Leviton Manufacturing Company, Inc.

Leviton Manufacturing Corporation

Clay A Stocklin

David M Rollins

John M Redfield

John H Garthwaite

Denis M Stack

William P Pierson

Wayne R Fukahara

A handheld, battery-powered telecommunications test set which combines the function of tone generator and inductive input probe along with functions such as resistance measurement and continuity/discontinuity. The inductive input is coupled to one input of a differential amplifier, which is susceptible to oscillations caused by leakage currents in the circuits performing other functions. During operation of the inductive input monitor probe, some of these circuits are inactivated, but may still have some leakage current that could flow through them, causing oscillation. Additional circuit elements are added to provide a low resistance pathway to a second input of the differential amplifier to shunt leakage currents from the inactive circuit to the differential amplifier such that the leakage current are converted from a differential signal to a common mode signal and are not amplified. The instrument provides high impedance inputs on circuits which are active when the monitor probe is also active to reduce the leakage currents into the active circuits to an acceptable level.

Portable telecommunications test instrument with inductive probe circuit

Electronic test set for telecommunications, alarm system, and circuit

A handheld, battery-powered telecommunications test instrument with a talk battery circuit capable of supplying power for up to four telephone sets, which may be connected either in series or in parallel. The instrument determines the configuration of the telephone sets as having serial connections or parallel connections by sensing the amount of current flowing through the circuit of the invention. In response to the amount of current, a transistor automatically operates to supply power to the telephone sets as either a voltage source or a current source and maximizes power transfer between the telephone sets. The instrument has a low power mode to reduce current drain on the battery that is automatically engaged when the telephone sets are not in use.

Portable telecommunications test instrument with a talk battery circuit

A handheld battery-powered telecommunications test instrument for monitoring the status of a pair of wires. A tone-generating circuit generates a tone signal in response to the user manually selecting operation in a tone-generating mode. The instrument monitors the pair of wires to determine whether an on-hook, off-hook or ringing signal is present on the wires, and if present, generates an interrupt control signal through a microprocessor. Logic circuitry connected to the microprocessor results in connecting and disconnecting the tone-generating circuit and the pair of wires to selectively apply the tone signal to the wires. In response to the control signal and the user selecting the tone-generating mode, the microprocessor connects the tone-generation circuit to the pair of wires if no control signal is generated, and disconnects the tone-generating circuit if the control signal is generated. The presence of the on-hook, off-hook and ringing signals on the pair of wires is determined by measuring the voltage between the pair of wires. A menu is generated by the microprocessor from which the user can select the frequency and amplitude for the tone signal.

Portable telecommunications test instrument with line condition

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Redmond, WA, United States of America

Clay A Stocklin