Siemens Corporation

Motorola Corporation

Morris L Minch

Theodore W Wagner

Larry V Douglass

Jerome C Leonard

A transformerless hybrid circuit arrangement for a subscriber line interface circuit of a telecommunications exchange is disclosed. A preferred embodiment of the hybrid arrangement comprises a first and a second operational amplifier plus a differential amplifier connected together in the following manner: The non-inverting input of the first operational amplifier is connected to a first reference voltage and the output of this amplifier is connected (1) via a first resistor to one wire of the two-wire subscriber line, and (2) via a third resistor to the inverting input of the amplifier. The non-inverting input of the second operational amplifier is connected to a second reference voltage and to the receiving branch of the four-wire line of the telecommunications exchange. The output of this second operational amplifier is connected via a second resistor to the other wire of the two-wire subscriber line, via a fourth resistor to the inverting input thereof and via a fifth resistor to the inverting input of the first operational amplifier. Each of the two inputs of the differential amplifier are connected, via respective resistors, to one wire of the two-wire subscriber line and to the output of that operational amplifier which is connected to the other wire of the two-wire subscriber line. The output of the differential amplifier is connected to the transmitting branch of the four-wire line of the exchange.

Apparatus for transmitting and/or receiving balanced signals on a

A plug-in module for an electronic device includes a header having conductors therein which extend therefrom to form terminals, and a substrate connected to the header and supporting electronic components connected to the conductors. One component has a projecting part which extends through the header and forms a guide to align the module with a socket, to facilitate plug-in of the terminals of the header. The module may be a channel element to control the frequency of a radio device and may include a resonant element, such as a piezo-electric crystal, and a coil for tuning a resonant circuit. The form for the coil may be the projecting part for aligning the module, and also provide access to a core therein for tuning the circuit when the module is plugged into the chassis. The module may include a conducting housing which cooperates with the header to form an enclosed structure. A grounding pin may be provided to establish a ground connection for the circuit on the substrate and for the housing. The grounding pin can extend from the header a greater distance than the terminals, and cooperate with the coil form in aligning the module when it is being plugged into a chassis.

Plug-in module for electronic device having component forming a guide

A colpitts oscillator having a tank circuit and a common base connected transistor, operating in a linear range, with an emitter-base junction coupled in the tank circuit and a load in the collector circuit thereof for passing current through the load at the frequency of the tank circuit.

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Coral Springs, FL, United States of America

Morris L Minch