Abstract: There is provided a voltage detecting circuit in which a consumed electric current is small, accuracy is high, and an erroneous operation seldom occurs. In the voltage detecting circuit constituted by a bias circuit, a current mirror circuit, a load MIS transistor connected to the current mirror circuit in which current drive capability is changed by an output voltage of the bias circuit, and an amplifying inverter circuit, a potential change at an output node of the current mirror circuit at the time of detection and release of a power supply voltage is steeply changed, so that a leak current of the whole circuit can be decreased and a consumed electric current can be reduced.

Abstract: A system and method is provided for detecting an island condition using active detection. The active detection involves biasing the voltage, frequency, current or phase of a distributed resource connected to a utility network. Biasing the distributed resource involves inducing a change of voltage, frequency, current or phases above or below the normal operating values. The impact of this biasing on the system operating parameters can then be measure to determine if an island condition exists. Once an island condition has been detected, the system can initiate an anti-islanding procedure to remove the distributed resource from the utility network such as opening a breaker connecting the distributed resource to the network. Additionally, the system and method can include a passive element for detecting frequency and voltage (or other parameters) shifts above certain points.

Abstract: A system for locating a circuit interrupter associated with a selected branch circuit. The system includes a passive transmitter that creates a current spike at a predetermined frequency and a receiver broadly tuned about that predetermined frequency. The current spike signal has a sufficiently short spike duration and a sufficient amplitude so as to substantially minimize development of a sympathetic signal on other branch circuits adjacent to the selected branch circuit. The passive transmitter includes a voltage controlled switch in series with a charge storage device. The receiver drives a user-perceivable signaling device upon sensing the current spike. Related subsystems and methods are also disclosed.

Abstract: A switchless, hand-held probe and method for detecting and alerting a user to the presence of an AC voltage on a conductor that minimizes the intermittent activation of the probe's indicator due to static charge build-up. The probe comprises an antenna, an indicator, detector circuitry and activation circuitry. The probe alerts a user through the use of an indicator to the presence of electrical energy on a conductor. The antenna senses the electrical energy radiated from the conductor. When the electrical energy sensed by the antenna satisfies a particular measurement threshold, a signal is generated by the detector circuitry and received by the activation circuitry. The activation circuitry activates the indicator after a sufficient number of signals are received from the detector circuitry during a given period of time.

Abstract: A circuit configuration has an integrated semiconductor element, preferably, an intelligent power semiconductor, and a display element. A display element diagnoses and displays disturbances in the integrated semiconductor element. The display element connects electrically firstly to the diagnostic output of the semiconductor element and secondly to the load output of the power stage, and contains light-emitting semiconductor diodes. The light-emitting diodes are connected in antiparallel and output to their environment visual information items and can be distinguished in accordance with the current fed to them.

Abstract: A method of controlling a relative movement of a cutting blade and a workpiece which are moved relative to each other by a movement device in an operation with a machine tool. The method includes a step of bringing the cutting blade and an object into contact with each other, by moving at least one of the cutting blade and the object toward each other by the movement device, and a step of controlling the relative movement on the basis of a relative position of the cutting blade and the object which is detected by the movement device upon the contact of the cutting blade and the object with each other.

Abstract: The present invention is a non-invasive cable tester. The cable tester comprises a sensor for detecting an electric field emitted by a live electric cable. The resulting signal from the sensor is then filtered, amplified, and compared to a threshold value to determine the energization status of the electric cable. A meter can be provided to get a reading of the amplified signal that can be compared to a predetermined threshold value. Also, a detector circuit can be provided that includes a comparator in electrical communication with a light-emitting device such as a light-emitting diode. The detector circuit processes the amplified signal and compares it to a predetermined threshold value. If the electric cable is energized, the output of the comparator either causes the light-emitting device to emit light or not emit light, as desired. This enables an operator to determine the status of the electric cable simply by determining whether the light-emitting device is lit.

Abstract: A fault indicator for indicating the occurrence of a fault in an electrical conductor has a housing, a high capacity battery, at least one light emitting diode (LED) visible from the exterior of the fault indicator upon the occurrence of a fault, and electronic circuitry for sensing a fault, for actuating the LEDs to indicate a fault and to provide a timed reset of the LEDs to a non-fault indicating condition a predetermined time after the fault has occurred. The electronic circuitry, including a microprocessor that is normally in a sleep mode, conserves energy by drawing insubstantial current from a high capacity battery during non-fault conditions. During fault conditions, a light sensor senses the ambient lighting conditions and the microprocessor reduces current supplied to the LEDs under reduced lighting levels, such as night, further conserving battery life. The LEDs may also be operated at an intermediate illumination level, such as at dusk or dawn.

Abstract: An electrical circuit tester for allowing a user to efficiently test electrical fixtures and switches. The electrical circuit tester includes a housing that has a plurality of prongs that extend from the housing. The prongs are adapted for engaging an electrical outlet of a building. A plurality of lights is coupled to the housing. The lights are lit in a pattern indicating a state of the electrical outlet. A speaker is coupled to the housing. The speaker is for creating an audible tone when the prongs engage the electrical outlet.

Abstract: An integrated circuit on a system board is used, for example, in a digital audio device (such as a DVD or A/V receiver). The integrated circuit includes a digital-to-analog converter and the system board may include circuitry to mute the analog output of the device under certain predefined conditions. Because it may not be known in advance by the designer of the integrated circuit whether the circuit is activated by a signal in a high state (polarity) or a low state, the integrated circuit includes a detector which detects and stores the required polarity. When it is necessary for the circuit to be activated, the detector provides a signal of the correct polarity.

Abstract: An audible test circuit has a body having a plurality of prongs extending therefrom and having a plurality of lights thereon. A four way bridge rectifier circuit has a voltage steering circuit for producing a DC output voltage of known polarity located in the body. An audible alarm, is coupled to the four way bridge rectifier circuit for producing an audible alarm when power is applied to the rectifier circuit while lamps indicate the plurality of circuit connections. The audible test circuit may include a lamp socket-to-alligator clip attachment for coupling the alligator clip to the circuit. There is also a lamp socket-to-alligator clip attachment.

Abstract: A circuit tester (1) for testing circuit integrity in a series-wired string of Christmas fairy lights powered by domestic mains electricity.

Abstract: A circuit test light includes a reel-shaped housing formed of a light-transmitting material, with a light source disposed in the hub of the reel and connected to the proximal ends of two elongated test leads, the distal ends of which are respectively connected to connector assemblies. At least one of the connector assemblies includes a base connector and a plurality of adapter connectors selectively connectable to the base connector for use with different types of test terminals. The leads can be wound around the hub of the reel for storage when not in use, being retained in place by a suitable strap.

Abstract: A voltage sensing apparatus includes an output for a voltage tap point that is useful in representing the voltage on a conductor that passes through the voltage sensing apparatus. The voltage sensing apparatus also performs the function of a separable insulated conductor, e.g. a conventional bushing or bushing insert as utilized in the electrical power distribution field. The voltage sensing apparatus includes a molded body having an embedded capacitance screen that provides the output. The body is molded about the capacitance screen. An arrangement is provided for locating the capacitance screen within the molded body. In a preferred embodiment, the capacitance screen is molded from a conductive plastic preferably formed with an open mesh or screen structure that permits the free flow of molding material.

Abstract: An electrical test probe tip capable of establishing an electrical connection to test objects on a circuit board and particularly to rounded or irregularly shaped test objects. A preferred embodiment of the notched electrical test probe tip of the present invention has a probing tip with a longitudinal planar axis. Two planar contact surfaces substantially form an inverted “V” from the longitudinal planar axis when viewed from either side of the probing tip. The probing tip has a notch defined therein when viewed from both the front and the back. Optionally the preferred embodiment may have an exterior insulating coating. This configuration can be constructed by starting with an elongate electrically conductive blank and drilling an at least partial central bore substantially parallel to the longitudinal planar axis. Then two planar cuts are made removing a portion of the blank to expose the contact surfaces.

Abstract: A circuit tester (1) for testing circuit integrity in a series-wired string of Christmas fairy lights powered by domestic mains electricity, the tester comprising or including a housing; a probe including a pair of matching current sensors (1,2) protruding from the housing, the probe being adapted to be positioned between a respective pair of wires extending from a fairy light bulb socket, each sensor in the probe being electrically connected to a respective one of a matching pair of signal amplifiers (3,4) to provide a pair of amplified signals, one for each sensor; a logic gate (5) for receiving amplified signals output from the pair of signal amplifiers and comparing said signals for matching characteristics, the gate providing an output signal to a first display (6) on or in the housing indicative of received and matching signals and a, different, output signal to a second display (7) on or in the housing indicative of received mismatching signals from the amplifiers, the latter thereby indicating a disco

Abstract: A power detector (50) detects a power level of an amplified signal (S20) produced by a power amplifier (16) on the same integrated circuit (100). The power detector compensates for an effect of temperature variations on the magnitude of the detected power level.

Abstract: A circuit tester (1) and method of testing the integrity of a series-wired electrical circuit are disclosed, such as a string of Christmas fairy lights powered by domestic means electricity, through the use of a tester comprising a pair of matching AC current sensors (1, 2) adapted to be positioned adjacent to a pair of wires forming part of the circuit to be tested, such as between or around a pair of wires (29, 30) extending from a fairy light bulb socket (31), the tester then feeding the signals to a matching pair of signal amplifiers (3, 4) and thereafter to a logic gate (5) which provides an output signal to a first display (6) indicating the receipt of matching signals and hence a closed circuit between the wires, and in the event of receipt of mismatching signals from the amplifiers a different output signal is sent to a second display (7) which indicates a discontinuity in the circuit between the pair of wires being tested, such as by a broken fairy light bulb in the circuit therebetween.

Abstract: A circuit tester for both 14-volt and 42-volt automotive electrical systems includes a housing with a probe tip at one end and a ground connector at the other end. A battery-powered voltage detection circuit in the housing includes a plurality of comparators, each having one input connected to an input signal from the probe tip and a reference input connected to a tap of a tapped voltage divider providing plural reference signals having amplitudes respectively corresponding to industry-standard voltage levels, the comparators being arranged in two groups respectively corresponding to 14-volt and 42-volt automotive systems. Series-connected LEDs have their cathodes respectively connected to the outputs of the comparators, and are arranged for respectively being viewed through apertures in the housing arranged in two separate rows. The interconnections are such that only one LED at a time is illuminated, i.e.

Abstract: An electrical connection brush and tester assembly for cleaning electrical contacts to facilitate the flow of electrical current and verify the presence of a voltage at a specified contact. The electrical connection brush and tester assembly includes a handle, a testing rod extending from the handle, a grounding clip, an electrical wire extending between the testing rod and grounding clip, a testing lamp positioned on the handle and illuminated when electric current flows through the testing rod and grounding clip, and a plurality of bristles coupled to the handle.

Abstract: A method of reconizing a fault current in a control unit and to a control unit having a circuit for recognizing the fault current. According to the invention, a current flowing into the control unit which could cause the control unit to be damaged or to operate incorrectly is detected and a fault signal is produced depending on the current detected, the fault signal causing the load or the current supply for the control unit to be switched off, for example.

Abstract: A fault indicator contained within a protective equipment closure of the type used to house pad-mounted components of a power distribution system detects the occurrence of a fault current in a monitored conductor and provides a light indication thereof. The fault indicator includes a circuit monitoring module, having an integral fault indicator flag module, and a remote fault indicator light module. A status-indicating flag is rotatably mounted in the integral fault indicator flag module. The flag is positioned in either a reset indicating position or a fault indicating position by a magnetic pole piece, which is magnetized in one magnetic direction or the other by momentary application of a current in one direction or the other to an actuator winding on the pole piece.

Abstract: A wiring test assembly for validating and troubleshooting electrical problems with vehicle wiring assemblies for trailers. The wiring test assembly includes a housing with a bottom portion hingedly coupled to a top portion, a plurality of indicator lamps coupled to an exterior surface of the housing, and a wiring harness coupled to the plurality of indicator lamps and adapted for coupling to a trailer wiring connector.

Abstract: A fault indicator for detecting the occurrence of a fault current in a monitored conductor and providing a light indication thereof includes a rotatably mounted indicator flag. The flag is positioned in either a reset indicating or a fault indicating state by a magnetic pole piece, which is magnetized in one magnetic direction or the other by momentary application of a current in one direction or the other to an actuator winding on the pole piece. A magnetically actuated reed switch in an auxiliary magnetic circuit comprising an auxiliary pole piece magnetized by the actuator winding and a bias magnet magnetically aligned to oppose the reset magnetic orientation and reenforce the trip magnetic orientation of the magnetic pole piece closes upon occurrence of the fault current to connect an internal lithium battery to an LED visible from the exterior of the fault indicator housing.

Abstract: A circuit testing device includes a handle with a hollow interior, a conductive probe projecting from one end and a removable cap with a wire and clamp projecting from the opposite end A subassembly retained within a counterbore in the handle includes a polarity sensitive buzzer and light in a parallel circuit configuration whereby the device is useful for determining polarity, circuit continuity, and battery drain.

Abstract: A current detector/indicator for DC has a transistor (1) and an LED (2). They are arranged so that current flow through the LED causes the transistor to conduct, shunting excess current away from the LED and through the transistor. For AC, the circuit can be doubled, with transistors and LEDs arranged with inverse polarity. A triac (15) may supplant the two transistors, with parallel, opposed LEDs (16) in its gate circuit.

Abstract: The voltage detection stick comprises an elongate and hollow casing member. A tip is attached to the casing member and has a first leg and a second leg protruding outwardly from the tip. A cavity is defined between the legs. An antenna is disposed within the casing member for sensing a voltage and transmitting a detection signal when an electrically conductive member is disposed in the cavity. An antenna extension is removably attachable within the cavity for increasing the sensitivity of the antenna.

Abstract: A line locating device and method that is capable of determining the location of a line even when a significant amount of transmitted signal is coupled to neighboring lines. A device according to this invention includes a transmitter that couples a transmitted signal onto a metal line where the transmitted signal is a first signal having a carrier frequency modulated with second signal of a lower frequency. The device also includes a receiver that receives a received signal from the metal line and evaluates the signal in terms of period and polarity to determine an incoming signal or an outgoing signal. The receiver addresses an appropriate signaling unit in response to the incoming signal or the outgoing signal.

Abstract: An apparatus and method for performing an auto-ranging function in electronics test equipment monitors both the RMS value and the peak value of the input signal to be measured. In the subject system, a peak signal measurement which exceeds the dynamic range of the currently-selected range will cause selection of the next higher range. A peak signal measurement which would exceed the dynamic range of the next lower measurement range, will prevent selection of the next lower range when the RMS value would otherwise have caused that selection. A peak signal value which does not exceed the dynamic range of the currently-selected measurement range, or the dynamic range of the next lower measurement range will allow control of measurement range selection to be determined by the RMS value of the input signal.

Abstract: A power supply interface device for supplying 110 volt power to an electrical device.

Abstract: A circuit test light includes a reel-shaped housing formed of a light-transmitting material, with a light source disposed in the hub of the reel and connected to the proximal ends of two elongated test leads, the distal ends of which are respectively connected to connector assemblies. At least one of the connector assemblies includes a base connector and a plurality of adapter connectors selectively connectable to the base connector for use with different types of test terminals. The leads can be wound around the hub of the reel for storage when not in use, being retained in place by a suitable strap.

Abstract: A fault indicator contained within a protective equipment closure of the type used to house pad-mounted components of a power distribution system detects the occurrence of a fault current in a monitored conductor and provides a light indication thereof. The fault indicator includes a circuit monitoring module, having an integral fault indicator flag module, and a remote fault indicator light module. A status-indicating flag is rotatably mounted in the integral fault indicator flag module. The flag is positioned in either a reset indicating position or a fault indicating position by a magnetic pole piece, which is magnetized in one magnetic direction or the other by momentary application of a current in one direction or the other to an actuator winding on the pole piece.

Abstract: A device for testing a conductor for the presence of high AC voltage includes a voltage detection circuit connected to a probe assembly, preferably designed for insertion in the access bushing of an underground electrical transmission or distribution equipment. The probe assembly includes an elongated tubular insulating housing with a conductive probe at one end and a threaded connector at the other end for connection to the detection circuit. A high resistance, preferably several megohms, is connected in series between the tip and the connector and is preferably comprised of a plurality of series-connected resistors encased in a heat shrink tubing.

Abstract: A system for testing an arcing fault detection system in an electrical distribution network having a line conductor carrying an electrical signal between a power source and a load, the arcing fault detection system including a sensor coupled to the line conductor for monitoring the electrical signal and generating a sensor signal representing the electrical signal, the arcing fault detection system generating an arc-indicative signal in response to the sensor signal having characteristics indicative of an arcing fault. The testing system couples the sensor to a test line simultaneously with the line conductor and periodically produces a test signal on the test line. The sensor simultaneously monitors the test signal and the electrical signal and produces a sensor signal representing both the test signal and the electrical signal when the test signal is present on the test line.

Abstract: A low error, switchable measurement lead detect circuit (9) for providing accurate current measurement readings and reducing susceptibility to false measurement lead detections due to leakage current is described. A gate (14) that receives an input select voltage Vs selectively connects either a supply voltage, Vd, or ground to the input of a voltage divider (13). Vd is connected during a measurement lead detection mode of operation or open fuse detection mode of operation, and a ground is connected during a current measurement mode of operation. During the measurement lead detection mode of operation, if the pin of a measurement lead is present in a split jack (12), the voltage divider (13) divides the supply voltage, Vd. Conversely, if no measurement lead pin is present in the split jack (12), the output voltage, Vo, of voltage divider (13) equals the level of Vd.

Abstract: An IC card system has, at least, an IC card having a first set of terminals and an external unit having a second set of terminals. The IC card has a detector for detecting a contact condition between the first and second sets of terminals, a controller, and an internal circuit such as an EEPROM. If the detector determines that the contact condition is faulty, the controller completes a given process, and then, stops the operation of the internal circuit. If an access operation to the internal circuit is in progress when the detector finds contact fault, the controller does not stop immediately and continues to complete the access operation, to prevent the writing or reading of erroneous data. The present invention also provides an IC card for the IC card system and a semiconductor IC incorporated in the IC card.

Abstract: A load sensing circuit detects an input load signal across a transformer based on changes in electric current conducted through a primary winding of the transformer. A triangle wave signal is provided to the primary winding of the transformer to induce a corresponding signal at a secondary winding of the transformer. The signal at the secondary winding varies as a function of the input load signal to effect corresponding changes in the electric current conducted through the primary winding. An output circuit provides an indication of the value of the load signal based on the current conducted through the primary winding.

Abstract: Nonintrusive tools for testing power and continuity of AC circuits and wiring. Each tool has a conductive probe extending therefrom that is coupled to a positive terminal of power source or is electromagnetically coupled to a coupling wire that is coupled to the power source. A switching/amplifying device is coupled in series with an indicator between terminals of the power source. A contact is coupled to a switching terminal of the switching/amplifying device that is used to operate the tool when touched by a user. An external coupling device having two electrically isolated wires that are twisted around each other to provide electromagnetic coupling therebetween may be employed when the coupling wire is not used. Physical touching of the contact by the user activates the tool. Once the user activates the tool, the probe may used to directly contact “hot” AC terminals or contact a gel placed on unexposed wires to enhance operation of the tool to determine the presence of power or continuity.

Abstract: The method of this invention provides a means for altering commonly available inductive voltage detector instruments into dual sensitivity test instruments. By shielding the sensor probe with a metallic material, the probe is made to be unresponsive to energized conductors in near proximity when the shield is grounded by finger contact. A single probe window is provided so that when grounded, the instrument will respond to an energized conductor in only the probe window area allowing testing of single conductors in wire bundles. When ungrounded by the electrician's finger, the instrument reverts to normal sensitivity. Provision is made for safety by isolating the metallic shield from contact with energized conductors. The method may be employed by means of a demountable accessory or incorporated into the test instrument during manufacture.

Abstract: A self-contained unit intended primarily for tracing the circuit connection between an electrical outlet or lighting receptacle and its corresponding circuit-breaker. The preferred embodiment includes a housing, a male two prong electrical plug, and a sound-producing means. A second embodiment includes a male three prong electrical plug. A third embodiment incorporates a momentary switch which permits testing of a ground fault interrupt across either a hot wire and a neutral, or across a hot wire and the ground. Adapters are used to temporarily adapt bare wires or a lighting receptacle to a female plug so that the device may be used.

Abstract: The voltage detection stick comprises an elongate and hollow casing member that has a front and a back. A tip is rotatably and removably attached to the front of the casing member and a sensor is disposed within the casing member for sensing the presence of a voltage when the sensor is positioned adjacent an electrically conductive member. The casing member has an indicator and an integrated circuit entirely disposed within the casing member for receiving a signal from the sensor and transmitting the signal to the indicator. A power source is disposed within the casing member for powering the sensor, the integrated circuit and the indicator.

Abstract: A system for warning regarding the presence of manually attached grounding contacts (21) on high voltage conductors (3), comprises a) a naked additional conductor (1) close to the high voltage conductor (3), however spaced therefrom, and with an ability to be clamped resiliently to contact with the high voltage conductor (3) when the grounding contact (21) is attached; and b) a warning device (20) having connection means (4, 5) to the high voltage conductor (3) and to the additional conductor (1). The warning device has, in a part (24) arranged near the high voltage conductor (3), equipment for sensing whether the additional conductor (1) has been brought to contact with the high voltage conductor or not, and for transmitting a signal regarding this condition to another part (26) of the warning device which is remote from the high voltage conductor, preferably at ground potential. From this part (26) the signal can be transmitted to an operation central.

Abstract: A spiking tool for spiking high voltage underground power lines includes a safety shield to protect the operator of a shotgun stick from the flame and heat emitted when a hot power line is spiked. A first embodiment of the tool includes a tubular sleeve for encasing a length of power line. The tubular sleeve has a slot therein through which a power line can be introduced into and encased within the tubular sleeve and a spiking assembly with a grounded spike made of an electrically conductive material for penetrating the insulating casing of and making contact with wiring within a power line housed within the tubular sleeve. A second embodiment of the tool includes a shield plate mounted on and extending outward from the shaft of a shotgun stick intermediate a first end of the stick which engages a spiking clamp and a second end of the stick held by the tool operator.

Abstract: A voltage and continuity tester consists of a positive probe, a negative probe, and a valve finder probe. An AC/DC activated loud buzzer is coupled across the positive probe and the negative probe. In the preferred embodiment, the valve finder probe is coupled to the negative probe via a diode. In operation, the voltage and continuity tester is a simple, convenient and affordable diagnostic tool used to systematically troubleshoot common problems with irrigation and other systems. The loud AC/DC activated buzzer allows diagnosis of system failures from a remote location and eliminates the need to stay within close visual range for interpretation of test results. When used to test irrigation systems, the valve finder probe allows a user to quickly and easily locate any valve in the system. In the preferred embodiment, the positive probe and the negative probe include piercing connectors that break through the insulation of a wire and directly contact the wire without having to cut the insulation.

Abstract: A combination ground and power source circuit tester device includes a cylindrical plug with a cone-shaped end that fits into a vehicle accessory receptacle. An attached body member engages the plug and retains first and second radially extending contacts that function to provide a connection with conductive studs that attach to leads to a circuit. A light bulb indicating that the circuitry is powered is retained in the body member and in a parallel circuit with the contacts.

Abstract: In this micro-controller-based line voltage meter/monitor instrument, an AC signal-under-test is sensed from the line voltage via a broadband isolation transformer, and processed to provide RMS and fast peak signals. These are A/D converted in the micro-controller in a sampling process synchronized from a zero-cross signal detected from the AC voltage-under-test. An LED (light-emitting diode) display with 40 LED segments provides resolution of one volt RMS per LED step/segment, and is color-coded to overlay the CBEMA nominal limits. RMS values ranging from 95 to 135 volts are indicated on a bar graph, and fast peak values ranging from 120 to 500 volts at the waveform crest are indicated by the selected LED cell flashing at a 1 Hz rate, with selectable peak hold time. An internal real time calendar/clock enables accumulation of time-related data regarding the ongoing quality of the power line voltage levels.

Abstract: A method of determining whether an electrolytic capacitor is properly connected or reversed in an electronic assembly. In a first embodiment, a non-contacting probe is placed near but not touching the body of the device under test (DUT). One terminal of the DUT is driven by a stimulus (voltage source or current source) while the other terminal is connected to a reference voltage. A voltage is measured at the probe relative to the reference voltage and the device is properly oriented if the measured voltage exceeds a predetermined threshold. In a second embodiment, current through the probe is measured instead of voltage at the probe. In a third embodiment, a non-contacting probe is placed near but not touching both leads of the DUT. Each DUT lead is alternately driven by a stimulus and alternately connected to a reference voltage. For each of the two lead test configurations, a voltage at each DUT lead is measured and current through the non-contacting probe is measured.

Abstract: A test system for distinguishing a particular AC distribution circuit interrupting device from among a plurality of AC distribution circuits interrupting devices. The test system comprises a transmitter for placing an identification signal on an AC power distribution circuit and a receiver for detecting the identification signal. The transmitter comprises means for generating an FM modulated identification signal, and means for coupling the identification signal to the AC power distribution circuit. The receiver comprises preselector means for selecting a predetermined band of frequencies for further processing, first detector means for detecting a signal within the predetermined band of frequencies, second detector means for detecting a modulating signal, and processor means for processing indications from the first and second detectors, and for activating a discernible indication of receiver operation.

Abstract: An electrical circuit finder has a transmitter which is plugged into one of the circuits of a building's electrical system and a receiver which is used to identify other elements of the circuit such as a circuit breaker, fuse, switch, electrical device or outlet. The transmitter induces in the circuit a high frequency current signal which is modulated at a lower frequency. The receiver, including a sensor wand and a receiver housing, is tuned to inductively detect the high frequency when placed in the magnetic field of the circuit and to produce visual and audible signals to the user which vary in intensity according to the detected signal. The user can thereby use his or her visual and/or audio senses to associate a circuit element proximate to the receiver with the circuit element connected to the transmitter.

Abstract: An indicator for mounting on a power cord (FIG. 3) for almost instantaneously indicating the presence or absence of a single-phase AC voltage potential on a monitored power cord for a grounded AC power distribution system. The indicator comprises a housing (16, 18, 20, 26), an electronic display (10), a static suppression resistor (12), a first conductive element (14) in physical proximity to the monitored power cord, and a second conductive element (22) meant to be touched by a human being to provide a visual indication on the electronic display (10) of the presence or absence of a voltage potential on the monitored conductor or power cord. The hot conductor being part of a power cord is capacitively coupled (FIG. 1) to an electronic display (10) in parallel with a static suppression resistor (12). A current flow due to the capacitive coupling between the hot conductor and first conductive element (14) causes a voltage drop across the display (10) and the resistor (12).