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4041408 |
Push-pull audio amplifier system with muting
Audio signals are equally power divided with the power divided signals being 180° out-of-phase. These separate out-of-phase signals are separately applied to the inverting input of separate...
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3970804 |
Electro-mechanical amplifier sound transducer
This invention describes an electromechanical amplifying sound transducer including a diaphragm which responds to input energy, such as acoustical waves and mechanical pulses, and vibrates in...
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3968435 |
Communication system
An electronic short range communication system which allows communication between two or more parties who are fairly close to each other and which allows communication between parties having the...
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3946156 |
Adapter for recording-reproducing machine
The adapter is for insertion into a conventional recording-reproducing machine, is in the form of a tape cassette, and is for adapting the machine for use as part of a public address system. A...
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3944944 |
Power amplifier with distortion control
An electrical audio power amplifier is connected to receive an input informational signal from a pre-amplifying stage functioning with a transducer or pick-up device such as a magnetic phono...
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3944756 |
Electret microphone
An electret microphone having a head readily assembled within a housing in which an electrically conducting backplate and an air permeable filter member abut each other and form an electrical...
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3938057 |
Telecommunications signal amplifier
A telecommunications signal amplifier comprising an active tripole the transfer function of which has a negative real portion, the input impedance and the output impedance of which are...
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3930123 |
Sound communication system
A communication system for an emergency vehicle including a provision for selectively producing plural automatically and manually controlled siren sounds, the sound broadcast of radio reception and...
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3924070 |
Voice gated amplifier
A voice gated amplifier includes a multi-stage amplifier having a signal path coupling the successive stages of the amplifier. A normally nonconductive field effect transistor placed in series...
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3896274 |
Electret Earphone
A push-pull electrostatic transducer employs imperforate electret elements affixed to the surface of rigid vented backplates mounted on opposite sides of a conductive diaphragm.
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3881058 |
Convertible amplifier system for single and multiple signal sources
A convertible amplifier system includes a pair of operational amplifier means each having oppositely-phased input terminals, a pair of loudspeakers, and a switching means for selectively coupling...
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3862367 |
AMPLIFYING CIRCUIT FOR USE WITH A TRANSDUCER
An amplifying circuit for use with a transducer includes a pair of field-effect transistors which are of different conductive types from each other and each of which has gate, drain and source...
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3860755 |
NOVEL PORTABLE AMPLIFIER AND SPEAKER
A portable amplifier is described which comprises a housing having two pivotally interconnected or hinged housing sections. One housing subsection contains a speaker and electrical input jack or...
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3829625 |
SHUNT NEGATIVE IMPEDANCE AMPLIFIER
A transmission line isolation and amplifier circuit is disclosed having a negative impedance line isolator and an amplifier with a common input/output port therebetween. First and second resistive...
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3733441 |
AMBIPOLAR MICROPHONE UNIT
A microphone unit for incorporation in a telephone headset or the like including a low signal output transducer, and a polarity independent current control amplifier circuit for amplifying the...
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3729588 |
TRANSISTORIZED AMPLIFIER
The present invention relates to a transistorized audio amplifier especially for hearing aid equipment having an input stage and an output stage with a sound reproducer in the output stage between...
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3706852 |
QUIET TURN-ON CIRCUIT FOR CARBON MICROPHONES
A preamplifier for a carbon microphone is provided at its input with a field effect transistor biased to a non-conductive state. When the microphone switch is turned on to connect the microphone to...
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3701862 |
BATTERY HOLDER AND THREE-POSITION SWITCH FOR HEARING AID UNIT
A hearing aid switch of the type shown in U.S. Pat. No. 3,475,566 issued Oct. 28, 1969, is provided with additional contact position to add an additional mode of operation without increasing the...
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3694764 |
HIGH POWER AUDIO AMPLIFIER SYSTEM
The invention disclosed is for a new high power transistorized audio amplifier having a circuit characterized by high efficiency, and light weight resulting from a bridge configuration of power...
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3684830 |
AMPLIFIER MOUNTED ON ROTOR OF GAIN CONTROL DEVICE
The present invention relates to amplifying arrangements of sub-miniature construction which are provided with means for varying the gain of the amplifier. In particular, though not exclusively,...
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3683112 |
TEMPERATURE COMPENSATED AMPLIFIER EMPLOYING COMPLEMENTARY PAIRS OF TRANSISTORS
An amplifier including a first transistor and second and third transistors forming a complementary pair. The first and second transistors are of the same type. An input signal is applied to the...
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3668320 |
CONNECTION ARRANGEMENT FOR A TELEPHONE MICROPHONE AMPLIFIER WITH POWER SUPPLY CONNECTED TO THE OUTPUT SIDE OF THE AMPLIFIER
A speech amplifier for telephone microphones including an input direct coupled, differential amplifier, and an output Darlington-connected amplifier, with the operating points stabilized by...
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3659056 |
HEARING AID SYSTEMS
This invention relates to a hearing aid system for the education of deaf children, and permits the incorporation of such children in a class of normal children. The child carries a conventional...
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3651266 |
AN AMPLIFYING SYSTEM WITH REDUCED FEEDBACK
An amplifying system, particularly for application in which the input and output transducers are closely coupled acoustically, for example, hand-held power megaphones and the like, as a result of...
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3636281 |
LOUDSPEAKER USING WALL AS DIAPHRAGM
An electroacoustic transducer including a drive coil mounted within the airgap of an annular permanent magnet. The drive coil is connected to the transducer case which in turn is attached to a...
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3629522 |
HEADPIECE LOUDSPEAKER
A headpiece loudspeaker is disclosed herein having a headpiece incorporating a loudspeaker oriented so as to propagate acoustical energy from opposite sides of the headpiece. The side lobe...
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3624315 |
TRANSDUCER APPARATUS AND TRANSDUCER AMPLIFIER SYSTEM UTILIZING INSULATED GATE SEMICONDUCTOR FIELD EFFECT DEVICES
A transducer apparatus wherein the source to drain conductance of an insulated gate semiconductor field effect device is modulated by the application of mechanical stress to the channel layer of...
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3595998 |
POLARITY INDEPENDENT PREAMPLIFIER FOR SOUND TRANSMITTERS
A preamplifier for sound transmitters includes at least one field effect transistor having a gate electrode and first and second output electrodes. An output circuit is connected across the output...
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3586791 |
METHOD AND APPARATUS FOR HEARING BY BIODETECTION AND BIOTRANSDUCTION OF RADIOFREQUENCY ENERGY
The present invention relates to a method and apparatus utilizing R-F carriers of predetermined frequencies to stimulate the sensation of hearing in human subjects and, more particularly, to a...
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3571514 |
HEARING AID TONE CONTROL
A tone control circuit for a transistorized hearing aid amplifier comprising a transistor amplifier stage with an electromagnetic hearing aid microphone connected to its input. The output has a...
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3542953 |
AMPLIFIERS POWERED FROM A SINGLE POWER SUPPLY AND DRIVEN CONTRAPHASALLY
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3529085 |
POD AUDIO SYSTEM
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3525810 |
MICROPHONE ASSEMBLY FOR USE IN A STETHOSCOPE
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3514539 |
PORTABLE SOUND SYSTEM
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3513465 |
SOUND MONITORING SYSTEM HAVING PLURAL SELECTIVELY DISCONNECTABLE MICROPHONES AND A CENTRAL MONITORING STATION
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3499988 |
LOUDSPEAKER APPARATUS WITH AUDIO FREQUENCY AMPLIFIER MOUNTED THEREON
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3496297 |
SOUND AMPLIFYING APPARATUS
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3492585 |
BATTERY-OPERATED AUDIO SYSTEM HAVING MEANS FOR PROVIDING REDUCED BATTERY CURRENT DRAIN
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3491203 |
TEMPERATURE STABILIZED AMPLIFIER
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3483324 |
SOUND PICKUP
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3479576 |
SUPERCONDUCTING AMPLIFIER
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3437756 |
AUDIO AMPLIFIER PRODUCING HIGH FIDELITY SOUND REPRODUCTION
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3414675 |
TELEPHONE HANDSET WITH PRESSURE GRADIENT MICROPHONE SUBSTITUTED FOR CARBON MICROPHONE
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3372342 |
Differential power amplifier
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3370125 |
Auxiliary loud-speaker system
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3368551 |
Method for correcting subvocalization
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3363060 |
Overload protected transistor amplifier
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3320365 |
Self-biasing amplifier
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3317671 |
Electrical amplifier with input circuit direct-current-limiting means
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3300585 |
Self-polarized electrostatic microphone-semiconductor amplifier combination
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