Vxi Corporation

David J Truesdell

Costas Papadopoulos

Costas Papopoulos

Daniel S Davidson

Victor J Temple

A microphone system including a microphone for inputting voice data, an output for transmitting the voice data to a device connectable thereto; and a circuit which operates to mute the voice data and provide a signal to the device in order to maintain a suspended state of operation in the device. The device may be a computer that is responsive to voice data, for example, by utilizing voice recognition software.

Microphone circuit with mute and keep alive function

A circuit for connecting an electret microphone to audio inputs. The circuit includes a coupling circuit for accepting DC bias voltage from the audio inputs and providing audio signal to the inputs. Frequency shaping circuitry is provided for reducing unwanted microphone sensitivity at selected frequencies. In one aspect of the invention a battery connector is provided where at least one battery may be optionally connected.

Amplifier circuit for electret microphone with enhanced performance

An electret microphone circuit including an electret microphone having a field effect transistor (FET) with a gate coupled to an electret diaphragm, a drain coupled to provide audio frequency output to an audio output node, a source terminal coupled to ground, and an amplifier stage with an RLC circuit coupled to the drain for configuring the audio frequency output to desired characteristics and for obtaining microphone bias from the output node. The amplifier stage can comprise discrete transistors or integrated operational amplifiers. In another embodiment of the invention there is provided a transistor with a drain coupled to provide audio frequency output to an audio output node and for obtaining microphone bias am from said output node, a source terminal coupled to the microphone housing, and an NPN transistor current mirror stage with an RC or RLC circuit coupled to the source for configuring the audio frequency output to desired characteristics. In yet another embodiment of the invention there is provided a transistor with a source terminal coupled to ground, and an PNP transistor current mirror stage with an RC or RLC circuit coupled to the drain for configuring the audio frequency output to desired characteristics and for obtaining microphone bias from the output node. In one aspect of the invention, the PNP current mirror with RLC circuit is provided with means for adding batteries optionally and is followed by a diode and capacitor coupling network to accept bias current optimally from the output node.

A battery circuit for coupling a battery source to an electret microphone. The circuit includes impedance circuitry for providing appropriate bias impedance for a desired microphone sensitivity, and disconnect circuitry for automatically disconnecting the battery source from the electret microphone in response to detecting a low voltage state in order to prevent distortion and low output level of the microphone. In an alternative embodiment of the invention there is provided second impedance circuitry for driving corresponding inputs with minimal loss. In another alternative embodiment of the invention there is provided a compensation circuit which operates to extend battery source life and prevent lower output at lower voltage.

Electret microphone circuit with low battery disable

A computer telephony system including a telephone communication unit operable for initiating and receiving voice calls and a computer operable for providing and receiving voice data. Circuitry is provided for coupling voice data between the computer and the telephone communication unit simultaneously with the voice calls, and for isolating the voice data from the voice calls. In another embodiment of the invention, there is provided a computer telephony amplifier for use with a telephone communication unit operable for initiating and receiving voice calls and a computer operable for providing and receiving voice data. The amplifier includes circuitry for transmitting and receiving voice data between the computer and the telephone communication unit simultaneously with the voice calls, and for isolating the voice data from the voice calls.

Computer telephony headset amplifier

A telephone headset interface circuit is coupled to a telephone line to extract power for use by a headset amplifier and is particularly adapted for use with telephone handsets having dynamic or electret microphones. The telephone line connects a telephone to a service system, such as a Central Office, a PBX system, or a Key system. The interface circuit includes a power extraction circuit having a plurality of circuit portions, each one coupled to a corresponding one of the telephone line wires for providing a predetermined output voltage, so that substantially identical electrical impedance characteristics are introduced to each such wire. An amplifier is coupled to the telephone handset such that the predetermined constant output voltage is coupled to the amplifier to power the amplifier from the telephone line when the telephone includes an electronic microphone handset. An isolated rectifier circuit powers the amplifier when the telephone includes another handset other than an electronic microphone handset, such as a carbon microphone handset or a DC powered handset.

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Acton, MA, United States of America

David J Truesdell