Abstract: A DC-to-DC voltage-increasing power source suitable for use in an audio device mounted on an automobile or a portable type audio device includes a DC power source, a drive pulse generation circuit for generating drive pulses which are in 180 degree phase relationship, a switching circuit of a push-pull connection supplied with operating voltage from the DC power source and driven between an on-state and an off-state in response to the drive pulses, a charge and discharge circuit including capacitors charged by being connected in parallel to the DC power source and discharging a sum voltage by being connected in series to the DC power source and an output takeout circuit for taking out this sum voltage as a voltage-increasing DC output. The switching circuit is constructed of voltage-controlled type elements whose on-state is changed in response to the level of an on-pulse in the drive pulses and the drive pulse generation circuit includes a pulse level changing circuit for changing the level of the on-pulse.

Abstract: Disclosed is a novel switching circuit directed to use for limiting surge into lamp, comprising a diode circuit wherein two sets of diodes are connected in reverse-parallel; a resistive element connected in series with a lamp to limit the switch-on surge thereinto; a bidirectionally conductive element having a main current path connected in seried with an ac source through said resistive element, diode circuit and lamp; and a timing circuit having a time constant, said timing circuit triggering said bidirectionally conductive element with the voltage across said diode circuit to short-circuit said resistive element after a lapse of said time constant from switch-on.

Abstract: A highly accurate current-limiting circuit prevents an output current (I.sub.OUT) flowing through an output line (L.sub.OUT) from exceeding a specified value (I.sub.LIM) of an input current (I.sub.IN) flowing through an input line (L.sub.IN). The circuit contains a first channel device (10) controlled by a first reference voltage (V.sub.REF1), a current source (12) that supplies a reference current (I.sub.REF), a second channel device (14) controlled by a second reference voltage (V.sub.REF2), a current bypass device (16), and a bypass control system (18). The current gain below the specified value of the input current is close to one. By suitably choosing certain of the circuit parameters, the circuit operates in a substantially temperature-independent manner.

Abstract: A lamp driver circuit for supplying and controlling power to a lamp from a power supply subject to voltage variations. A semiconductor switch is disposed in series with the lamp and a current sensing resistor. A capacitor integrates the lamp current during ON time of the switch and power supply voltage during OFF time. A voltage comparator with hysteresis responds to the capacitor voltage to control the conductive state of the switch. Above a nominal supply voltage, the driver circuit begins to pulse width modulate the power supplied to the lamp with a duty cycle inversely proportional to the square of the supply voltage to maintain constant power to the lamp. As the supply voltage rises above a second predetermined level, the driver circuit ceases to supply power.

Abstract: A power relay for a switching control device of a microwave oven, designed to prolong the life of the power relay by alternately carrying out the drive of the power relay used for controlling the power in a microwave oven at the positive (+) cycle and the negative (-) cycle of the alternating current input voltage, respectively. The output signal of the 50 Hz/60 Hz clock generator for generating the clock signal corresponds to the frequency of the alternating current input voltage and is combined with the output signal of the power relay ON/OFF generator. The power relay ON/OFF control part is composed so as to alternately realize the ON-point and the OFF-point of power relay at the positive cycle and the negative cycle of the alternating current input voltage, respectively, so that no potential difference takespace in one direction between contact of the power relay, and the life is thereby prolonged.

Abstract: A control device for energization of a load employs a bidirection triggerable solid state switching device connected in series with an alternating current power source and the load. In order to prevent the passage of excessive, potentially destructive currents through the switch if the load is shorted out, the microprocessor which controls the energization of the switch senses the time required for the voltage across the switch to attain a predetermined value. If the load is shorted the potential difference across the switch increases and attains the predetermined value a shorter time after zero-crossing of the alternating current. When this occurs more than a predetermined number of consecutive times, the generation of triggering pulses for the solid state switch is inhibited for a predetermined time. In the preferred embodiment the control device is a thermostat for controlling a temperature modifying load such as a furnace or air conditioner.

Abstract: A power controller having first and second power outlets, connections between one side of an A.C. line to one side of each outlet, a current sensing impedance connected between the other side of the A.C. line and the other side of the first power outlet, a triac connected between the other side of the A.C. line and the other side of the second power outlet, a first operational amplifier normally maintaining the triac in a non-conductive condition and a second operational amplifier to cause current to flow through the triac to the second power outlet after a selected time delay whenever an appliance such as a power tool that is coupled to the first power outlet draws a given amount of current through the sensing impedance.

Abstract: A method and apparatus are disclosed for detecting excessive current draw in an electrical load particularly of the type having an in-rush current when first energized. The electrical load is connectable to an energy source through a current sensing circuit and an actuatable switch. The current sensing circuit provides a load sense signal that varies in response to current draw by the load. A control signal is provided to actuate the switch. A coupling network temporarily couples the control signal to the load sense signal to offset the change in the load sense signal resulting from current in-rush. The load sense signal is compared against a reference signal. The comparator outputs a signal indicative of whether the load sense signal is greater or less than the reference signal. One signal from the comparator is indicative of excessive current draw.

Abstract: A following voltage/current regulator includes a field effect transistor (FET) (48) connected in series between an unregulated voltage source (44) and a load, such as a motor bridge circuit (50). The conduction of the FET is controlled by a control circuit (56) which measures the input voltage to the FET source, the output voltage from the FET drain and the current drawn by the load. Initially, when power is turned on, the inrush current to the load is limited until a predetermined voltage differential between the input and output voltages is achieved at steady state. Then, the voltage regulator maintains the predetermined voltage differential to provide a well regulated output voltage to the load despite fluctuations in supply voltage. This "following" action limits the heat disipation and protects the FET. Because the voltage regulator uses no inductors or transformers, there are no saturation problems and the circuit may be compactly packaged.

Abstract: Disclosed is a device for limiting the inrush current in a lamp, comprising a resistor means to limit the inrush current that may arise in a lamp, the resistor means being connected in series with the lamp and power source; a controlled rectifier (main controlled rectifier) having the main currrent path connected in parallel with the resistor means; another controlled rectifier (secondary controlled rectifier) having the main current path connected with the gate of the main controlled rectifier; and a delay circuit (e.g. RC-time constant circuit) having the output connected with the gate of the secondary controlled rectifier in such manner that the power source energizes the lamp through the resistor means over the time as predetermined by the time constant of the delay circuit.

Abstract: A regulating control circuit for a single-ended switching power supply includes means for controlling the switching duty cycle during start-up, normal operation and current limiting modes. Normal operation utilizes a duty cycle of less than about 50%, but low input voltage operation can occur for limited times at duty cycles up to 70%-80%. A time base generator defines the maximum permissible switch conduction time, as well as the switching rate. During start-up, input current is restricted to reduce dissipation within the control circuit, the start-up duty cycle also being maintained at a low value by extending the switch non-conduction time. In the current limiting mode, the duty cycle is reduced as a function of current demand to achieve constant current operation over a given range of output voltages, and to achieve current foldback below such range. In current foldback, the switch non-conduction period is extended to obtain unusually low duty cycles in near shorted output conditions.

Abstract: A compensation circuit includes a circuit for monitoring the current delivered to a load and for producing a switching signal whenever a current spike is detected. A control signal representative of the desired voltage across the load is produced. A power supply supplies voltage to the load in response to the control signal. The circuit for generating the control signal is responsive to the switching signal for adjusting the control signal such that when a current spike is detected the voltage delivered to the load is substantially instantaneously reduced.

Abstract: A circuit for protecting an AC/DC, DC/AC or DC/DC convertor power supply which is fed from a supply source which may contain spikes or transients, comprising links of relatively lower and higher resistance connected in parallel in the current supply path from the power supply, and a feed back signal generator producing a feed back signal which varies responsively to variations in the power supply and is utilized to change the effective resistance of the low resistance link and thereby limit the current applied to the convertor transformer.

Abstract: A supply circuit for an apparatus which is provided with a supply voltage which is low relative to the amplitude of a main voltage supplied from a main power supply network. The switching apparatus has a switching line arranged in the main power supply line, which is connected in series with a load, and in which the supply circuit is connected in parallel with a power-dissipating or resistance element connected in series with the load.

Abstract: The medical current limiting circuit is for use with medical electrodes and associated diagnostic and therapeutic apparatus. The device protects the apparatus and patient from current flow. The device has circuitry comprising a pair of external connectors, a pair of n-type field effect transistors connected in cascade, a resistor, a p-type field effect transistor, a capacitor to latch the p-FET in a non-conductive state upon its initial activation and a diode to prevent capacitor discharge to the current source.

Abstract: A high tension power supply for use in an x-ray tube drive circuit which uses a step-up transformer to raise an input line signal to the desired voltage level. A partially open bridge or other suitable means permits only half cycles, for example positive half cycles, of the transformer output to be applied to fire the x-ray tube. Saturation of the transformer core during unused half cycles, for example negative half cycles, is prevented by adding a compensating impedance in series with the circuit passing the unused half cycle to the transformer primary, the increased voltage drop across this impedance as current increases in response to the transformer approaching saturation reducing the voltage across the transformer so as to maintain the average voltage across the windings during both half cycles substantially equal. This achieves "constant phase" exposures without transformer saturation.

Abstract: A series voltage regulator having a regulating transistor (T.sub.1) arranged with its emitter-to-collector path in a series arm of the regulator, the base of which is controlled via a control transistor (T.sub.2) by a first differential amplifier (V) which compares a reference voltage (U.sub.REF) with a voltage proportional to the voltage (U.sub.2) of the regulator output. A differential circuit (V.sub.2) which compares the collector-to-emitter voltage of the regulating transistor (T.sub.1) with an auxiliary voltage (U.sub.3) is provided, the output of which is followed by a current limiting circuit (T.sub.3) which acts upon control transistor (T.sub.2). The auxiliary voltage (U.sub.3) is larger than the collector-to-emitter voltage of the regulating transistor (T.sub.1) which occurs at the beginning of the saturation state of the regulating transistor. The current limiting circuit (T.sub.3) limits the current delivered by the control transistor (T.sub.2) to the base of the regulating transistor (T.sub.

Abstract: A solid state switching circuit is provided with a first power sharing circuit which incorporates resistive power dissipation elements so that the required dissipated power is shared between a main power transistor and the power sharing circuit. A second power sharing circuit is connected in parallel with a portion of the first power sharing circuit and operates to provide additional resistive power dissipation under certain switch voltage conditions. The use of this second power sharing circuit permits an increase in the required trip time of the main switching transistor or improves the reliability of the power transistors in the main circuit and the first power sharing circuit by lowering transistor stress during transient conditions.

Abstract: There is disclosed a surge current-limiting circuit including a current-limiting means connected in series with a load; a controlled rectifier connected in parallel with the current-limiting means; a photocoupler; and a delay circuit having a time constant, connected through the photocoupler with the gate of the controlled rectifier.

Abstract: Electrical control apparatus including a power supply, a regulating element, a manually-operable control device which can be set to provide a preset output from the regulating element, and an automatic control circuit for modifying the operation of the control elements in the event of a power failure. The automatic control circuit is so arranged as to rapidly reduce the output to zero when the absolute supply voltage falls below a predetermined level, and to progressively raise the output to the preset level when the supply voltage is restored.

Abstract: An inrush current limited power supply includes a regulator with a capacitor coupled across its input terminals. If voltage to be regulated is suddenly applied by a switch to the input terminals of the regulator, an undesirably large current surge occurs as the capacitor charges. The magnitude of the current surge is limited by a surge limiting resistor coupled in series with the switch. This limits the surge current, but undesirably causes power dissipation in the resistor during normal operation. The channel of a FET is connected across the resistor. The FET has a conductivity which is low when the gate-to-source voltage is low, for preventing large inrush current immediately after turn-on. A control voltage generator generates a control voltage by rectifying an alternating voltage, and it is coupled to the gate and source of the FET. In one embodiment, the control voltage generator is referenced to an input terminal of the regulator. In another embodiment it is referenced to output terminal.

Abstract: A power switching means for connecting a power source to a digital data processing system. The switching means includes a power switch for connecting the power source to the system and two control switches. A first control switch determines whether system power is to be turned on or off and is responsive to a turn-on selection signal to provide an initial turn-on signal to the power switch if a power turn-on is to be performed. The second control switch is responsive to a power turn-on/turn-off initialization signal to initiate and control the turn-on and turn-off operations. The second control switch is responsive to the initialization signals at power turn-on to enable the first control switch to be responsive to a power-on selection signal to provide the initial turn-on signal to the power switch.

Abstract: In a switched mode power supply during start-up, an increasing charge on a soft-start capacitor controls a pulse width modulator for increasing the length of drive pulses provided to a pair of switching transistors until a reference voltage level is reached, after which stable power supply operation ensues. Detection circuitry senses a low power supply output voltage such as arising from input line interruptions and rapidly discharges the soft-start capacitor and prevents the recurrence of the soft-start mode of operation before the soft-start capacitor is fully discharged to prevent overloading of power supply output semiconductor devices upon the resumption of normal input voltage to the power supply.

Abstract: An MOS current limit circuit which provides current limiting protection is provided. A driver transistor of a conventional output stage is coupled to a current limiting transistor which is one transistor of a current mirror. The current limiting transistor of the current mirror has the V.sub.GS thereof accurately biased to insure a precise current limit value. When the current limiting transistor is not performing a current limiting function, the current limiting transistor is made conductive and further provides high voltage protection to the driver transistor when the driver transistor is nonconductive.

Abstract: The present invention provides a device for eliminating inrush-current, comprising connecting a power switch, pair of diode in reverse parallel, a resistance, a rectifier, a time constant circuit and a thyristor in a manner such that an ac current is supplied to a load through the resistance for a period, determined by the time constant circuit, after switching-on of the power switch, and that the rated current is supplied to the load after lapse of the period by allowing the thyristor both to conduct and to short the resistance.

Abstract: An AC power line transient suppression circuit comprises a bi-directional series breakdown element in combination with a series inductor and a shunt capacitor.

Abstract: A pair of PNPN thyristors are used to provide a solid state fuze for circuit protection. One of the pair of thyristors is self-biased on and provides normal current flow. The other thyristor turns the first thyristor off during a surge condition. A current sensing resistor is placed in series with the first thyristor to provide bias to the second transistor. The circuit will automatically reset itself when the surge condition is no longer present.

Abstract: A light bulb protection arrangement including a lamp, a socket, and a junction socket having a base portion and a socket portion so as to attach the light bulb to the socket. The junction socket includes a connecting terminal, a first terminal to be connected to the central electrode of the socket, a second terminal to be connected to the central electrode of the light bulb, and a negative temperature coefficient thermistor connected between the first terminal and the second terminal.

Abstract: A voltage driving circuit for a load requiring foldback current limiting characteristics, current limiting means and current latching means. The current latching means monitors the load current until a predetermined limit is reached, then latches the load current at a predetermined level lower than the predetermined limit until a logic signal is applied to the voltage driving circuit to turn off the load current. Such reduction in the current magnitude of the output current provides lower power dissipation in the load, a faster load turnoff time as a result of less energy stored in the load, and a more precise control of a variable duty cycle output.

Abstract: A power supply system for feeding low cold resistance incandescent lamps from a diode-rectified alternating current generator where the system does not have a battery or other voltage source for energizing the lamps. A control circuit is connected between the generator and lamps that includes a resistor that can be bypassed by the closure of relay contacts. The control circuit energizes the lamps such that generator voltage does not collapse when the relay contacts close. The resistor can have a negative temperature coefficient of resistance.

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 inrush current limiter includes at least a two-terminal circuit in series with a power load having a high gain high current Darlington transistor, a driver transistor for the high gain high current Darlington transistor, a current sensing resistor, a base-drive resistor, and a diode bridge interfaced for providing a peak-current-limiting function by proportional adjustment of the voltage to the power load as a function of current.

Abstract: An energization circuit for a microwave oven employs a PTC thermistor to eliminate high transient current surges resulting from energization and deenergization of induction elements therein to provide circuit protection both during oven start and operation. The energization circuit comprises first and second parallel circuit portions for energizing a transformer used to energize a magnetron that produces microwave energy, the first circuit portion including a normally open start switch and a current limiting PTC thermistor coupled in series relation and the second circuit portion including a relay operated switch, a relay for operating the relay operated switch, and a relay circuit portion connected to the first circuit portion between the start switch and PTC thermistor for energizing the relay upon closure of the start switch and then through the PTC thermistor upon opening of the start switch.

Abstract: A circuit for suppressing surge or transient currents between a DC power supply and a capacitive load includes a suppression impedance of relatively high impedance connected in series with the load between the DC supply and load, a transistorized control circuit for sensing the voltage across the load, and producing a firing signal when the level of voltage exceeds a predetermined level, and an SCR having its main current path connected in parallel with the suppression impedance, and its gate electrode receptive of the firing signal for turning on the SCR to by-pass the suppression impedance subsequent to application of power to the load.