Abstract: An inductive amplifier for identifying and tracing wires includes an elongated housing having a probe at one end. A pair of threaded post terminals are provided at the opposite end of the housing for being engaged by the electrical clips of a jumper wire or telecommunications butt set. The threaded post terminals extend from within a recess formed in the inductive amplifier housing for protecting such terminals against damage, for minimizing the likelihood that attached leads will be knocked loose, and for minimizing the chance of the user's body contacting such terminals. The recess in which the threaded post terminals extend is of a size which permits electrical connecting clips of a butt set or jumper wire to extend into the recess and around the terminals. A dividing wall within the recess separates the two terminals from each other. The inductive amplifier includes a tone amplifier for amplifying an audio frequency signal sensed by a probe. The threaded post terminals are a.c.

Abstract: An inductive amplifier for identifying and tracing wires includes a comb filter for nulling out 60 Hz. power line "hum", as well as harmonics of 60 Hz. The inductive amplifier includes a probe for sensing an input signal. The comb filter includes a time delay circuit for providing a delayed output signal that is delayed by 16.67 milliseconds, or one 60 Hz. cycle, compared to the input signal. The comb filter also includes an inverter circuit for providing an inverted output signal that is 180 degrees out of phase with the input signal. The comb filter further includes a summer for summing together the delayed output signal and the inverted output signal to null out harmonic components of 60 Hz. while passing other signals to the output of the comb filter. The nulling method may also use digital processing techniques rather than discrete circuit components.

Abstract: An inductive amplifier for identifying and tracing wires includes an automatic gain control feature for sensing the connection of butt set leads to the inductive amplifier and reducing the gain of the inductive amplifier in such instances to reduce the likelihood of instability or oscillations. The inductive amplifier includes a probe for sensing an input signal which is filtered and amplified for driving either an internal speaker or a speaker in the earpiece of an external butt set. The inductive amplifier includes circuitry for sensing that the leads of the butt set have been connected to the inductive amplifier, and for reducing the gain of the inductive amplifier by a factor of ten under such circumstances.

Abstract: An inductive amplifier for identifying and tracing wires is provided with a pair of threaded post terminals for being engaged by the electrical clips of a jumper wire or telecommunications butt set. The inductive amplifier includes a built-in speaker and a depressible power switch for applying power from a battery to a tone amplifier. A switching transistor couples the battery to the tone amplifier whenever a low impedance path is formed between the pair of threaded post terminals, even if the power switch is not depressed. The built-in speaker is connected in series with the threaded post terminals and is a.c. coupled to the tone amplifier for sounding the tone through either the built-in speaker or through a butt set engaged with the threaded post terminals. The impedance of the built-in speaker is selected to be less than that of the butt set for silencing the built-in speaker when the butt set is connected.

Abstract: An improved instrument for determining the distance to an open fault in a communications line, the instrument taking advantage of the predictable relationship between the current discharge rate in a reference capacitor and resistor and the current discharge rate in a faulty line whose capacitance is a function of the distance to the fault. Provisions are made to keep the meter readings within the usable scale of the meter of the invention by allowing the operator to select from among a range of driving signal frequencies to suit the distance to the fault. Calibration may be made by reference to an internal capacitor or by means of measuring a known length of open circuited line of the type to be tested. Provision is also made to provide for "tuning out" "dirty" short circuits.

Abstract: Circuitry and method for locating buried splices and features of concealed or buried telephone cables or other objects. A small, sealed, low power transmitter is encapsulated with the splice and is concealed or buried therewith. A pair of wires for providing operating power to the transmitter is included in the telephone cable and extends from an exciter circuit to the transmitter. The exciter circuit produces a periodic power waveform on the pair of wires. The transmitter includes a radio frequency oscillator, an amplifier, and a ferrite antenna. The exciter circuit includes an audio frequency oscillator and a driver circuit to provide the periodic power signal to the pair of wires. The radio frequency output signal of the transmitter is modulated by the frequency of the power signal. A portable receiver is tuned to the frequency of the signal transmitted by the buried transmitter. The portable receiver is transported over the general location of the buried splice.

Abstract: A rotational field, such as is produced by the rotation of a motor vehicle alternator rotor, has placed therein a conductor coil which is cut by the lines of force, or flux lines, of the rotating field. The coil is wound upon a magnetic strip which in turn is wrapped around the housing of the alternator. The rotational speed of the alternator rotor will cause corresponding pulses in the coil which are received by a circuit which utilizes the pulse rate to control an output.