Abstract: An intrinsically safe battery pack arrangement for electrically powering electrical devices is disclosed. The power pack has a device for electronically determining a short in a cable or device and switching off the voltage to the power pack. The electronic device includes a transisterized circuit for sensing and controlling current through the cable. When the current exceeds a predetermined maximum, the circuit limits the current in the cable to a maximum value. The circuit is latched in the off position when the short is present for an extended time and the circuit may be reset after the short is removed and the problem corrected. This form of circuitry in power packs for use with mining equipment such as lamps, provides a unit which will not cause hazardous sparks when shorted thereby constituting an intrinsically safe device for use in mines.

Abstract: A control system for regulating a system parameter includes three sensing elements to independently sense a single system parameter and provide respective feedback signals. Three substantially identical controllers are responsive to these feedback signals with the controllers each having a bridge network of three resistors and being connected to a common resistor. In response to the feedback signals and signals representative of the imbalance in the bridge networks, the controllers act to cause bridge balance by collectively supplying current to the common resistor to effect a balance and to thus control the system parameter in accordance with the middle valued of the three feedback signals.

Abstract: A safe operating area circuit in combination with a current sensing circuit is coupled to an input voltage line and has a control line input in which the combination provides a current limited output on an output voltage line in response thereto. Break-points may be selectably established in the current limit curve for the output switching device by means coupling the input and output voltage lines.

Abstract: The invention is a dual input voltage regulator that has four active parts: a transistor, a resistor, a zener diode and a capacitor. It has one input for main power and one input for turn on power. The dual input allows lower main input voltage and allows the regulator to be synchronized with load.

Abstract: An output circuit to drive a current into a load. Collector voltage of a current controlling transistor is automatically adjusted to maintain h.sub.FE of the transistor constant, whereby saturation of the transistor and excessive power consumption are avoided. A brushless motor using the output circuit. Current detectors detect emitter current and base current of output transistors and h.sub.FE of the transistors are kept constant, whereby excessive torque loss and harmful vibration are avoided. A limiter limits excessive torque control to prevent power transistor saturation. A switching mode power supply adjusts the collector voltage of the transistor in a feedback loop to keep h.sub.FE constant.

Abstract: Field effect transistors are used in a series current limiter circuit. The field effect transistors are depletion type transistors and are interconnected in a manner to decrease conduction when an overvoltage or overcurrent condition is sensed. Biasing resistors are used to maintain the transistors in a non-conductive state until the overvoltage or overcurrent condition is removed.

Abstract: This invention concerns a regulated-current source and a controlled-voltage generator comprising an injector (Ir) kept at a constant potential (U.sub.1) by a regulation loop (D.sub.1, C.sub.1) which by means of a unit (C.G.) controls the intensity (i) of the current flowing in a load (R).

Abstract: A three terminal integrated low-resistant series switch circuit which buffers load electronics from extreme input voltage conditions. The circuit comprises a series pass transistor the conductivity of which is controlled by control circuitry in cooperation with feedback control. In response to the input exceeding a predetermined operating potential the series pass transistor is driven toward saturation and is maintained in this state by feedback whereby only that load current required by the load electronics is supplied for increased efficiency. The control circuitry is responsive to the signal at the input thereof exceeding a predetermined level for rendering the series pass transistor nonconducting to protect the load electronics from extreme voltage excursions. A feature of the circuit is that the epitaxial layer within which the control circuit is formed is operated at a lower voltage than that of the substrate.

Abstract: Direct current inrush upon connection of a capacitive load to a d.c. voltage is limited through an intermediary circuit. Within such circuit the inrush current is sensed by a series resistance and such sensing is utilized via a feedback loop, to control a series current regulating transistor to be cyclically conducting or non-conducting of a first direct current path. A second direct current path through freewheeling diodes flows current to the load only when such series current regulating transistor is non-conducting of such first path current. After fully charging the capacitive load, howsoever slowly as desired, the first current path conducts with low power dissipation while the second current path is non-conducting. The circuit is further controlled to be correctly operative for control of inrush current during the turn-on, or disruption of, fundamental power to such circuit.

Abstract: An overcurrent protection system adaptable for use with power controllers the single or multi-phase ac, or dc types includes a load current sensing element in combination with an overcurrent sensing/inverse time delay circuit, a power switch and a crowbar circuit. The system also includes a drive circuit, a drive circuit input current sensor, a trip signal detector and a logic circuit. The overcurrent protection system, according to the present invention, uses the drive circuit to power the overcurrent sensing/inverse time delay circuit, to drive the power switch, and to provide a coupling path for an overcurrent fault signal across electrical isolation interface(s) thereof to the logic circuit. Thus, the need for a separate isolated power supply for powering the overcurrent sensing/inverse time delay circuit and the need for separate optical and/or electromagnetic isolation interfaces for coupling of the overcurrent fault signal are eliminated.

Abstract: An induction heat cooking apparatus includes an inverter which generates ultrasonic frequency energy for heating a magnetic load by induction, and a small load detection circuit. The detection circuit includes a comparator which compares the input and output parameters of the inverter and latches a bistable device when the input power is smaller than the output parameter. The bistable device shuts down the inverter to prevent inadvertently placed small utensil objects from being excessively heated.

Abstract: A regulated substrate bias voltage generating system for maintaining a minimum data retaining current through an associated MOS memory. The negative substrate bias voltage is generated by a charge pump operating under the control of a two-phased output oscillator, the operation of which is enabled and disabled by the output signals from a MOS memory over-current sensor, a MOS memory under-current sensor, and a bias voltage level sensor.

Abstract: A solid state current sensing circuit which is useful in a power supply has bipolar as well as CMOS transistors. The bipolar transistors serve as output transistors and have lateral collectors as well as substrate collectors. The lateral collectors of the bipolar transistors are used to sense a portion of the current carried by the substrate collectors. The lateral collectors are connected to a current mirror which provides an output indication of when the output current exceeds a predetermined amount. The entire circuit can be integrated on a single chip.

Abstract: A transistorized circuit is used for controlling the flow of current through a high voltage source, such as a battery. The high voltage source must be capable of being tapped at voltages less than the critical voltage of the transistors in the circuit, that is, that voltage at the maximum current through the transistor, above which the breakdown characteristics or maximum power dissipation ability of the transistor is exceeded. A plurality of transistor arrays are connected in series with each other, and each array is connected to a tap on the voltage source. Each array includes parallel connected transistors in sufficient quantity to achieve the desired current flow. The current through each array is made equal by control circuits so that no current flows through the tapped connection to the voltage source. The transistorized circuit may be used to control both the charging and the discharging rate of current through a high voltage battery.

Abstract: A -DC to +DC voltage converter having one input and one output terminal connected to ground and regulator circuitry responsive to a control voltage for regulating the magnitude of output current delivered to a load impedance connected across the output terminals. Apparatus producing the control voltage comprises a passive resistive bridge circuit having one pair of nodes connected between the other input and other output terminals and a current sensing resistor in one arm of the bridge so as to pass load current to the other output terminal, a difference voltage that is the control voltage being developed between the second pair of nodes of the bridge. In one embodiment, the bridge comprises a potentiometer having a moveable contact connected to the other input terminal, and first and second pairs of series connected resistors connected between opposite sides of the potentiometer and opposite sides of the current sensing resistor.

Abstract: A series pass voltage regulator compares the output voltage with a reference voltage and adjusts the base bias of a PNP series pass transistor coupled between an unregulated voltage source and a load to maintain the output voltage at a predetermined constant value. A current sensing resistor senses the base current of the PNP series pass transistor and limits the base current to a predetermined value indicative of a maximum allowable load current.

Abstract: A solid state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by mechanical toggle switch for close simulation of magnetic circuit breaker operation in three phase or other multiphase systems. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit except the static power switch branch. The control switch is located between two of the supply voltage phases and the power supply for the control circuitry. The correct zero crossover of one phase is utilized to produce turn-on at zero degrees of that one phase while the other two phases are respectively at minus 120.degree. and plus 120.degree. without any significant impairment of overall circuit breaker performance. An overcurrent protection system is included that uses optical isolators with reduced sensing voltages developed directly from terminals of the power switch elements.

Abstract: A solid-state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by a mechanical toggle control switch for close simulation of magnetic circuit breaker operation. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit, except the static power switch branch, between the source and the load, to provide a high degree of fail-safe protection for the apparatus. The power continuity feature includes means for zero crossover synchronization both upon power-up and power-down conditions. A circuit lockout feature is used so that on power-up or turn-on, operation is delayed until the occurrence of an internal power-ready condition. On power-down or turn-off, there is means for circuit retention subsequent to switch opening and internal power removal in order to accomplish load turn-off at a desired zero crossover point of the load power through the power switch.