Abstract: A circuit for increasing the inductance of a transformer as used in a telephone line circuit. An operational amplifier with appropriate feedback is connected across a separate winding of the transformer to provide the reactive inductance. To compensate for changes in resistance of the winding, a field effect transistor is controlled by the same amplifier output to provide a positive resistance in the feedback path and thus maintain balance.

Abstract: A printed wiring card tab protector for shielding the gold plated printed wiring card tabs from contamination with solder during a wave soldering process. The protector has a first fold that slips over the tabs and is thereby frictionally held in place while a second fold deflects away the solder wave.

Abstract: A device for selectively connecting a plurality of circuit elements in a thick/thin film circuit comprising, a pivot pin mounted to the film circuit and a manually rotatable contact element mounted to the pin. Contact fingers emanating from the contact element communicate with contact pads connecting a different set of film circuit elements together each time the contact element is rotated.

Abstract: In a hold circuit including a relay normally latched and connecting the hold circuit to a subscriber telephone line, a first hold release circuit outputs a trigger signal to a silicon controlled rectifier turning on the rectifier responsive to a sensed drop in line potential, thereby providing an electrical path for the discharge of a capacitor. The capacitor discharges through the coil of the relay unlatching the relay and releasing the hold circuit from the line. The hold circuit is also arranged to be released by a second hold release circuit which outputs a trigger signal to the silicon controlled rectifier responsive to a pre-arranged timing interval.

Abstract: An arrangement for testing a plurality of subscriber lines, which are operationally connected to an electromechanical switching system is shown. Operational service is to be transferred from the electromechanical switching system to a digital switching system. This arrangement provides for automatically verifying the connection of the subscriber lines to the digital switching system and determining whether the proper ring signalling is transmitted to each subscriber.

Abstract: An arrangement for automatically testing a plurality of subscriber lines, which are operationally connected to an electromechanical switching system is shown. Operational service is to be transferred from the electromechanical switching system to a digital switching system. This arrangement provides for automatically verifying whether the digital switching system is applying the proper ringing signal to each subscriber by a comparison with that applied by the electromechanical switching system.

Abstract: A telephone feature assigment circuit for use in a telephone having a plurality of features and pushbuttons. Each feature can be assigned to a selected one of the pushbuttons. The telephone also includes a microprocessor and visual and audible prompting devices. These devices are operated by the microprocessor in response to prolonged operation of a selected pushbutton. Keypad initiated signals are then provided to identify the feature to be assigned to the selected pushbutton. The microprocessor subsequently causes the assigned feature to be performed in response to momentary operation of the selected pushbutton.

Abstract: A circuit which locks the signaling circuit of a telephone station. A microprocessor disconnects a keypad from an associated tone generator upon detection of operation of a lock button. The microprocessor connects the keypad to the tone generator upon detection of operation of the lock button and a predetermined unlock code provided by the keypad.

Abstract: An arrangement for testing a single subscriber line, which is operationally connected to an electromechanical switching system is shown. Operational service is to be transferred from the electromechanical switching system to a digital switching system. The arrangement provides for isolating subscribers which share common line equipment, for verifying the subscriber's line and its ringing characteristics.

Abstract: A telephone substation transmitter muting circuit used in a substation having a hold function wherein, a transistor turns on connecting a muting network across the handset transmitter whenever the hold circuit is activated.

Abstract: A device for selectively connecting a plurality of circuit elements in a thick/thin film circuit comprising, a pivot pin mounted to the film circuit and a manually rotatable contact element mounted to the pin. Contact fingers emanating from the contact element communicate with contact pads connecting a different set of film circuit elements together each time the contact element is rotated.

Abstract: In a hold circuit including a silicon controlled rectifier (SCR) normally turned on and connecting the hold circuit to a subscriber line, a first hold release circuit outputs a trigger signal to a transistor turning off the transistor and disconnecting a line seizing network. A second hold release circuit outputs a trigger signal to a second transistor responsive to the line seizing network being disconnected. The second transistor connects a load resistor across the SCR dropping the holding current flowing through the SCR causing it to turn off. The second hold release circuit is also arranged to output its trigger signal to the second transistor responsive to a pre-arranged timing interval.

Abstract: In a telephone substation employing a dual tone multi-frequency signal generator, the common switch functions of disabling the transmitter and muting the receiver are performed by transistor devices responsive to a control signal produced by the signal generator. A bias voltage provided by the transistor device associated with the transmitter prevents dialing signals from reverse biasing the transistor device associated with the receiver and defeating receiver muting.

Abstract: In a hold circuit connectable to a subscriber telephone line, a silicon controlled rectifier is turned on by a user operated momentary pushbutton connecting the positive side of the line to the hold circuit. A comparator circuit sensing the initial value of the loop voltage, turns on a transistor and connects a line seizing network across the subscriber line.

Abstract: In a hold circuit connectable to a subscriber telephone line, a line voltage storage capacitor is momentarily connected to the subscriber line charging to line potential and providing trigger current to a silicon controlled rectifier. When sufficient trigger current is gained the silicon controlled rectifier turns on discharging the capacitor through a latching relay coil and a transistor, thereby turning on the relay and connecting the hold circuit. The transistor is turned on by a bias voltage from the capacitor when the silicon controlled rectifier is turned on.

Abstract: An arrangement for providing a subscriber line with an operating potential. The energy to the line is transferred thereto inductively at a fixed frequency and includes the rectification means on the subscriber side of the inductor. The amount of energy transferred to the line is controlled by pulse width. The control pulse width circuit includes means to decrease the energy transfer above a level at which a subscriber station internal regulation would be defeated.