Abstract: A wireless audio system is provided that includes plurality of transmitters that digitizes and encrypts audio signals in compliance with a defined protocol standard. A plurality of listening apparatuses receive the audio signals and process the audio signals for listening within the listening apparatuses, wherein each transmitter is designated an identifier to facilitate selection and connection to one or more listening apparatuses with the desired transmitter simultaneously.

Abstract: A wireless audio system is provided that includes plurality of transmitters that digitizes and encrypts audio signals in compliance with a defined protocol standard. A plurality of listening apparatuses receive the audio signals and process the audio signals for listening within the listening apparatuses, wherein each transmitter is designated an identifier to facilitate selection and connection to one or more listening apparatuses with the desired transmitter simultaneously.

Abstract: A system and method for powering an ultraviolet (UV) water purification system utilizing a dynamo. A dynamo, operably attached to the UV water purification system, generates power from a rotatable crank which is actuated by a user around an axis of the rotatable crank. When the crank is rotated, the dynamo produces an electrical current that activates and powers the UV lamp, which in turn, produces UV light to purify the water. To ensure that the water has been purified appropriately, a microcontroller, employed within the UV water purification system, tracks both the “on” time and the intensity of the UV lamp as the dynamo is cranked. Once the lamp has been “on” at a sufficient intensity and for an appropriate period of time to administer a required dose of UV light, the microcontroller disables the lamp and provides the user with notification that the process has completed.

Abstract: A telephone line interface includes a ring detect circuit for activating a RF transceiver and thereby notifying the RF headset of a ringing condition on a telephone line. A wire conversion circuit separates transmit voice signals from receive voice signals and provides the separated voice signals to the RF transceiver. A firmware allows the electronic hook switch to go off hook only when the line is ringing or only when the line is off hook.

Abstract: An interface apparatus interposed between a cordless telephone base unit and a personal computer sound card. Such interface emulates a Central Office connection with respect to the telephone and a mic and speaker connection with respect to the computer sound card. The apparatus is suitable for all cordless telephones regardless of frequency allocation standards because the interface occurs at the RJ-11 modular jack of the cordless phone base, normally intended for connection to a CO line. Differences in telephone line regulations that exist among countries are accounted for with no burden of complexity to the user of the present invention. The interface comprises active and passive circuits perform two-wire-to-four-wire conversion and signal conditioning. Local loop current may be obtained from batteries or a suitable AC power adapter.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In one embodiment of the invention there is provided an electret microphone circuit including an electret microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source coupled to ground via a first resistor so as to reduce drain current swings; and an RLC circuit coupled to the drain for configuring the audio frequency output from the drain to desired characteristics. In an alternative embodiment there is provided a circuit coupled to said FET for operating said FET in a source follower mode so as to create low output impedance. In another embodiment of the invention there is provided a method of improving performance of an electret microphone, the microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source.

Abstract: 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, so that substantially identical electrical impedance characteristics are introduced to each such wire. A ring suppress circuit, serially coupled between the power extraction circuit and the headset amplifier, senses the presence of a ringing voltage on the telephone line and decouples the power extraction circuit from the amplifier in response thereto.

Abstract: 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.

Abstract: A radio-frequency detection apparatus including a signal input for providing an input signal and a phase shifter having a first connection and a second connection. The phase shifter includes a SAW device having a first electrical connection and a second electrical connection, wherein the SAW first electrical connection is coupled to the phase shifter first connection and the SAW second electrical connection is coupled to the phase shifter second connection. The radio-frequency detection apparatus also includes a multiplier having a multiplier first input connection, a multiplier second input connection and at least one multiplier output connection, the multiplier first input connection being coupled to the signal input and the phase shifter first connection and the multiplier second input connection being coupled to the phase shifter second connection. The phase shifter introduces approximately a 90 degree phase shift into the input signal at approximately the frequency of minimum insertion loss.

Abstract: A radar detector including a local oscillator capable of sweeping over a frequency range of sufficient bandwidth to provide a fundamental frequency and, when injected into a multiplier/mixer, harmonics of that fundamental frequency suitable for heterodyning with rf-signals received by an antenna. The heterodyning of the received rf-signals and the local oscillator signal produce an intermediate frequency signal of constant frequency. A sweep controller causes the local oscillator to sweep only through those local oscillator frequencies suitable for heterodyning with those received rf-signals having radio-frequencies which are of interest. The sweep controller causes the sweeping local oscillator not to sweep through those local oscillator frequencies which would heterodyne with received rf-signals that are not of interest.