Abstract: A digital toner/locator employs tone packets using a 455 Khz carrier. Plural packet quanta provide multiple test modes which are advantageously selected from a probe without requiring returning to the tone generator to change mode.

Abstract: A compact line illuminator for applying an oscillating signal to buried or otherwise inaccessible pipes, cables and conductors so that their location can be traced by detecting an electromagnetic signal emitted by these buried objects. The illuminator includes a circuit for generating a signal suitable for tracing a buried conductor and a holder for a portable power source that can energize the circuit. First and second leads each have a first end connected to the circuit and a second end connected to a corresponding mechanism such as an alligator clip for attaching to a buried conductor. A case encloses the circuit and the portable power source holder and is configured for having the first and second leads wrapped around an exterior of the case. Mechanisms are provided for holding the leads wrapped around the exterior of the case.

Abstract: A handheld device providing an internal view through an obscuring wall or other obscuring surfaces of hidden structural or facilities elements (such as wooden studs, electrical, plumbing, or HVAC), or the absence thereof. A continuous and homogeneous luminescent gas or other visual display material whose optical characteristics change as a result of the applied electric field is used both to simultaneously detect capacitance changes associated with hidden objects and to display those detected those objects. Different types of chambers are disclosed for the gas as well as means to prevent fringing effects. The gas is held just at its ionization level at which point it becomes optically visible. Circuitry is disclosed for controlling the energy source based on current draw or light output of the gas and feedback circuitry is disclosed to neutralize the effects of ambient light. Also disclosed is a device and method for the detection and mapping of electric fields.

Abstract: When a first cable is driven at a locating signal frequency to emit a locating signal, the locating signal can be coupled to a second cable to cause the second cable to generate a false locating signal. As part of discriminating the false signal from the locating signal, the locating signal is generated at the locating signal frequency and phase shifted to produce a phase shifted locating signal frequency. A reference signal is impressed with the phase shifted locating signal frequency. A coupling configuration couples the locating signal frequency onto the first cable to generate the locating signal subject to a coupling configuration phase shift. The phase shifted locating signal, as part of the reference signal, can compensate for the coupling configuration phase shift in the locating signal as emitted by the first cable.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: A locating device, in particular a hand-held locating device, for detecting objects enclosed in a medium, including an output unit for displaying at least one output variable correlated with a measuring signal of at least one sensor of the locating device, the output unit having a first dynamic range for displaying the output variable correlated with the measuring signal. At least one further dynamic range having a changed sensitivity compared to the first dynamic range is displayable via the display unit.

Abstract: A magnetic field position sensing device for sensing the position, on a front surface of a wall, of a magnet of known magnetic field intensity secured to a rear surface of the wall. The sensing device has a magnetic field transducer which produces signals proportional to the strength of the magnetic field detected. These signals are treated in a microcontroller and compared to a reference signal value representative of the magnetic field intensity of the magnet, when not obstructed, whereby to generate signals to a display device which displays a numerical value indicative of the thickness of the wall. Audible/visual signaling devices are also provided whereby to direct the movement of the sensing device by a user person to locate same on the front surface of the wall substantially adjacent the magnet and this is accomplished by displacing the sensing device in a diminishing spiral path.

Abstract: A compact line illuminator for applying an oscillating signal to buried or otherwise inaccessible pipes, cables and conductors so that their location can be traced by detecting an electromagnetic signal emitted by these buried objects. The illuminator includes a circuit for generating a signal suitable for tracing a buried conductor and a holder for a portable power source that can energize the circuit. First and second leads each have a first end connected to the circuit and a second end connected to a corresponding mechanism such as an alligator clip for attaching to a buried conductor. A case encloses the circuit and the portable power source holder and is configured for having the first and second leads wrapped around an exterior of the case. Mechanisms are provided for holding the leads wrapped around the exterior of the case.

Abstract: A testing system includes a hand-held transmitter that plugs into a receptacle electrically coupled to a selected branch circuit. The transmitter includes a circuit effective to test an arc fault circuit interrupter electrically coupled to the branch circuit by creating a first pulse on the branch circuit that is effective to trip the arc fault circuit interrupter. The transmitter can perform at least one additional test including: determining whether the receptacle is wired properly; determining a location of a circuit interrupting device electrically coupled to the branch circuit by creating a second pulse on the branch circuit that can be sensed by a receiver located proximately to the respective circuit interrupting device and broadly tuned about a frequency of the second pulse; and testing a ground fault circuit interrupter electrically coupled to the branch circuit by creating a third pulse on the branch circuit that is effective to trip the ground fault circuit interrupter.

Abstract: A portable locator for detecting a buried object characterized by an electromagnetic (EM) field emission employing three-dimensional (3D) sensor arrays each having three substantially-identical EM field sensors disposed on a flexible annular wall having a radial centroid defining a sensing axis. The flexible annular sensors are retained in substantial concentricity with the corresponding sensing axes disposed in substantial mutual orthogonality. A pair of 3D sensor arrays disposed on a first axis substantially orthogonal to a second axis defined by another pair of EM field sensors each having a sensing axis disposed along the second axis. The locator introduces a user-reconfigurable user interface (UI) employing a “sticky” ratcheting audio UI and a hollow hinge assembly for redisposing the sensor assembly from an operating to a storage disposition.

Abstract: A sensing device having a sensing surface for placing against a wall for detecting objects behind a wall lining has first and second sensors, each sensor including at least first and second capacitor plates and associated resistors forming RC circuits having time constants dependent on the adjacent wall material. Detection circuits connected to the RC circuits provide first and second voltage signals having amplitudes dependent on capacitance changes. A processor effects a comparison of the first and second voltage signals, and compares them to establish the magnitude of the voltage difference between the voltage signals, indicating a detected object center position when the difference signal is less than a predetermined value.

Abstract: A service tee marker fixture comprises a disk marker and a cylindrical attachment sleeve fastened concentrically to the disk marker and constructed of a flexible material which provides a releasable friction fit with a service tee cap. For certain sleeve materials a stiffener plate is used to secure an end portion of sleeve adjacent to the disk marker. Detents are formed inside the attachment sleeve to grip matching ribs on the cap. An integrally formed inwardly-extending annular flange at an open end of the sleeve helps retain the sleeve on the cap. When installed the wire coil is horizontal and the marker shields the tee, and is further centered over a centerline of the main pipe. A novel method is also disclosed for using the service tee marker fixtures to survey and locate service line end points.

Abstract: A magnetic indexer for locating a device producing a magnetic field in a blind or inaccessible position of a work piece. A magnet is initially placed on a first side of the work piece such that a magnetic field produced by the magnet extends through the work piece and substantially perpendicular to a surface of the work piece. A device comprising a plurality of probes for sensing magnetic fields is then positioned over a second surface of the work piece. The probes are then moved over the second surface to determine the location of the axis of the magnet via the strength of the sensed magnetic field. Once the position of the axis of the magnet is determined, the work surface is either marked or worked on through the platform on which the probes are positioned. In particular, a hole may be accurately drilled or otherwise formed directly over the magnet even when the first surface of the work piece cannot be seen.

Abstract: A human-portable utility locator system for locating and tracing a buried utility line characterized by an electromagnetic field emission. The locator may include a horizontal spaced sensor pair for detecting the horizontal field asymmetry of the emitted field in one or more independent frequency bands, which is employed to assist in determining an accurate “virtual depth” measurement for producing detection events. An event detector may be disposed to detect events corresponding to extremum in the B-field gradient with respect to time and a user interface (UI) coupled to the event detector signals the detected event to a user. In a preferred embodiment, one pair of spaced-apart 3D magnetic sensor arrays is disposed substantially orthogonal to another intermediate spaced-apart pair of sensors.

Abstract: A multiple sensitivity stud sensing device for determining a location of objects behind a wall lining has a housing with a surface for moving over the wall lining. Within the housing are a capacitive sensor with first and second capacitances located adjacent the surface and control circuitry. The control circuitry includes a detecting circuit connected to the sensor for providing a detection signal related to an imbalance between the first and second capacitances, and a processor for receiving the detection signals and providing a display signal. A display is located on the housing for indicating location of an object behind the wall lining. The processor compares a detection signal to stored predetermined threshold values of detection signals associated with different wall lining thicknesses and displays a thickness value to the user.

Abstract: A system for testing concealed ducts including a pull cable and a transmitter, the transmitter including a transmission means for emitting radiation disposed at one end of the pull cable and at least one electric wire disposed inside the pull cable, wherein the electric wire or wires enables electrical connection between the transmitter and the transmission means, and a receiver for receiving signals from the transmission means and for indicating strength of the received signals. The scope of the invention includes methods of finding blockage within a conduit pipe and finding the path of a conduit pipe, built into a partition, by inserting a pull cable into a conduit pipe and detecting the location of the front end of the pull cable.

Abstract: An electronic metal detector having transmit electronics includes switching electronics arranged and adapted to generate a transmit signal. The transmit electronics includes at least two power sources, and is connected to a transmit coil arranged and adapted to transmit an alternating magnetic field. The switching electronics are adapted and arranged to switch a first voltage of one power source to the transmit coil for at least a first period and also a third period, and to switch a second voltage of the other power source to the transmit coil for at least a second period. Receive electronics are arranged to receive and process a receive magnetic field during at least some of the second period and fourth period to produce an indicator output, at least indicating the presence and a characteristic of some metal targets under the influence of the magnetic field.

Abstract: A testing system includes a hand-held transmitter that plugs into a receptacle electrically coupled to a selected branch circuit. The transmitter includes a circuit effective to test an arc fault circuit interrupter electrically coupled to the branch circuit by creating a first pulse on the branch circuit that is effective to trip the arc fault circuit interrupter. The transmitter can perform an additional test of determining whether the receptacle is wired properly.

Abstract: A line locator includes a signal detector to detect signals from an underground line; an error modeler that models a phase error in the signal from neighboring underground lines; and an enhanced electromagnetic field modeler that provides a location of the underground line based on the signal and a result from the error modeler.

Abstract: A system for selectively grounding each of a plurality of short-haul buried utility conveyances coupled to a common long-haul buried utility conveyance to enable a conveyance locating signal transmitted through the long-haul conveyance to travel from the long-haul utility conveyance to a selected short-haul utility conveyance. The system includes a first optical switch for selecting each of the plurality of short-haul utility conveyances to be grounded, where the first optical switch is adapted to receive an optical signal and selectively output the optical signal on one of a plurality of optical fibers; and a second optical switch coupled to each of the plurality of optical fibers for grounding each short-haul utility conveyance in response to the optical signal on a corresponding optical fiber.

Abstract: The present invention relates to a method for graphically displaying a sectional image of an object under examination (1, 18) having objects (2, 17) situated therein, in particular for the display of a sectional image of a building wall. The invention provides that the sectional image with the objects (2, 17) situated in the object under examination (1, 18) is displayed already while data acquisition by the position detector (3, 19) is taking place.

Abstract: A stray voltage detector has a portable housing carrying a pair of electrostatic charge sensors spaced apart along an axis, and a pair of field intensity indicators, each indicator connected to an associated one of the charge sensors and constructed to indicate a relative electric field intensity at its associated sensor. The voltage detector is constructed to provide simultaneous electric field intensity feedback from both indicators to an operator moving the housing along the axis over a surface with a localized region at an elevated voltage, to assist in locating the localized elevated voltage region. The detector is useful for locating high-voltage regions, even when there is little or no current flowing through such regions to generate a magnetic field.

Abstract: A metal detector for detecting the presence of a ferrite object in the proximity of inductively coupled sensor having overlapping D shaped transmitter and receiver coils. The metal detector has a phase shift circuit to phase shifting a sensor output signal by a known amount and a switch operating in synchronisation with an excitation signal of the sensor for sampling the amplitude of the phase shifted output signal.

Abstract: Portable locators are disclosed for finding and mapping buried objects such as utilities. A articulatable antenna node configuration and the use of Doppler radar and GPS navigation are also disclosed.

Abstract: A sensing device having a sensing surface for placing against a wall for detecting objects behind a wall lining has first and second sensors, each sensor including at least first and second capacitor plates and associated resistors forming RC circuits having time constants dependent on the adjacent wall material. Detection circuits connected to the RC circuits provide first and second voltage signals having amplitudes dependent on capacitance changes. A processor effects a comparison of the first and second voltage signals, and compares them to establish the magnitude of the voltage difference between the voltage signals, indicating a detected object center position when the difference signal is less than a predetermined value.

Abstract: The present invention is a technique for locating and identifying a failed filter/arrester in an underground conveyance such as a fiber optic cable. A sensor is installed in the filter/arrester housing to sense grounding of a cable locating frequency. The sensor will monitor the cable locating signal that is normally on the cable and blocked by the filter arrester to ground. A small radio frequency oscillator (85 to 88 Hz), also installed inside the filter housing, is activated by the sensor. The RF signal is detected above ground with standard cable locating equipment. A warning indicator such as an indicator light may also be installed on the outside of the filter housing. The indicator is also activated by the sensor. In that way, the particular failed filter can be identified if multiple filters are installed at that location. The power that will be required to operate the RF transmitter and indicator will be obtained from the voltage passing through the cable.

Abstract: The present invention is directed to an electrical wiring inspection system that includes a user interface device including processor circuitry, a user interface, and a first communications interface. The first communications interface is configured to transmit configuration data related to a plurality of electrical test procedures and receive test data corresponding to a plurality of electrical parameters. A branch circuit analysis device is configured to be coupled to the user interface device via the first communications interface and at least one branch circuit by at least one test connector. The branch circuit analysis device includes processor circuitry, branch circuit test circuitry configured to perform one or more of the plurality of electrical test procedures, and a second communications interface configured to transmit and receive configuration data related to a plurality of electrical test procedures and transmit and receive test data corresponding to a plurality of electrical parameters.

Abstract: A fiber optic cable can comprise a tape that extends along the cable and that facilitates locating the cable when the cable is buried underground. The tape can comprise a film of nonconductive material, such as plastic, with an overlaying pattern of conductive patches. The conductive patches can comprise regions of metallic film laminated with or otherwise adhering to the nonconductive film. Spacing between the conductive patches can provide patch-to-patch isolation so that the ends of the cable are electrically isolated from one another. Field personnel can locate the underground cable by scanning the ground with a metal detector.

Abstract: The invention relates to a locating device, in particular a handheld locating device (10), for detecting objects which are enclosed in a medium, said device having a housing (12) and at least one sensor apparatus, which is arranged in the housing (12), as well as an opening (24) which penetrates the device (10). The invention proposes that the opening (24) can be illuminated in a pulsating manner using at least one light source (34) which is arranged in the measuring device, the illumination repetition rate being dependent on the type of object detected.

Abstract: A magnetic indexer for locating a device producing a magnetic field in a blind or inaccessible position of a work piece. A magnet is initially placed on a first side of the work piece such that a magnetic field produced by the magnet extends through the work piece and substantially perpendicular to a surface of the work piece. A device comprising a plurality of probes for sensing magnetic fields is then positioned over a second surface of the work piece. The probes are then moved over the second surface to determine the location of the axis of the magnet via the strength of the sensed magnetic field. Once the position of the axis of the magnet is determined, the work surface is either marked or worked on through the platform on which the probes are positioned. In particular, a hole may be accurately drilled or otherwise formed directly over the magnet even when the first surface of the work piece cannot be seen.

Abstract: A detector for detecting a buried current carrying conductor includes a digital signal processor, magnetic sensors, and a power supply unit. The power supply unit is a switched mode power supply which incorporates a proportional integral differential controller feedback algorithm and which is managed by the digital signal processor. The load and source voltage are monitored by the digital signal processor and a look-up table is used to control a pulse width modulator, which drives a single ended primary induction controller. The digital signal processor processes and compares signals received from the sensors to calculate a depth of a buried conductor. The self-generated noise of the power supply unit does not interfere with the frequency bands of detection of the detector.

Abstract: Discriminating between a cable locating signal and a false cable locating signal is described. A reference signal, which contains a locating signal frequency impressed on it, is transmitted in a way which provides for detection of a phase shift between the locating signal and the false locating signal. Based on the phase shift, a receiver is used to distinguish the locating signal from the false locating signal.

Abstract: An arrangement and an associated method are described in which a boring tool is moved through the ground within a given region along a path in which region a cable is buried. The boring tool and the cable transmit a boring tool locating signal and a cable locating signal, respectively. Intensities of the boring tool locating signal and the cable locating signal are measured along with a pitch orientation of the boring tool. Using the measured intensities and established pitch orientation, a positional relationship is determined to relative scale including at least the boring tool and the cable in the region. The positional relationship is displayed to scale in one view. The positional relationship may be determined and displayed including the forward locate point in scaled relation to the boring tool and the cable. Cable depth determination techniques are described including a two-point ground depth determination method.

Abstract: A blind spot targeting system for establishing a cutting point includes a locator with a housing having an indicator and a signal-sensing device. The housing has a hole therethrough, and the indicator is in electronic communication with the signal-sensing device for indicating a cutting point on a first side of a structure. A transmitter is also included, which has a complementary hole therethrough. The transmitter is for placement on a second side of the structure for emitting a signal, which the signal-sensing device senses. The indicator in communication with the signal-sensing device indicates alignment of the hole and the complementary hole to establish the cutting point for cutting through the hole into the first side of a structure and possibly through the second side of the structure in a direction of the complementary hole.

Abstract: A surface tracker includes a tubular marker body having an interior electronic marker and a visual indicator attached to an upper end of the marker body which extends away from the marker body. When deployed, the marker body is mostly underground and the visual indictor extends upwardly from the ground level to provide above-ground visual recognition. The electronic marker may be a passive electronic marker that includes a ferrite core assembly having a longitudinal axis which is generally parallel to a longitudinal axis of the marker body. The visual indicator may be a plurality of resilient filaments which pass through a hole in a tab portion of the marker body at the upper end thereof, the filaments being folded about the tab portion and secured to the tab portion using a heat-shrink tube. In an exemplary embodiment, the filaments extend about six inches from the marker body and are brightly colored. Multiple trackers can be used to mark the path of a buried utility.

Abstract: The object of the present invention is a device for the detection of concealed objects which exploits a transceiving system of the microwave type.

Abstract: An apparatus and method to locate and mark the surface position of an underground utility while maneuvering along the path of the utility. The apparatus uses an underground utility detector that responds to the location of an underground utility to continually position a carriage proximate vertical of the utility. Marker systems are aligned with the carriage and apply either a unique paint symbol on pavement or a spike in the ground. The apparatus is configured to use an underground utility detector or positioning equipment that generate positional signals. The apparatus may be configured to mark utility positions at predetermined intervals and mark utility offset positions. The apparatus may be attached to a vehicle, towed by a vehicle, motorized or propelled by a person.

Abstract: A system for locating a junction box installed within the framework of a structure and behind a wall includes a first magnet mounted on a plate with the plate being removably mounted to a junction box, a spring actively biasing the magnet outwardly from the plate, and a second magnet located outside of the wall used to identify the location of the first magnet, and thereby, the electrical box, behind the wall.

Abstract: In a method for locating objects enclosed in a medium, a detection signal is generated by at least one capacitive sensor. The detection signal penetrates the medium that is to be analyzed in such a way that information is obtained about the objects that are enclosed in the medium by evaluating the detection signal, particularly by measuring impedance. In order to evaluate the detection signal, an algorithm is used that separates the measured signal into signal parts originating from the enclosing medium and signal parts originating from the object enclosed in the medium. A measuring device carries out the inventive method.

Abstract: An electronic marker locator with a digital architecture for providing accurate and consistent estimation of the signal strength is presented. The marker locator includes a Digital Phase-Locked Loop (DPLL) structure. The electronic marker locator transmits known and adjustable frequency bursts corresponding to the markers to be located while synchronously capturing the signals returned from the markers. Because of the convergence properties of the DPLL, very consistent measurements of the reflected marker signal field strength are possible, resulting in both an improvement of maximum detection depth and depth accuracy. Further, the analog front-end hardware can be reduced, offering wider resistance to component tolerances, lower calibration and test times, and flexible frequency selectivity.

Abstract: A new approach for locating an underground line described herein remains accurate in the face of bleedover by including both amplitude and phase from at least two magnetic field strength sensors in the measurement set. A numerical optimization step is introduced to deduce the positions and currents of each of several cables, of which one is the targeted cable and the others are termed bleedover cables. Furthermore, some embodiments of the method accounts for practical problems that exist in the field that relate to reliable estimation of cable positions, like the phase transfer function between transmitter and receiver, the estimation of confidence bounds for each estimate, and the rejection of false positive locates due to the presence of noise and interference.

Abstract: A method for detecting a network cable connection state is disclosed. The method includes detecting a change of connection state of a connector using a sensor that resides in the connector and generating cable connection state information from the information supplied by the sensor. Cable connection state information is communicated to a connection state monitoring utility for facilitating network fault detection. The cable plug or socket may also contain an embedded processor, memory and unique identification.

Abstract: A detector 1 for detecting a current carrying conductor determines the presence of a current carrying conductor one or more of passive or active modes. In the passive modes, the detector 1 detects either very low frequency radio signals re-radiated from a conductor or electromagnetic radiation produced by a conductor as a result of mains voltage carried in the conductor, or in a nearby conductor. In the active mode, an alternating signal from a dedicated signal generator is coupled into the buried conductor. Signals are induced in a pair of antennae 3, 5 in the detector 1, and the signals are processed in each of these modes simultaneously. The outputs of each of the modes are convolved to produce an audio and/or visual alert if a current carrying conductor is detected by any of these modes.

Abstract: A detector 1 for detecting a current carrying conductor has a pair of vertically spaced antennae 3, 5 to detect the magnetic radiation produced by a current carrying conductor as a result of one or both of the mains power supply or an electromagnetic signal which is induced in the conductor by a dedicated signal transmitter. The detector 1 continuously calculates the depth of a buried conductor and if the buried conductor is above a predetermined minimum depth then the detector 1 triggers an audio and/or visual alarm. By reducing the sensitivity of the antennae 3, 5, the lateral offset range for which the alarm sounds is reduced and the location of a buried conductor can be determined.

Abstract: Portable locators are disclosed for finding and mapping buried objects such as utilities. A articulatable antenna node configuration and the use of Doppler radar and GPS navigation are also disclosed.

Abstract: A multi-scanner device having a detection unit and an outlet tester that can be selectively connected together for convenient use and easy storage. Preferably, a plug on the outlet tester is inserted into a non-functional socket located on the detection unit to form a multi-scanner device with a detachable outlet tester.

Abstract: A human-portable utility locator system for locating and tracing a buried utility line characterized by an electromagnetic field emission. The locator may include a horizontal spaced sensor pair for detecting the horizontal field asymmetry of the emitted field in one or more independent frequency bands, which is employed to assist in determining an accurate “virtual depth” measurement for producing detection events. An event detector may be disposed to detect events corresponding to extremum in the B-field gradient with respect to time and a user interface (UI) coupled to the event detector signals the detected event to a user. In a preferred embodiment, one pair of spaced-apart 3D magnetic sensor arrays is disposed substantially orthogonal to another intermediate spaced-apart pair of sensors.

Abstract: A method for tracking a position of an object includes using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, wherein a measurement of at least one of the field strengths is subject to a distortion. Rotation-invariant location coordinates of the object are calculated responsively to the measured field strengths. Corrected location coordinates of the object are determined by applying to the rotation-invariant location coordinates a coordinate correcting function so as to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths.

Abstract: An electrified wall panel in a modular furniture environment includes a plurality of multi-port electrical distribution blocks diversely located throughout the panel. Certain ones of the multi-port electrical distribution blocks are fixed to wall panel frame members and other ones of the multi-port electrical distribution blocks are free of the wall panel. A plurality of jumper cables, each having connectors at opposite cable ends are adapted to mate with any one of the multi-port electrical distribution block ports. The cables electrically interconnect the distribution blocks to form one complete circuit. There are a plurality of electrical receptacles, each having an electrical connector near one end which are electrically coupled to a port of a corresponding multi-port electrical distribution block. The system is assembled by fixing a jumper mounting bracket to a jumper cable near one end of the jumper cable. The jumper mounting bracket is attached to a support member.

Abstract: A detector 1 for detecting a buried current carrying conductor comprises a digital signal processor 16 and a power supply unit 25. The power supply unit 25 is a switched mode power supply which incorporates a proportional integral differential controller feedback algorithm 33 and which is managed by the digital signal processor 16. The load 31 and source 26 voltage are monitored by the digital signal processor 16 and a look-up table. 35 is used to control a pulse width modulator 27, which drives a single ended primary induction controller 29. The self-generated noise of the power supply unit 25 does not interfere with the frequency bands of detection of the detector 1.