Abstract: A phase control circuit according to the present invention is configured for connection between and AC source and an AC load. The AC source supplies an AC drive signal having a plurality of sequential positive and negative half cycles. The phase control circuit comprises first and second power switches coupled between the AC source and the AC load. The first power switch conducts current of the AC drive signal after a first phase delay during the positive half cycles. The second power switch conducts current of the AC drive signal after a second phase delay during the negative half cycles. A feedback balance circuit is coupled between the AC load and the first and second power switches. The feedback balance circuit determines a DC current component in the AC load and generates a phase delay correction signal as a function of the DC current component.

Abstract: A compact photosensor circuit provides automatic intensity range control for machine vision systems. The circuit may be implemented with standard CMOS integrated circuit technology to provide high sensitivity, fully static operation, and automatic exposure control with no moving parts. For each pixel of an imaging array, a photodetector provides an input photocurrent to a corresponding photosensor circuit. The photodetector is connected to provide an output voltage and an input to the gates of a pair of series-connected FETs that act as an attenuator. The attenuator is connected to a biasing source that provides a floor bias voltage. An output of the attenuator is connected to the gate of a third FET connected to the input photocurrent. The output voltage responds as a function of the light intensity at the photodetector while the bias voltage determines the range of light intensity for normal operation of the photosensor circuit.

Abstract: Synchronous switching inverter and regulator suppress rf emissions, and FET push-pull switching for the inverter provides high efficiency power transfer by sinusoidal transformer operation. Feedback control for both pass transistors switching and duty cycles insures overall synchronous behavior.

Abstract: The invention pertains to a switchmode DC-to-AC inverter, and particularly to a self-symmetrized and self-oscillating half-bridge inverter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially for high intensity discharge lamps, including power control, frequency modulation and high voltage ignition apparatus.

Abstract: A switching power source device includes a rectifying smoothing circuit made up of a full-wave rectifier 2 and a small-capacity capacitor 3, a resonance frequency controlled type resonance converter circuit 4 having a controlled resonance frequency, a power source regulating transformer 7 having a primary winding N.sub.1, a secondary winding N.sub.2 insulated from the primary winding N.sub.1, and a control winding at right angles to the primary and secondary windings, a controller 9 for controlling the controlling current of the power source regulating transformer 7 and a rectifying smoothing capacitor 8 determining the ripple voltage of the dc output voltage from the power source regulating transformer 7 in conjunction with the load power. With the switching power source device, the harmonic distortion in the ac input current is diminished and the ac input voltage is improved to a sinusoidal wave.

Abstract: There is provided a low-noise switching power supply for producing a regulated output voltage from an unregulated supply. The power supply includes a main transformer having first, second and third legs. A primary winding associated with a first leg produces an alternating magnetic flux in the core. A load winding associated with a second leg produces the output voltage from the power supply. A control winding is associated with the third leg. The regulated output voltage is compared to a reference voltage and used to operate a control circuit which alternately short circuits the control winding so as to vary the reluctance pass in the transformer and maintain the output voltage at a substantially constant predetermined value. A feedback circuit including a coupling transformer connects the primary coil to the switching circuit to improve regulation and provide a "soft start" capability.

Abstract: An inventive regulated high-voltage power supply circuit comprises a push-pull oscillation circuit (30) including two transistors (TR4, TR5), a control circuit (20) for controlling voltage to be supplied to the oscillation circuit, a short detecting circuit (50) for detecting shorting in the secondary side of a high-voltage transformer thereby to attenuate output voltage from the control circuit and a time-constant circuit (60) for maintaining an attenuated state of the output voltage of the control circuit caused by the short detecting circuit after releasing of the shorting for a prescribed period of time. Since the osccillation circuit is of the push-pull type, the same can oscillate over the entire periods of positive and negative halfwaves of the AC waveform, thereby to increase outputted power.

Abstract: Extremely high efficiency is achieved in a DC to DC converter by using a relaxation oscillator in which two transistors alternately conduct current to the primary winding of a step-up transformer. The transistors are interconnected by a resistor and capacitor in series so that when the converter is lightly loaded, the saturable reactor in the circuit will be self-resonant, so as to draw only minimal power from the battery source. The converter also includes a battery charge level monitor circuit that prevents the DC to DC converter from oscillating and thus providing power unless the battery is above a minimum charge level when its voltage is applied to the converter. In a preferred embodiment, the converter provides an output of up to 100 watts.

Abstract: The circuit includes an inverter to be connected to a source of d.c. power. The inverter has a transformer with a center-tapped primary winding. Separate controllable switching devices are connected to the respective ends of the primary winding. Both switching devices are arranged to be connected in common to one output terminal of the d.c. power source. The center tap of the transformer primary winding is arranged for connection to the other output terminal of the d.c. power source. The transformer has a laminated silicon steel core, and includes a secondary winding arranged for connection across the input terminals of a gaseous discharge lamp. A control circuit is connected to control conduction by the separate controllable switching devices in alternating sequence at a desired frequency of operation.

Abstract: A current driven gain controlled electronic ballast system (100) is provided having a power source (112) for actuating a pair of gas discharge tubes (140 and 140'). The ballast system (100) includes a filter network (111) which is connected to the power source (112) for establishing a substantially constant voltage signal and suppressing harmonic frequencies generated by the electronic ballast system (100). An induction circuit (115) is coupled to the filter network (111) for generating a voltage across the gas discharge tubes (140 and 140') responsive to the driving current. The induction circuit (115) includes an automatic gain control network (117) to maintain the driving current at a predetermined value and includes a trigger network (117) for generating a switching signal.

Abstract: A high voltage generator 1 for an electrostatic dust precipitator 2 comprises a low voltage oscillator 6, operating from a low voltage continuous source, such as a car battery, which supplies a current chopper 7. The output from the chopper 7 is fed to the primary winding 9 of an induction coil 10. The secondary winding 11 of the coil 10 is connected to one of a metal surface 3 of the dust precipitator to apply a high potential difference between the metal surfaces 3,4 to precipitate dust. Preferably the metal surface 3 is connected to the secondary winding 11 via a high voltage diode.

Abstract: A power supply for a magnetron is adapted to be powered from a regular power line and comprises an inverter means operable to provide an AC voltage of relatively high frequency. This relatively high-frequency AC voltage is applied to a step-up transformer, which transformer exhibits a relatively high leakage inductance between its input and output windings. A capacitor is connected across this transformer's output winding and effectively resonates with the internal inductance thereof. A rectifier and filter means is connected in parallel circuit with this capacitor, and provides an output of current-limited substantially constant-magnitude DC voltage for application to the magnetron. As a result, the magnetron is efficiently powered with a nearly constant DC voltage, as contrasted with the pulsed DC voltage normally used for powering magnetrons.

Abstract: A series regulator responds to an input voltage to produce a constant direct voltage. A resistor is connected at one end to the output of the regulator. A current carrying bus is connected between the other end of the resistor and the input of the inverter whereby current flows through the resistor producing a voltage drop thereacross and thereafter flows into the inverter to supply power thereto. An electronic switch has a closed position at which current on the bus supplied via the resistor is augmented by the current on the bus supplied via the switch. The switch has an open position at which the augmented current is not present on the bus, the switch being placed in the open position whenever a pulse appears in the control voltage and thereafter is placed in the closed position when the pulse disappears and said voltage drop is at least equal to a preselected value.

Abstract: A power supply circuit for driving a motor includes a rectifier circuit and a converter circuit for stepping down the DC voltage from the rectifier circuit to drive a motor. The power supply circuit further includes a regulator circuit which is energized by the DC output voltage from the converter circuit to supply a constant voltage or current to the motor.

Abstract: An electrical converter for supplying electrical power to a load from a d.c. source and which includes semi-conductor switching means for converting a direct input current to an alternating current and output transformer means fed with the alternating current for changing the magnitude of the output voltage with respect to the input voltage, wherein the semiconductor means includes transistor means connected with a drive transformer means in a configuration which provides for switching in response to saturation of at least a part of the drive transformer means, and the drive transformer means includes a winding connected in the main current circuit of the transistor means in a configuration providing current feed-back to a drive branch of the circuit connected to a control electrode of the transistor means to increase the response of the transistor means to drive signals derived from the input current and effectively provide a forced D.C.

Abstract: A high voltage power supply is formed by three discrete circuits (12, 14, 16) energized by a battery (18) to provide a plurality of concurrent output signals floating at a high output voltage on the order of several tens of kilovolts. Each circuit has a regulator stage (20, 28, 36). In the first two circuits, the regulator stages are pulse width modulated and include adjustable resistances (R1, R2) for varying the duty cycles of pulse trains provided to corresponding oscillator stages while the third regulator stage includes an adjustable resistance (R3) for varying the amplitude of a steady signal provided to a third oscillator stage.

Abstract: A regulated power supply has a synchronous detector in a voltage regulator feedback loop. The detector is coupled to a secondary of a transformer to detect the AC voltage. The result is faster response time to a step change in the primary voltage and all DC output voltages are constant.

Abstract: A multiple output d.c. to d.c. regulating circuit including an input protection circuit for providing protection against input overcurrent, input transient voltages, sustained input overvoltage and input polarity reversal. The protection circuit powers a d.c. to a.c. inverter which generates high frequency square-wave signals. The square-wave signals are fed to a magnetic saturable reactor regulator which has its controlled windings connected by a rectifying filtering network to a pair of main output terminals and connected by transformer rectifier filter circuits to a plurality of auxiliary output terminals. The d.c. output voltage across the main output terminals is sampled and is compared to a reference voltage of an integrated circuit operational amplifier. The output of the integrated circuit operational amplifier is connected to the control winding of the saturable reactor for controlling the controlled windings so that the square-wave signals are pulse width modulated to regulate the d.c.

Abstract: A Royer circuit, which includes an inverter and a saturating output transformer, is powered from a current source rather than from a voltage source, thereby reducing transistor current overshoot when the output transformer saturates. A current source inductor and a PWM (pulse width modulated) power transistor are series connected in the current return line of the inverter. The PWM power transistor emitter is connected so that potential between it and the common DC input power terminal will be low. This permits the PWM power transistor to be direct-coupled from a low voltage PWM switched mode power supply control circuit. A start-up circuit for supplying start-up power to inverter control circuitry from the DC input source is provided. Feedback loop control for the PWM power transistor is also provided.

Abstract: A variable leakage transformer or a variable voltage transformer comprising a magnetic core with a main magnetic path and a sub-magnetic path, the main magnetic path having at least a common magnetic path with the sub-magnetic path, a primary winding wound on said common magnetic path of the core, a secondary winding wound on said main magnetic path of the core, and means for controlling the magnetic flux in said sub-magnetic path. By controlling the magnetic flux in the sub-magnetic path, the leakage of the flux induced by the primary winding from the main magnetic path to the sub-magnetic path can be controlled, thus the coupling between the primary and secondary windings, and conduction period in each cycle of the AC output voltage are controlled. The control of the conduction period in each cycle provides the control of the power transmitted from the primary winding to the secondary winding.

Abstract: A transformer coupled, resonant feedback, tuned oscillator circuit in which the output current to a low power variable load is maintained constant by incorporating into the circuit an additional feedback circuit which provides a DC error voltage to the oscillator circuit enabling it to compensate for variations in core loss resistance, variations in load, and variations in other circuit parameters. The feedback circuit includes two separate electronic switches both of which are connected to a voltage averaging circuit and an error amplifier which compares the voltage of the averaging circuit against an adjustable reference voltage whereby the DC error voltage is generated and supplied to the center tap of the transformer feedback winding. Because oscillator transformer core resistance variations can be compensated for, the design of the oscillator transformer can be simplified and readily available, not specially designed, transformers can be utilized.

Abstract: A switching voltage regulator (86) is controlled to produce a low output voltage when the power is first turned on and subsequently to produce a high output voltage after a predetermined length of time has elapsed, thereby eliminating overloads due to initial surge currents.

Abstract: An electronic ballast for starting and operating gaseous discharge lamps from a low voltage d-c source which employs a regulated inverter providing controlled high ignition voltage, constant current warm-up and constant wattage operation for one or more lamps.

Abstract: A method and apparatus for regulating the luminous flux generated by a lamp with the degeneration of the voltage from a power source such as a battery. The regulating circuit maintains a constant luminous flux output from a lamp over a substantial range of voltages by switching the voltage to the lamp on and off at a preselected and controlled duty cycle. The principal advantage of this regulation is that only the minimum energy necessary to produce a required minimum luminous flux is used from the power sources irrespective of its voltage value within the operative range. The power pulses applied to the lamp are of a voltage that varies directly as the voltage variations of the power source and widths that vary as the inverse square of the voltage from the power source for maintaining a constant RMS voltage on the lamp and thereby constant light output flux.

Abstract: A method and apparatus for regulating the output flux generated by a lamp with the degeneration of the voltage from a power source such as a battery. The regulating circuit maintains a constant luminous flux output from a lamp over a substantial range of voltages by switching the voltage to the lamp on and off at a preselected and controlled duty cycle. The power pulses applied to the lamp have heights that vary directly as the voltage variations of the power source and widths that vary as the inverse square of the voltage from the power source for maintaining a constant RMS voltage on the lamp and thereby constant light output flux.

Abstract: A power supply apparatus is disclosed including a device for producing an oscillatory signal, and an output circuit for producing from said oscillatory signal an alternating-current output voltage, characterized by the provision of a regulating unit connected in series with the output circuit for producing a controllable voltage drop. The regulating unit includes a control device operable in response to a signal derived from the output circuit for controlling the voltage drop in response to a change in an output parameter of the output circuit.

Abstract: A regulated DC to DC power supply which minimizes input bus current changes caused by low frequency cyclical load variations is disclosed. The power supply includes a regulator connected to the input bus and controlled by a pulse width modulator. The regulator converts the DC voltage on the input bus to a higher, regulated DC voltage which is supplied to a variable load. A voltage feedback circuit is connected to the output of the boost converter and generates a control voltage which is supplied to the pulse width modulator to regulate the output voltage for variations in line voltage and load. The voltage feedback circuit includes an operational amplifier having a reference voltage supplied to a positive input terminal, and the output of the regulator supplied to a negative input terminal. A frequency response shaping network is connected between the output and the negative input terminal of the operational amplifier.

Abstract: A chopper circuit arrangement for charging an electronic flash discharge capacitor and for turning off the chopper is disclosed. The arrangement operates from a D.C. source and includes chopper transistors and a transformer operating together as a converter. Regenerative means, including a feedback winding of the transformer, function to charge the flash discharge capacitor. The arrangement includes transistors disposed across the chopper transistors to block or hold the converter off. These blocking transistors are activated when the voltage across the discharge capacitor has achieved a predetermined value. The arrangement includes means for effectuating blocking of the converter only during the off condition of the chopper. The arrangement also includes means for delaying the charge of the discharge capacitor, after discharge, for a predetermined time.

Abstract: A voltage stabilizer includes the series combination of a series regulator element and inductor and an inverter circuit connected across a direct voltage supply. The series regulator is controlled by a comparator which compares the stabilized output voltage with a reference voltage. A diode energized in the forward direction by inductive turn-off voltage appearing on the inductor is connected in shunt with the series combination of inductor and inverter circuit. A series combination of a diode energized in the forward direction by the inductive turn-off voltages appearing on the inductor and the parallel combination of a resistor and a capacitor may be connected in shunt with the input of the inverter circuit. The inverter may be of the push-pull parallel or bridge type. The inverter output may be inductively coupled with the series control element.