Abstract: A transformer system couples a control panel with a power line to support two-way communications over the power line. A first transformer steps-down the power line voltage, supplying power to the control panel. A second transformer and associated capacitors provide a low impedance path at the communication signal frequencies and a high impedance path at the power frequency.

Abstract: Methods and apparatus for switching a load between first and second sources is shown to include first and second solid state switches connected to the load. First and second mechanical breakers are connected between the switches and the sources so that each source is connected to the load through a circuit breaker and solid state switch. A controller is connected to sense the voltage from the first and second sources. The controller is connected to the first and second switches and the first and second mechanical breakers. The controller senses the phase difference between the voltages from the first and second sources. The controller causes the first and second mechanical breakers to open and close in response to sensing the phase difference between the sources. The first and second mechanical breakers can include medium voltage vacuum breakers.

Abstract: In order to protect a polarity-sensitive load from a reversed battery assembly, the drain and source electrodes of a MOSFET (or bipolar transistor) device are connected in series with the load and battery and its gate electrode is connected to or otherwise coupled to a node between a battery terminal and the load. If the battery is inserted with correct polarity, the transistor is turned on and inserts its small on-resistance into the circuit. If the battery is inserted with incorrect polarity, the transistor does not turn on, and the polarity-sensitive load is protected.

Abstract: A microprocessor controlled automatic transfer switch is provided with an improved voltage sensing scheme which utilizes an open-delta transformer and a control routine for determining voltage level or phase loss. The invention requires only two transformers for sensing three-phase power. An actuator protection feature is also provided to limit the duration of power applied to and to protect the actuator solenoids on the automatic transfer switch. Also provided are improved diagnostic annunciation features which provide specific information regarding switch position and sensing element and/or actuator malfunction.

Abstract: Disclosed herein is an apparatus for use in an AC power distribution system having a sinusoidal voltage source and a load, the apparatus including a circuit for selectively connecting and disconnecting the load from the source, a circuit for sensing voltage of the source, and a circuit for memorizing a characteristic of the source voltage, prior to the load being disconnected from the source, and for reconnecting the load to the source at a zero crossing point of the voltage sinusoid so that the sinusoid continues cycling in the direction it would have if the load had not been disconnected from the source.

Abstract: A device to prevent reverse current flow includes a diode connected between a power supply and a load. A switching device, connected in parallel with the diode, has a power loss that is smaller than that of the diode. A low-loss current detector, arranged to turn the switching device on and off, includes a DC current detector and a comparator. The comparator compares the detected DC current value with a threshold value for an operating current and generates an output signal that determines when the switching device should be turned on or off.

Abstract: An absolute value circuit according to the present invention has a configuration wherein a switch is connected directly to an output of an amplifier and an output terminal. Owing to this configuration, the absolute value circuit can be realized which is capable of providing full-wave rectification with less distortion.

Abstract: A programmable data link module (32) for use in a time division multiplexing control system (30) having a plurality of modules interconnected by a bus (40) for passing control signals between data link modules on a serial multiplex basis. Each module includes an integrated circuit (80) having signal conditioning circuits (180, 186 and 188) including a programmable hysteresis circuit (126), a power on reset delay circuit (190), a safety input inhibit circuit (220), a clock loss detect circuit (240), a safety output protection circuit (262), a data verifier (260), a polarity selector for a third output terminal (350), an input synchronizer (182 and 184), a combined mode/sync output terminal (110), a multiplex clock output terminal (108), a programming circuit (232) for accepting programming over the clock bus (44) and data bus (46), input/output word extender circuits (104, 106), a high voltage protection circuit (420) including a transistor (600) and a data bus integrity checker (630).

Abstract: A circuit for reversing a voltage polarity on a first electrode and a second electrode may comprise a first inductor connected between the first electrode and a negative terminal of an external power supply. The positive terminal of the power supply is connected to the second electrode. A diode and a first capacitor are connected in series across the first and second electrodes so that the cathode of the diode is connected to the first electrode. A second capacitor and a switching device are also connected in series across the first and second electrodes. A second inductor is connected between the switching device and the anode of the diode.

Abstract: A plurality of battery/voltage polarity switching circuits are constrained to operate in switching synchronism by a timing circuit associated with each polarity switching circuit that are interrelated to one another such that only the fastest response timing circuit is operative to supply a common synchronizing signal to all the polarity switching circuits.

Abstract: A power plant system architecture includes a plurality of battery polarity switching circuits for providing uninterruptible power/voltage to a plurality of loads, each of which is powered by low frequency AC, and which is also powered by a DC voltage. DC voltage is substituted for the AC voltage applied to the load should the voltage polarity processing circuitry in the power plant fail.

Abstract: A floppy diskette drive assignment interchanging apparatus for interchanging the drive letter assignments in a computer system is disclosed. The floppy diskette drives have a drive data cable that includes a number of data lines. The interchanging apparatus comprises an interchange control logic and an assignment interchange logic. The interchange control logic generates an optional interchange control signal, the interchange control signal signifies the requirement for interchange when it is in a first logic state, and signifies the requirement of maintaining no interchange when it is in a second logic state. The assignment interchange logic has a set of inputs connected to each of the data lines among the drive cable data lines that require interchanging, and has a set of outputs for outputting the set of inputs with an output assignment of either a forward or reverse order determined by the active and inactive status of the interchange control signal.

Abstract: The first zero crossing of the power signal, after the detection of an opening/closing signal, initiates a series of predetermined, timed, steps which reduces or eliminates the overvoltage after opening/closing a circuit breaker on a high power line.

Abstract: A clamping circuit for protecting circuits operatively connected between a control circuit, a driving circuit, a power source, and an output circuit includes an inductive flyback circuit to add current to the output circuit through the driving circuit, and a reverse power protection circuit operatively connected between the inductive flyback circuit and the control circuit wherein the reverse power protection circuit opens the inductive flyback circuit and provides an electrical connection between the power source and the output circuit allowing current to flow through the output circuit when the power source is connected to the driving circuit incorrectly.

Abstract: A power supply circuit is set forth which overcomes the problems associated with incorrect battery insertion. The power supply circuit includes first and second battery terminals for electrical connection to the battery. The first and second battery terminals are connected to a first transistor switching circuit. The first transistor switching circuit is responsive to power from the battery to through-connect a negative polarity power signal therethrough irrespective of the polarity orientation of the battery. The first and second battery terminals are also connected to a second transistor switching circuit. The second switching circuit is responsive to power from the battery to through-connect a positive polarity power signal therethrough irrespective of polarity orientation of the battery. The negative and positive polarity power signals are available for connection to a load device, such as a hearing aid amplifier.

Abstract: Disclosed is a three-value power supply device, adapted for supplying developing bias voltages to a copying machine. The device comprises a positive high voltage source, a negative high voltage source, first and second high voltage transistors serially connected between the positive and negative high voltage sources, with an output terminal connected to the junction point between two transistors, and a timing controller for selectively turning on and off the two transistors.

Abstract: A downhole instrumentation system comprises one or more transducers coupled in a DC current circuit between the star point of an electrical submersible pump and the chassis. A sensing circuit including a DC power supply and an ammeter is arranged to monitor the current drawn. The system includes active electronic components which provide a sequence of signals that may include reference and measuring signals or multiplexed signals from the transducers.

Abstract: An electronic device offering protection against connection of a direct current power supply unit with reverse polarity includes a branch disposed between two potential lines and including a reverse biased diode and a first component sensitive to a flow of current. A first switch is disposed on the downstream side of this branch, on one of the potential lines. A control circuit has two terminals receiving a control signal and, connected in series between those terminals, a second switch and a second component sensitive to a flow of current. The first switch, normally open, is closed by the second sensitive element if the latter detects a flow of current. The second switch, normally closed, is opened by the first sensitive component if the latter detects a flow of current.

Abstract: A device for protecting battery-powered semiconductor devices and the like against a reverse battery condition. During normal operation a charge pump charges the gate of a power MOSFET, turning the MOSFET on and providing a low-resistance power supply path from the battery to the load. If the battery is reversed, a depletion mode device shorts the gate and source of the MOSFET, turning it off and disconnecting the load from the battery.

Abstract: A switch unit receive an AC signal and includes first and second push-button switches and at least one rectifying diode. Each of the first and second push-button switches is a 2-stage switch or a 3-stage switch. The first and second push-button switches and the at least one rectifying diode are configured such that the switch unit selectively generates any one of a non-signal, a positive half-wave rectified signal, a negative half-wave rectified signal and a full wave alternating signal to first and second outputs. The first and second outputs of the switch units are transmitted to an output unit by way of two transmission wires, respectively. The output unit discriminates the switching state of the first and second push-button switches based on the signal received from the switch unit via the two transmission wires.

Abstract: An environmentally tolerant personal identification, access control and monitoring system including a dual contact limb-worn identification (ID) code-producing unit and a multiple-physical contact arrayed ID code reader are described. Momentary physical contact between the unit's dual contacts, in any position and orientation, and the reader's arrayed multiple contacts is detected by sequentially energizing contact pairs of the array until a characteristic low-impedance is sensed and then the indicated contact pair is reverse-energized to read the ID code from the ID unit. Preferably, the contact array geometry is of closely spaced, nickel-plated, planar, hexagonally shaped conductors that are group-encoded and -energized to minimize the input/output port requirements of a microprocessor and associated drive/sense electronics that accomplish the scanning of the array and the reading of the ID unit.

Abstract: A programmable output connector of an implantable cardioverter-defibrillator (ICD), or similar implantable medical device, allows each of a multiplicity of output terminals to be selectively connected to either a positive or a negative output bus of the ICD. The positive and negative output buses of the ICD, in turn, are switched to an output capacitor, or equivalent output circuit, of the ICD. An electrical charge stored on the output capacitor, or otherwise generated by the output circuit, is presented to the multiplicity of output terminals in accordance with a programmed polarity. The programmed polarity causes a selected one or group of the multiplicity of output terminals to be connected to the positive output bus, and a selected other or group of the multiplicity of output terminals to be connected to the negative output bus. Respective electrodes designed for contacting cardiac tissue may then be electrically connected to each one of the multiplicity of output terminals.

Abstract: A circuit for protecting direct current (DC) powered devices from excessive supply voltage and reverse polarity supply voltage comprises supply voltage coupling circuitry that operably couples a DC powered device to a supply voltage. The circuit also includes a first field effect transistor (FET) having an intrinsic diode operably coupled to the supply voltage coupling circuitry. Further, the circuit includes first current blocking circuitry operably coupled to the first FET for blocking current flow through the intrinsic diode. Still further, the circuit comprises gate supply circuitry operably coupled to the first FET and the supply voltage coupling circuitry to supply gate voltage to the first FET when the supply voltage is less than a predetermined value.

Abstract: A switched receptacle includes a latching relay selectively providing power to an outlet receptacle. A drive circuit for the latching relay provides indirect feedback to a logic controller which follows or tracks each relay operation to ensure that the relay is in the commanded mode.

Abstract: A transmission device is disclosed wherein a plurality of control units each having a transmitting/receiving block connected to one another through a positive signal line and a negative signal line, and bidirectional signal transmission is carried out with a predetermined polarity among the control units. The signal lines of the transmission device are connected to a power superposing source for applying a predetermined DC voltage to the signal lines and each of the control units include a signal switch connected to the transmitting/receiving block for inverting and switching a transmission signal sent or received by the transmitting/receiving block, and a polarity judging device adapted to supply a homopolar signal when the potential of the positive signal line is higher than the potential of the negative signal line, and adapted to supply a heteropolar signal when the potential of the positive signal line is lower than the potential of the negative signal line.

Abstract: A switch unit receive an AC signal and includes first and second push-button switches and at least one rectifying diode. Each of the first and second push-button switches is a 2-stage switch or a 3-stage switch. The first and second push-button switches and the at least one rectifying diode are configured such that the switch unit selectively generates any one of a non-signal, a positive half-wave rectified signal, a negative half-wave rectified signal and a full wave alternating signal to each of first and second outputs. The first and second outputs of the switch units are transmitted to an output unit by way of two transmission wires, respectively. The output unit discriminates the switching state of the first and second push-button switches based on the signal received from the switch unit via the two transmission wires.

Abstract: A reversing switch and more particularly a diaphragm operated electrical polarity reversing switch which has general utility but in the application the reversing switch is disclosed for use in combination with a vehicle mounted spray device including a discharge nozzle which may be used for applying chemicals, liquid fertilizers and other liquids such as when applying such materials alongside of roadways to effectively apply liquid throughout the width of the road right-of-way in which spray nozzles are mounted adjustably on a pivotal arm-type support assembly at the right front of a vehicle and a control arrangement is oriented in the cab of the vehicle to enable the vehicle operator to control the spray apparatus.

Abstract: A soft start tool handle trigger switch circuit (10) applies voltage from an AC source (12) to a portable tool electric motor (10). A current limiter (30) is connected in series between the AC source (12) and motor (14). A first sub-circuit (32) is connected in parallel with the motor (14) and includes actuator circuitry (34) tripping an actuator solenoid (36). A second sub-circuit (40) is connected in parallel with the current limiter (30) and has a pair of contacts (44, 46) actuated from an open condition to a closed condition upon movement of an actuator plunger (38). An NTC thermistor (48) is connected in series with the actuator circuitry and is physically proximate and heated by heat from the current limiter (30) to reduce the resistance of the NTC thermistor (48) and supply increased current to the actuator circuit (34) for earlier closing of the bypass sub-circuit (40), to stop the current-induced heating of the current limiter (30).

Abstract: Amplification or generation of very low (and variable) frequency, low voltage, high current bipolar signals useful in electrical borehole telemetry systems is achieved using a duty cycle control device for causing the alternate direct application of a positive voltage and a negative voltage to an integrator. A commutated clamp is connected to the input of the integrator for switchably connecting the integrator directly into a current loop with the load, connected to the output of the integrator, when neither voltage is being applied to the input of the integrator.

Abstract: The polarizing potential transfer switch system takes advantage of an existing loss-of-potential (LOP) circuit (32) in a power transmission line protective system to differentiate between a trip signal produced by the distance elements in a protective relay (22) due to the operation of the transfer switch and a true fault condition. This is accomplished by a logic circuit (40) which includes a first timer (58) which permits the operator of the transfer switch (10) five seconds to complete the potential transfer operation between two buses (14 and 16) and a second timer (68) which gives the LOP circuit (32) a selected number of cycles in which to block a trip signal produced by the distance elements in the relay (22).

Abstract: A polarity switch changes the direction of DC to various loads in response to a sensed loss of AC and nonessential loads are shed in response to a sensed change in DC polarity at the various loads.

Abstract: An electronic detection circuit such as a proximity switch or flow detector uses a presence detector with complementary outputs and one or more electronic switches to provide either normally-open or normally-closed operation based on the polarity of the supply connections to the device. In one embodiment, two electronic switches are provided, each operating in response to one of the complementary outputs, with each switch connected to provide current flow in a mutually opposite direction between the supply connections upon activation. In another embodiment, a single electronic switch is provided, and is connected through a diode matrix to the complementary outputs.

Abstract: An electrical circuit supplying a load from a voltage source includes a switching device and a diode, and is to be protected from recovery current caused by momentary reversal of the diode current during the operation of the switching device. The electrical circuit further includes a transformer having an excitation winding sensing the reverse recovery current through the diode immediately after operation of the switching device, and a sink winding inductively coupled to the excitation winding for inducing in the sink winding a current proportional to the current in the excitation winding. A unidirectional conducting device directs the current induced in the sink winding to the diode to cause reverse recovery of the diode.

Abstract: An alternatable constant current circuit is provided which supplies positive and negative polarities of rectangular wave current to an inductive load such as in an exciting circuit of an electromagnetic flowmeter and in a slanted magnetic field system of a nuclear magnetic resonance imaging device at a high current inversion speed and a low power loss, wherein the capacitance of an output capacitor in a switching power source circuit is lowered, the regenerative output voltage of the output capacitor is applied to the inductive load during the current inversion period therein via a polarity inversion circuit, further the load current is controlled by a current control circuit at a predetermined value and the output voltage of the switching power source circuit is also controlled so as to maintain the collector-emitter voltage Vce of a current control transistor in the current control circuit constant, whereby an oscillation is generated in the circuit including the inductive load and the output capacitor duri

Abstract: The resolution of two asynchronous three-phase power sources such that an optimal phase to phase matchup may be made between them. This is achieved with a logic system that receives a data point at the zero-voltage crossings of the three waveforms from each source. The data points create distinct "states" of the three-phase waveform for each power source. There are six data points for each power source per cycle. The states of the load and source, along with information pertaining to the connection configuration of the present source of power to the load, are used to determine the optimum configuration for connecting an alternate or new source to the load based on information obtained from a lookup table.

Abstract: A transformer isolated circuit for driving a semiconductor power switch includes a transformer which is driven with a high frequency Pulse Width Modulated (PWM) signal in such a way that the constantly present PWM carrier supplies the power needed for high gate current pulses, while different duty cycles determine the "on" or "off" state of the power device under control. Transformer saturation is prevented by sensing primary current and returning it to zero once per PWM cycle. Because of the high PWM carrier frequency used, the average transformer power is low, yet the secondary side is able to deliver high pulse currents for fast "on-off" switching of the gate of even the largest N- or P-channel device, without need for auxiliary power supplies. Also included are provisions for extremely fast output current limiting, for use where short circuit protection is necessary. Discussion of a monolithic implementation is included.

Abstract: Voltage sensing circuitry monitors the signal input lines of a standard RS232 serial data interface. The voltage levels at the inputs of the interface are compared to known voltages to determine if the correct interconnections have been made between the interfaced devices. If the interconnections are determined to be incorrect, a switching circuit is enabled to correct the faulty connections, and serial data transmission is thereafter initiated.

Abstract: A battery pack mounting device for portable radio equipment having a built-in antenna. The device determines a position of a battery pack, which powers the equipment, inserted in a battery pack accommodating portion provided in the equipment. Various constants which determine the antenna characteristic of the equipment are controlled on the basis of the determined position of the battery pack, thereby maintaining the optimum antenna characteristic at all times. When the device is applied to a charging unit which charges a rechargeable battery, the opposite electrodes of the battery are electrically correctly connected to a pair of connecting terminals which are provided in the charging unit and connected to opposite poles of a charging circuit as the battery pack is inserted in a battery chamber defined in the charging unit. Even when the battery pack is placed in the battery chamber upside down, the opposite electrodes of the battery are accurately connected to the connecting terminals of the charging unit.

Abstract: A polarity inverting circuit includes first and second output voltage transmission circuits, first and second connection circuits, first and second polarity switching time changing circuits, and a controller. The first output voltage transmission circuit is connected to a first signal line to linearly change an output voltage from a first potential to a second potential. The second output voltage transmission circuit is connected to a second signal line to linearly change an output voltage from the second potential to the first potential when an output voltage from the first output voltage transmission circuit reaches the second potential. The first connection circuit connects the first signal line to a second potential source when the output from the first output voltage transmission circuit reaches the second potential. The second connection circuit disconnects the second signal from the second potential source when the first connection circuit is connected to the second potential source.

Abstract: Amplification or generation of very low (and variable) frequency, low voltage, high current bipolar signals useful in electrical borehole telemetry systems is achieved using a duty cycle control device for causing the alternate direct application of a positive voltage and a negative voltage to an integrator. A commutated clamp is connected to the input of the integrator for switchably connecting the integrator directly into a current loop with the load, connected to the output of the integrator, when neither voltage is being applied to the input of the integrator.

Abstract: An apparatus which is inserted in a signal transmission path between a network communications cable and a sending and receiving circuit. The apparatus enables switching of the connection polarity of the communications cable. This apparatus has an idle status detection section, a judgment section which responds to an idle status detection of the idle status detection section and judges the polarity of the communications cable on the basis of a signal level of the communications cable, and a polarity switching section which switches the polarity of the signal send and receive in accordance with a polarity indicated by polarity judgment signals output from the judgment portion. The use of this apparatus eliminates the necessity to recognize the polarity when connection work is performed, and simplifies the connection work itself.

Abstract: A detachable operating unit for connection with a main unit comprises at least two power supply units for applying operating voltages to the detachable operating unit, the power supply units generating two different voltages, respectively; at least two power supply terminals for engaging the detachable operating unit and the main unit to receive two different voltages applied to the power supply units, respectively; a ground terminal for engaging the detachable operating unit and the main unit; a protective circuit for applying a reverse voltage in repsonse to a differential voltage between voltages of the power supply units, the protective circuit being disposed between one of power supply units which generates the operating voltage lower than that of the other power supply unit, and the ground terminal.

Abstract: An electric heating appliance which is provided with a connecting terminal selecting circuit for the purpose of generating heat in an electric heater in a negative cycle of a commercial AC power source no matter which pole of a plug is connected to a grounding electrode of the power source when the plug is inserted into a plug socket of the power source, the connecting terminal selecting circuit consisting of a delay switch circuit adapted to insulate a heater circuit from the power source for a predetermined period of time when a power source switch is turned on, a heater potential detecting circuit adapted to detect the grounding electrode of the power source, and a change-over switch circuit adapted to connect the anode of an electric power controlling rectifying element for controlling the electric heater to the grounding electrode of the AC power source in accordance with an output signal from the heater potential detecting circuit.

Abstract: The present invention relate to an atomic scale electronic switch wherein the position of one or more atoms (12, 20) or molecules is varied to control the state of the switch. Terminals (10, 11, 21-23) may be tips of scanning tunneling microscopes or STMs. A change in position of the switch will result in a change in conductance between the spaced apart terminals. Voltage or current pulses cause the switching element (12) to change positions.

Abstract: A dynamic isolation circuit belonging to a monolithic integrated circuit comprising lateral transistors and vertical transistors. The lateral transistors are isolated by an isolating region connected to an isolating potential (V.sub.iso), these lateral transistors being connected up to voltages of a first polarity relative to a reference voltage (GND), the power terminal connected up to the rear face normally being at a potential (V.sub.out) of the first polarity relative to the reference voltage.

Abstract: Synchronization pulses for an internal combustion engine are generated by identifying the second of two consecutive pulses of the same polarity in a pulse train of positive going and negative going pulses. An evaluation pulse sequence is generated which switches from a low level to a high level in response to a positive going pulse and from the high level to a low level in response to a negative going pulse. A synchronization pulse is generated in response to a differentiated pulse derived from the pulse train when the level of the evaluation pulse sequence indicates that a switching pulse of said same polarity as that of the differentiated pulse has just occurred.

Abstract: A solid state, static power supply control mechanism for coordinated transfer of a load from a preferred source of AC power to an alternate source of AC power should the level of power transmitted from the preferred source fall below a set, adjustable level and thereafter, upon re-establishment of the proper level of operating power of the preferred source, re-transfer of the load from the alternate source to the preferred source. A unique method of current interlock prevents the alternate power source from connecting to the load until the current from the preferred source is absolutely interrupted, with the same criteria required for re-transfer from the alternate to the preferred source of power. This mechanism and associated switching technique insures supply of power to the load regardless of the preferred power source failure mode and regardless of the phase relation of the preferred and alternate sources of power.

Abstract: An integrated circuit self-protected against a reversal of its supply battery polarity comprises a first DMOS power transistor connected with its source electrode side to an electric load to be driven toward ground, and a second, protective DMOS transistor which is connected with its source electrode side to a positive pole of the battery and with its drain electrode side to the drain electrode of the first transistor. The first and second transistors have in common the drain region formed on a single pod in the semiconductor substrate.

Abstract: A protective device for an electric control circuit having first and second input buses to be applied with a source voltage of low level from a commercially available source of electricity and an electrical load of low rating voltage connected between the input buses. The protective device is in the form of a switchover relay disposed between the input buses and the electrical load for maintaining the electrical load in connection to the input buses when applied with the source voltage of low level and for disconnecting the elecrical load from the input buses when applied with a source of high level from the source of electricity. The operating voltage of the switchover relay is determined to be higher than a maximum allowable voltage of the electrical load and to be lower than a lower limit value of the source voltage of high level.

Abstract: The subject invention provides a coil driver circuit having protection against a reverse-polarity battery connection and is suitable for use in such control modules. The driver circuit controllably actuates N coils in response to control signals supplied by the control module. The driver circuit includes N control switches, each coupled in series between a first terminal of an associated one of the coils and a first common junction. The first common junction is normally connected to a positive reference terminal of the electrical power source. The control switches are adapted to controllably connect the coil first terminals to the power source positive reference terminal in response to externally supplied control signal. The coils have second terminals connected at a second common junction, and the second common junction is normally connected to a negative reference terminal of said power source.