Abstract: A loss of neutral or ground protection circuit is disclosed which uses a simple capacitive circuit which discharges through the neutral or ground leads in normal conditions, and in the event of loss of neutral or ground charges sufficiently to trip a circuit breaker. The protection circuit may include other circuits such as ground fault detection circuits and may be in a one or three phase system. By virtue of the fact that a capacitive circuit is used to trip the circuit breaker, an inherent time delay is involved and thus the circuit breaker will not be tripped as a result of a momentary loss of neutral or ground. This is particularly important where continuity of operation of a load is important.

Abstract: Apparatus for protecting electrically operated devices from damage as a result of penetration of moisture has an electric switch or a normally intact conductor, and an explosive or ignitable actuator which initiates an opening or closing of the switch or at least partial destruction of the conductor when operated by one or more sensors which detect the presence of moisture in or close to the electrically operated device. The explosive actuator can be used to clear the path for movement of a movable switch contact from open to closed position or vice versa, or to break up a conductor when ignited or otherwise operated in response to a signal from the moisture sensor or sensors. A combustible actuator can employ a flash light whose envelope confines a portion of a conductor and further contains a combustible material serving to generate heat on ignition in response to a signal from the sensor or sensors whereby the heat destroys the integrity of the portion of the conductor in the envelope.

Abstract: The invention comprises a self-proving vehicle grounding system for placing the ground of a transportation vehicle at the same voltage as the ground of a loading rack and is intended for use in conjunction with an overfill protection system. The overfill protection system comprises a sensor unit on the vehicle and a base unit on the rack for disabling the loading equipment when the sensor detects overfill. The invention comprises three parts, a controller unit coupled to the filling station ground, a grounding bolt unit which is coupled to the transportation vehicle and a multi-conductor cable. The controller unit comprises a signal generator which produces a first electrical signal and a signal detector which, when it receives a specified second electrical signal at its input, enables the pumping equipment of the filling station.

Abstract: A control module is connected to a table strip having a number of jacks. A sensor probe which consists of a sensor detector and a sensor cable has at the end of the cable a plug which is connected to the table strip jack. Each sensor cable is provided with a continuity circuit and a floating circuit such that cutting of the cable or shorting of the cable will energize an indicator circuit and an alarm annunciator in the control module.

Abstract: A purse includes a wavy wire fully distributed on a purse casing and an alarm formed in the casing whereby upon a cutting or breaking of the wire by a thief or pickpocket, the disconnection of wire will actuate the alarm sounding for preventing its robbing, and also includes an emergency switch which is operated by pulling a handle or belt of the purse to disconnect the wire for sounding the alarm.

Abstract: A device for remote metering, comprising a meter (4) for measuring a consumption, a transmission circuit for transmitting information relating to quantities consumed, and consisting essentially of a modulating circuit (5,6) and of a bifilar line (3), and a counter circuit for counting sets of information. The modulating circuit comprises a capacitive network (6) and at least one switch (5) which is actuated by the meter and which is capable of modifying the capacity of the capacitive network. The device further comprises a circuit (7,14) suitable for evaluating the value of the capacity of the transmission circuit, and thus for distinguishing two states of the modulating circuit and one state of a fault in the line. Such a device is, in particular, usable for the remote metering of a consumption of gas or of electricity.

Abstract: An apparatus for testing a cross-coil instrument having a pointer, a sensor for sensing a condition to produce a sensor signal indicative of the sensed condition, and a converter coupled to the sensor for converting the sensor signal to a deflection of the pointer. The apparatus comprises a fault detector coupled to the sensor for detecting a disconnection fault to produce a command signal, and a test signal generator responsive to the command signal for generating a predetermined test signal to the converter, thereby moving the pointer to a predetermined position. The operation accuracy of the cross-coil instrument may be checked from the difference between the actual and predetermined pointer positions when a connector provided in a signal line between the sensor and the fault detector is pulled out.

Abstract: A multi-function tester (10) for testing electrical continuity and detecting the presence of various types of voltages comprises a bistable flip flop (14) having set and reset input terminals (2, 6) which are driven by voltage changes thereat to change the level of voltage appearing at an output terminal (3), with the set input terminal being coupled to a voltage source (12) through a set resistor (30) and being coupled to a common terminal (26) through a TMOS FET switch (16). An LED (32) is connected between the flip flop output terminal and the common terminal. A storage switch (18) couples and decouples the set and reset terminals.

Abstract: An electrostatic system monitor and method for monitoring the operation of static control equipment such as conductive workbench and floor mats, conductive wrist straps, and the integrity of ground connections and soldering irons and to activate indicators and alarms when the static control equipment deteriorates or malfunctions by having resistances outside of predetermined values and ranges of resistance. The electrostatic system monitor also provides for the detection of unsafe voltage potentials on soldering irons, and for a surface resistance probe for measuring the surface conductivity of conductive surfaces of the static control equipment.

Abstract: A rectangular sheet of backing material has a first surface and a second surface and a conductive wire which is mechanically coupled to the first surface of the rectangular sheet of backing material. A work of art includes a decorative frame and a stretcher frame which has a first surface and a second surface and which has a rim disposed on its first surface along its peripheral edge and a painting canvas which has a front side and a back side. The stretcher frame includes a plurality of individual frame members which permit each of four peripheral edges of the front side of the painting canvas to be folded over so that the folded over peripheral edge is adjacent to the back side of the painting canvas. The dimensions of the stretcher frame may be expanded in order to stretch the painting canvas. The stretcher frame and the painting canvas are mounted on the decorative frame. A plurality of staples secure the conductive wire to the painting canvas, the stretcher frame and the decorative frame.

Abstract: A self-contained alarm system for a boat outboard motor connected to a boat transom by clamps is easily retrofit onto an existing boat. A housing of tough non-conductive material (such as polycarbonate) contains a power source (such as a battery) and a signalling device (such as a horn or lights). The housing includes a hub and a pair of arms, which are pivotal with respect to each other about the hub, or the arms can be sliding members, sliding relative to each other. Electrical contacts are provided adjacent the end of one or both of the arms, the contacts engaging clamp pads. If the clamp pads are moved out of operative engagement with the contacts, the battery activates the signal device. A circuit for sensing an open circuit condition may interconnect the signal and battery may be provided, or the contacts may be designed so that a closed circuit actuates the signal.

Abstract: Positive assurance of correct connection, in supplying electrical utilization equipment from a current source, is provided when it is critical to safety and particularly when receptacle outlets are used or a fixed wiring installation required which may be subject to wiring error. An electromagnetic relay is employed to prevent equipment use and to provide audible indication in the event of hazardous connective error such as reversal of ungrounded and grounded neutral conductors and the omission of a grounding connection. The relay may be one that is also otherwise controlled for on-off power switching.

Abstract: A malfunction detector is connected to switches provided in a machine, such as a punch press, for actuation when a malfunction occurs. The detector is capable of supplying an alternating current test signal to the switches and determining whether the resistance of the switches to the test signal is greater than or less than a threshold value. The test signal preferably has a frequency which is equal to mains supply frequency or a harmonic thereof and the malfunction detector preferably only responds to changes of state of the switches during specific time windows.

Abstract: In an electrical appliance having an electrically conducting housing, defective grounding of the housing may result in a dangerous situation for the user. To prevent such a dangerous situation, the appliance, also having an internal, load circuit, is provided with a safety connector device, which connector device comprises an electric plug having two power contacts through which the load circuit is energized, and two auxiliary contacts. The two latter, auxiliary contacts are respectively connected to two separate points of the housing so that they are interconnected together through an interconnecting circuit including the electrically conducting housing of the appliance. One of the two auxiliary contacts is connectable to a ground for grounding the housing whereby a disconnection of the ground from the housing can be detected by sensing a discontinuity in the interconnecting circuit.

Abstract: A security device (10) for protecting sensitive data stored in a resettable memory (110) includes a housing (11) formed of six ceramic plates (P1-P6) each having provided thereon a pair of thin film conductive path segments arranged in a meandering configuration. The thin film conductive path segments are joined together by interconnection devices (30) each including a pair of ceramic studs (e.g. K9, K10) having conductive areas (34, 38) thereon connected by an interconnect block (e.g. N5), thereby forming two complete thin film conductive paths (WMA, WMB) which meander in a closely spaced, parallel manner over the entire inner surface of the housing (11). Interrupting or short circuiting the thin film conductive paths (WMA, WMB) causes reset means (130) to reset the resettable memory (110) thereby erasing the data stored therein.

Abstract: A security system includes a plurality of sensors each capable of providing a detection input signal adapted to cause activation of the alarm system, a circuit for inhibiting activation of the alarm system as a result of a first detection input signal, and a circuit for removing the inhibition and allowing activation of the alarm system in response to a second detection input signal from any one of the sensors, including the sensor that provided the first detection input signal. A first alarm device is located essentially indoors on the premises to be protected and a second alarm device is located outdoors on the premises to be protected. The inhibition circuit allows activation of only the indoor alarm device, but a further detection input signal from one of the sensors within a predetermined time activates the outdoor alarm device.

Abstract: A load monitoring, indicating, and alarm system monitors electrical continuity through an AC electrical load coupled in a first electrical line with an electrical indicator such as an indicating lamp in a second electrical line coupled in parallel with the first electrical line. A first AC electronic switch such as a triac is coupled in series with the indicator in the second electrical line. The actuating gate of the first AC electronic switch is coupled to the first electrical line. The first AC electronic switch is therefore conducting and the indicator lamp on when there is electrical continuity through the load and power is being supplied to the load. A reactance control component is coupled in series with the load for adjusting the phase angle of gate current to voltage delivered to the gate terminal of the first AC electronic switch. The reactive component may be a second AC electronic switch coupled in series with the electrical load in the first electrical line.

Abstract: A differential transceiver transmission line integrity detector detects both open and short circuits in the transmission lines. The two transmission lines are terminated at both ends by selected impedances. A driver coupled to each of the transmission lines drives the lines with data signals. Signal levels on the lines are detected and compared with expected levels to generate line integrity indications. Both open and short conditions are detected and indicated by the line integrity indications.

Abstract: An apparatus is provided for self-monitoring a communication circuit incorporating a differential driver for malfunctions with a malfunction detector located remote from the driver. The malfunction detector monitors the state of signals received at the remote location on a pair of lines coupled to the driver. Preferably, the detector includes a pair of back-to-back light emitting diodes, one of which will emit light so long as the received signals are in opposite states, and neither of which will emit light when the received signals are not in opposite states as will occur during a malfunction. The detector further preferably includes a phototransistor responsive to the diodes to provide a malfunction signal when neither diode emits light. Alternatively, the detector may comprise an exclusive-OR logic gate.

Abstract: A transmitter circuit adapted to be connected to a sensor and generate a 4-20 milliampere signal proportional to the output of the sensor includes a first amplifier which is connected to the sensor and has an output voltage proportional to the sensor output voltage. A predetermined reference voltage is supplied to a reference input of the first amplifier. A second amplifier housing an output voltage responsive to a difference between its input voltages, has its output connected to the gate of an output transistor, preferably a fluid offset transistor. An output resistor is connected between the positive power supply and the source of the output transistor. The output of the first amplifier is supplied to the positive input of the second amplifier and the voltage at the source of the output transistor is supplied to the negative input of the second amplifier. The output current for the transmitter is generated at the drain of the output transistor.

Abstract: The present invention is a circuit for activating a local alarm when a telephone service line is cut. A closed loop circuit is formed by a pair of insulated monitor wires electrically connected at their first ends to a resistor and electrically connected at their second ends to a normally closed circuit of an alarm. The wires are secured to a telephone service line. Shrink tubing encapsulates the wires and the service line together in a single cable. When the cable is cut, thereby severing either or both of the insulated monitor wires as well, the closed loop circuit is opened, thereby activating the alarm. In various embodiments of the invention, circuitry is provided upstream from the cable for signaling a telephone company of a loss of a service line connection. A load or signal is generated by the circuitry and transmitted over telephone service lines. When such a load is detected, proper authorities can be notified of the loss of the service line connection.

Abstract: A filament bypass circuit for use with a string of lamps in series capable of continuing current flow when a lamp in the string fails. Each lamp is provided with a shunt circuit consisting of a series circuit of a diode and a silicon bilateral voltage triggered switch. The switch becomes conductive upon the application of a substantial increase in voltage from the A.C. source and remains conductive until there is an interruption of current flow or current flow drops below its required holding value. The diode insures that during continued operation after a failure there will not be an excessive voltage applied to the remaining lamps, and also serves as an indicator of a failed lamp.

Abstract: A control device for valves and the like, including at least one control switch (13) which is inserted in at least one optical conductor (18,118), and is connected to the valve actuating means in such a manner that it will be automatically actuated (i.e. opened or closed) upon the actuation (i.e. opening or closing) of the valve, thus interrupting the respective conductor (18,118) or re-establishing its continuity. The conductor (18,118) is comprised in a warning and/or control circuit, and the opening or the closing of said switch (13) generates a signal which may be utilized, for example, to detect and/or to record the actuation of the valve and/or to activate a television inspection system. The control switch (13) is formed by a connector for optical fibre and comprises two complementary and co-axial connector members (14,15) one of which (14) is stationary and the other of which (15) is movable axially and is urged towards one of its end positions (i.e.

Abstract: A static relay for low DC voltages includes output transistor (T.sub.s) with its emitter connected to an output terminal supplying a load (Z) further connected to a common supply terminal. The base of the output transistion (T.sub.s) is supplied via the main current path of a current injection transistor (T.sub.i) acted upon via a control electrode. The current injection transistor (T.sub.i) is supplied with an auxiliary voltage (V.sub.aux) which is higher than the voltage (V.sub.bat) feeding the output transistor (T.sub.s). A detection transistor (T.sub.c) has its emitter-base path, which includes a base resistor (R.sub.b), connected parallel to the base-emitter path of the output transistor (T.sub.s) and delivers at its collector a detection signal representative of the state of the load (Z).

Abstract: An electrical apparatus for monitoring electrical continuity includes a number of input circuits each associated with a respective arm of a multi-phase rectifier circuit the continuity of which is to be monitored. Each input circuit includes a comparator which generates a train of pulses P while an input current persists in the arm. If a discontinuity arises in an arm for a first preset interval of time a monostable in that arm generates a first trigger signal. If the discontinuity persists for a further preset interval of time another monostable, common to all the arms, triggers an alarm via a bistable circuit.

Abstract: A signalling circuit which outputs reference potential at either a first or second output, dependent on an input signal. The signalling circuit operates reliably in a large range of operating voltage with an optimally low power consumption. A constant current circuit and a parallel connection of two current paths fed by constant current are provided in a circuit connected to an operating voltage source. The first and second outputs are respectively connected to reference potential via respective electronic switches controllable by the current of the respective current path. The constant current is switchable from one current path to the other and vice versa, dependent upon the input criteria.

Abstract: A sensor circuit for detecting a ground fault in devices that eliminate or prevent static electricity and for producing appropriate alarm signals to indicate an undesirable ungrounded condition. In particular, the sensor circuit includes means for monitoring a ground-fault system by using a wrist strap monitoring circuit, a proximity monitoring circuit and at least one surface monitoring circuit. The wrist strap monitoring circuit and the surface monitoring circuits are used to detect the status of a grounding connection between an operator and/or a surface at a work station and a ground potential. The proximity monitoring circuit is used to determine whether an operator (or another person) is in proximity to the work station. A logic circuit means detects the status of the aforementioned monitoring circuits and selectively activates an alarm means if a fault condition exists.

Abstract: A self-contained alarm system mounted in a housing is adapted to be mounted between the clamps of an outboard motor and the transom of a boat. The clamps of the outboard motor are electrically coupled to circuit means in the housing of the alarm system through electrically conductive sensor members in the housing. The circuit means acts as a discontinuity or open circuit detector. When a clamp of the outboard motor is backed off, either intentionally or accidentally, the circuit means electrically detects the change of resistance and activates a sound device located in the housing.

Abstract: A safety line 20 of an aerial ropeway transport installation 10 comprises in one of the stations a safety generating unit 22, which emits a square wave AC signal on the line.In the opposite station the line 20 is earthed by means of a diode 24. The safety generating unit 22 includes a measuring device of the positive and negative voltages at the line terminals to distinguish between a line break and a line short-circuit.A localizer indicates the location of the fault.

Abstract: A glazing unit alarm system includes a light transmitting electrically conductive coating which extends over at least most of the area of a glazing panel and forms part of an alarm circuit. Changes in the resistance of the coating, occasioned by breakage or attempted breakage of the glazing panel, trigger an alarm. The alarm system is characterized by the electrically conductive coating being constituted by an emissivity coating, e.g. a low-emissivity coating, for modifying the effect of incident electromagnetic radiation on the glazing panel over different wavelengths.

Abstract: A fail safe circuit is provided in a salinity monitor having a salinity indicating panel for visually presenting salinity levels and a salinity cell for sensing salinity levels. The salinity cell is electrically connected to the salinity indicating panel by a plurality of salinity cell leads which supply electrical signals to the salinity indicating panel for indication of salinity levels. The fail safe circuit enables an alarm when a salinity cell lead becomes disconnected from the salinity indicating panel. Also, a back-up circuit is provided for enabling an alarm should the fail safe circuit become inoperative.

Abstract: An electric element breakdown detector includes an electric element (5: 5a: 106: 132: 172) connected in series with a switching element (6: 6a: 116: 116a: 171) which define a series connection. A processing circuit (40: 110: 174) produces a control signal to the switching element to control on and off operation of the switching element, so as to control the current flow through the series connection. A comparator (10: 119) is provided for comparing a voltage at one end of the electric element with a reference voltage produced from a reference voltage producer (12: 121, 123), and generates a result signal representing the result of the comparison. The result signal is fed to the processing circuit. The processing circuit detects the condition of the series connection by the detection of combination of the control signal and the result signal.

Abstract: An optical indicator apparatus includes an optical output device for producing a light output in response to an electrical input thereto, a hollow housing for supporting the optical output device relative to another device to permit viewing of light output by the optical output device, electrical input leads extending through at least a portion of the housing for receiving such electrical input and coupling the same to cause the optical output device to produce an output indicating receipt of such electrical input, and seal material for sealing in substantially fluid-tight relation in the hollow housing at least part of the optical output device and at least part of the electrical input leads while holding the same in relatively fixed position in the hollow housing.

Abstract: An electrostatic system monitor and method for monitoring the operation of static control equipment such as conductive workbench and floor mats, conductive wrist straps, and the integrity of ground connections and soldering irons and to activate indicators and alarms when the static control equipment deteriorates or malfunctions by having resistances outside of predetermined values and ranges of resistance. The electrostatic system monitor also provides for the detection of unsafe voltage potentials on soldering irons, and for a surface resistance probe for measuring the surface conductivity of conductive surfaces of the static control equipment.

Abstract: An apparatus to monitor a circuit in which an AC voltage source is connected to a plurality of paralleled current consuming loads, such as heaters, including a reactive load in parallel with the current consuming loads at a point in the circuit more distant from the voltage source than any of the current consuming loads being monitored, a phase shift detector connected to the current consuming loads and at a point in the circuit between the voltage source and the nearest current consuming load being monitored, the phase shift detector being sensitive to the shift in current phase induced by the reactor load, and an alarm connected to and actuated by the phase shift detector which provides a warning when the phase shift induced by the reactive load is lost, indicative of a failure in the circuit.

Abstract: Apparatus which can be embodied in an electronic wristwatch monitors the integrity of a wrist strap ground. An input terminal to which a known ground is coupled is provided. An oscillator produces a fixed frequency which is mixed with a signal from the input terminal to provide a composite signal. The composite signal is coupled to one input of an exclusive OR-gate. The other input of the exclusive OR-gate is coupled directly to the output of the oscillator. The output of the OR-gate is processed to produce an output signal indicative of the phase relationship between the oscillator output and the composite signal. When the input terminal is grounded, the phase relationship between the oscillator output and the composite signal changes, resulting in a change in the output signal which can be used to trigger an indicator (e.g., visual display and/or aural alarm) to indicate to a user whether he or she is properly grounded.

Abstract: An alarm system and assembly including one or more base elements specifically structured for positioning on the interior of a jewelery-type display case and including a circuit means having an extended conductor interconnected in series with an alarm assembly and power source and further interconnected with a plurality of tray elements mounted on an exposed display platform to the extent that movement or actual removal of any of the tray elements will cause a break in the circuitry through separation of first and second contact pairs associated with the conductor means which in turn causes an activation of the signal assembly so as to provide a warning to attendant or merchants in the vicinity of the display case. Further, the signal assembly will be activated upon relative movement and/or displacement of the plurality of base elements independent of any displacement of tray elements.

Abstract: A circuit for detecting a disconnected input signal line to an integrated circuit includes an emitter follower stage having a transistor whose base is connected to the monitored input signal line, the input signal being transferred to the integrated circuit through the base-emitter path of the emitter follower. A current source transistor connects to the emitter of the emitter follower transistor, the base of the current source transistor being coupled to a voltage supply and a detector circuit, the detector circuit functioning to detect the base-emitter voltage of the current source transistor. The detected voltage provides an indication of whether or not the input signal line is connected to the base of the emitter follower transistor.

Abstract: This on/off power detector includes an input connected directly to a power source and input connected to the power source through a switch. The detector compares voltages on the two inputs to produce an output signal when the voltage on the switched input drops a predetermined amount below the voltage on the unswitched input, which is indicative of the switch being open. The detector is strobed on and off and only compares the input voltages to provide the output signal when it is in its strobed on condition.

Abstract: Apparatus for detecting the position of a probe relative to a workpiece, for example probe contact with the workpiece, is disclosed. The apparatus includes a transducer for converting probe contact to an electrical signal and a plurality of light emitting semiconductors for wirelessly transmitting an indication of the occurrence of the signal via infrared radiation. The apparatus is particularly suitable for operation with a mechanical switch type probe transducer. The apparatus is easily adapted to transmit the occurrence of probe contact by either amplitude modulation or frequency modulation of the emitted infrared radiation.

Abstract: An automated multiple thermocouple testing device determines short and open circuits in a thermocouple system. The thermocouple system has a plurality of temperature probes, each probe has a first thermocouple and a second thermocouple. The device applies a direct current voltage to the first thermocouple to cause heating in the second thermocouple and then reads the temperature response of the second thermocouple. The first thermocouples have a common lead and the second thermocouples are connected in two parallel groups. The temperature output of the second thermocouple is digitized and read by a computer. These readings are compared to criteria which determines if there is an open circuit. Before the open circuit test is applied, the device also determines which thermocouple probe has a possible short circuit. This device can automatically test for short and open circuits in a thermocouple system within a few minutes without the necessity of removing the probes from their installed position.

Abstract: Circuit arrangement for fault locating in conjunction with equipment for the trunk feeding of electrical loads by means of dc series feeding in which the trunk supply circuit is equipped with cross branches conducting only for currents in the direction of a test current. In such a circuit arrangement it is possible to indicate the results of the fault locating in a simple manner. Towards this end, one window discriminator for each load is provided in the supply point. This circuit arrangement can be used advantageously in communications equipment having trunk fed waystations.

Abstract: A contact monitor and annunciator unit for providing a persistent warning in the event one of a selected number of event monitoring circuits associated with a mobile refrigeration system opens. The unit includes a number of warning circuits that are electrically isolated from the monitoring circuits by optical isolators and a separate power supply so that the initial cause of a shut down due to abnormal operating conditions can not only be annunicated but also differenciated from a shut down caused by a momentary power failure.

Abstract: A monitor for sensing any break in electrical continuity between a body and earth when the body is coupled to earth by way of a grounding tether used to prevent build-up of static charges on such body. The monitor includes an oscillator circuit for generating A.C. output voltages which are adapted to actuate an alarm. Body capacitance and resistance are coupled by way of the tether across an impedance network either in the tuned circuit determining oscillator frequency or in the output load thereof whereby the resistance or inductance of the impedance network provides the path to ground for the body through its tether. With body capacitance and resistance components of the total impedance, variable elements in the impedance network are adjusted to diminish the circuit output voltage below the threshold voltage required to actuate the alarm when continuity exists while developing an output voltage level sufficient to actuate the alarm when a break in continuity occurs.

Abstract: A circuit for use in a power supply of the type which regulates the voltage at a load remotely connected to the output of the supply. The circuit allows the voltage at the load to be sensed so that the voltage control loop of the supply can control the load voltage in a relatively accurate manner. The circuit also provides means to detect the breakage of any one of the sense leads.

Abstract: A contactless motion detector responsive to the approach of a ferromagnetic element, including an oscillator with a sensing coil, has an output lead connected to one input of a first Exclusive-OR gate having another input connected to a square-wave generator whose pulses appear in the output of that gate with or without phase inversion depending on the output voltage of the motion detector. These pulses are fed, via an amplifier, to one input of a second Exclusive-OR gate whose other input receives the output pulses of the square-wave generator directly but with a delay compensating a lag introduced by the first gate and the amplifier. In the absence of a malfunction, the inputs of the second gate are energized either cophasally or antiphasally to produce either a low or a high output voltage of substantially constant magnitude fed to a load; in the event of a malfunction interrupting the pulse transmission to either input of this second gate, its output becomes a pulsating voltage.

Abstract: A monitoring system for use with an electrified fence and an energizer (21) therefor, monitoring system being adapted to determine the effectiveness of electric pulses applied to the fence by the energizer (21) and including a voltage sensing device (10) for sensing the voltage of the pulse applied to the fence conductor, a current sensing device (12) for sensing the current in the fence conductor and monitoring device (14) (16) (17) (20) for monitoring signals related to the current and voltage whereby the monitoring device (14) (16) (17) (20) operates an alarm (18) and/or indicates a reading on an indicator (15) when the monitored signals fall outside predetermined ranges of values indicative of lack of fence effectiveness.

Abstract: Electrical systems, especially elongate heating systems, include means for monitoring circuit continuity and/or absence of ground faults. The systems comprise a switching device, e.g. a thermostat, as well as a circuit breaker. When the switching device is on, a relatively high current passes through the circuit and when it is off, little or no current passes through the circuit. In one embodiment, a small controlled residual current flows in the circuit even when the switching device is off, and a current-detecting device signals when a discontinuity causes the current to drop below the expected value for the residual current. In another embodiment, the switching device is placed so that the heater (or other electrical load) is at a positive potential with respect to ground even when the switching device is off, and a ground fault indicator is used to compare the currents in the two legs of the circuit and to signal when a ground fault causes the currents to differ.

Abstract: A security fence system employs a plurality of very thin, high tensile strength, highly stressed wires arranged relatively close together and between each of which is connected an electrical resistance. A voltage source causes a current to flow through the series-connected wires and resistors. An annealed segment can be formed in each high tensile strength wire and located between the points where each wire is attached to the fence posts, to make stretching of the wires without breaking them impossible. A sensing circuit is connected to the fence and includes voltage comparators and potentiometers for providing adjustable triggering levels. The comparators detect when the current flowing in the fence is altered and trigger an alarm if any of the wires are broken, or if any of the wires contact one another. The alarm can be turned off only by normalizing the fence and actuating a reset switch.

Abstract: A data inserting device for a camera arranged to automatically insert data in response to an insertion trigger signal from the camera body includes abnormity detecting means which supplies current to a specific part where such abnormity that hinders the data inserting action tends to occur and is arranged to detect the abnormity by an impedance change occurred at the part, and external display means for displaying the abnormity upon detection thereof by the detecting means.