifier includes two transistors and circuit connection means for cross-coupling the base and the collector of one transistor to the collector and the base, respectively, of the other transistor.

Claim 4

A device as claimed in claim 1, characterized in that the transistors are of the same conductivity type.

Claim 5

A device as claimed in claim 1 wherein the electrical impedance of the electro-acoustic converter is connected in the collector circuit of one of the transistors.

Claim 6

A device as claimed in claim 1 wherein the electroacoustic converter is designed to have an impedance-frequency characteristic approximately of the form shown in FIG. 3.

Claim 7

An electroacoustic oscillator circuit for converting ringing signals of a first frequency into acoustic power of a second frequency comprising, a pair of input terminals adapted to receive the ringing signals, a non-selfoscillating two-port regenerative feedback amplifier, a supply device coupled between the input terminals and the amplifier for converting the ringing signals into a supply voltage for the amplifier, an electroacoustic converter whose impedance varies with frequency and including an acoustic resonator and only two electric terminals, means directly connecting the two terminals of the electroacoustic converter to respective ports of said amplifier, said electroacoustic converter being designed to have an impedance variation as a function of frequency such that the oscillator circuit will oscillate at the frequency at which the absolute value of the electric impedance of the electro-acoustic converter is a maximum.

Claim 8

An electroacoustic oscillator circuit for converting ringing signals of a first frequency into acoustic power of a second frequency comprising, a pair of input terminals adapted to receive the ringing signals, a non-selfoscillating two-port regenerative feedback amplifier, a supply device coupled between the input terminals and the amplifier for converting the ringing signals into a supply voltage for the amplifier, an electroacoustic converter whose impedance varies with frequency and including an acoustic resonator and only two electric terminals, means directly connecting the two terminals of the electroacoustic converter to respective ports of said amplifier, said electroacoustic converter being designed to have an impedance variation as a function of frequency such that the oscillator circuit will oscillate at the frequency at which the absolute value of the electric impedance of the electro-acoustic converter is a maximum.

Claim 9

An oscillator as claimed in claim 6 wherein the amplifier comprises first and second transistors with circuit means cross-connecting the base and collector of one transistor to the collector and base, respectively, of the other transistor to form a bistable operating device.

Claim 10

An oscillator as claimed in claim 6 wherein the circuit elements constituting the two-port amplifier include only resistors and other substantially non-reactance elements whereby the electroacoustic converter solely determines the oscillation frequency of the oscillator.

Claim 11

An oscillator as claimed in claim 6 wherein the electroacoustic converter comprises, a cylindrical housing, a diaphragm secured to the inner wall of the cylinder to divide same into an upper part and a lower part, an apertured magnetic core with a winding mounted thereon and secured in the upper part of the cylinder, an apertured partition member secured to the inner wall of the cylinder so as to divide the lower part of the cylinder into two cavities that communicate with each other via the aperture in the partition member, means for closing the upper end of the cylinder, and means providing an aperture in the cylinder wall by which the outside air communicates with the lower of said two cavities.

Claim 12

An electroacoustic converter system for converting an AC electric ringing signal into an acoustic signal comprising, a pair of input terminals adapted to receive the AC ringing signal, a two-port negative impedance device including a positive feedback amplifier devoid of reactive tuning elements and exhibiting a negative impedance between its two ports, supply means coupled between the input terminals and the negative impedance device for converting an AC ringing signals received into a DC supply voltage for the amplifier, an electroacoustic transducer exhibiting a resonant frequency and having two electric terminals directly connected to the two ports of the negative impedance device, said transducer being operative to be the sole control of the ringing frequency of the converter system upon receipt of an electric ringing signal at said input terminals whereby the system automatically oscillates at the transducer resonant frequency.

Claim 13

An electroacoustic converter system for converting an AC electric ringing signal into an acoustic signal comprising, a pair of input terminals adapted to receive the AC ringing signal, a two-port negative impedance device including a positive feedback amplifier devoid of reactive tuning elements and exhibiting a negative impedance between its two ports, supply means coupled between the input terminals and the negative impedance device for converting an AC ringing signals received into a DC supply voltage for the amplifier, an electroacoustic transducer exhibiting a resonant frequency and having two electric terminals directly connected to the two ports of the negative impedance device, said transducer being operative to be the sole control of the ringing frequency of the converter system upon receipt of an electric ringing signal at said input terminals whereby the system automatically oscillates at the transducer resonant frequency.

Claim 14

A converter system as claimed in claim 10 wherein said amplifier includes only resistive passive circuit elements and a transistor connected thereto so as to operate the transistor in a switching mode between cut-off and saturation states.