Showing papers on "Inductor published in 1977"

High efficiency DC to DC converter

Abstract: A DC to DC converter has an unregulated input and provides a pair of regulated outputs which independently provide variable power on demand to two independent loads at a substantially constant output voltage. The converter includes three major sections, the input oscillator and pulse width modulation section, the isolated negative DC regulator and the isolated positive DC regulator. Each of the DC regulators is current limited and each is provided with overvoltage protection. One of the output regulators provides improved efficiency through the use of a pair of appropriately connected catch diodes which decrease current change through a filtering inductor, and through implementation of a combined regulator preload resistor and AC pulse width modulating switching transistor drive current source. The converter is a compact modular unit having a low profile with circuit components arranged to minimize temperature instability.

How to improve system stability without risking subsynchronous resonance

Abstract: Various static devices for raising the stability limit of a power system are examined with respect to their employment at or near the electrical center of a two-machine system. Among these devices are series capacitors, shunt capacitors, combined series and shunt capacitors, and shunt static reactive compensators consisting of a fixed capacitor and a variable reactor. New concepts of current gain, voltage gain, and power gain are defined and illustrated. The natural frequencies of each circuit are examined, and it is shown that with series capacitors these frequencies are subsynchronous and hence produce a risk of subsynchronous resonance, whereas all shunt-connected devices give supersynchronous natural frequencies and therefore do not involve such a risk.

Electrical energy conversion systems

Abstract: Electrical circuits, apparatus and methods for a variety of applications. A switching device subdivides an alternating current input signal into a plurality of lower voltage pulses by switching on and off in response to the characteristics, such as the voltage and current, of the input signal, and the pulses of current are intermittently passed to a capacitor in series with the device as the voltage on the input signal is positive-going. When the voltage becomes negative-going, the capacitor is discharged, usually with the pulses passing through the switch in the opposite direction. Work is done by energizing the series capacitor, or by energizing a capacitor in parallel with the switch, or by energizing an inductor in parallel or series relation to the switch, or a combination of the above. The inductor may be the primary winding of a transformer, or may create an electrical or magnetic field which is transduced into mechanical motion. The load may also be a resistive load. Where a tranformer is provided, the output of the secondary may be used as a power supply, with or without additional filtration. The transformer may have a unity turns ratio, or may step the voltage up or down as desired. Where the device is used as a power supply, and in other applications, a direct or alternating current output is provided which can be very carefully controlled as to voltage with minimum circuitry being necessary to accomplish this purpose.

Communication circuit with combined power feed and data transmission over a phantom channel

Abstract: The disclosure relates to a four conductor circuit arrangement providing two communication channels between a control unit and a terminal device. Power feed and bi-directional signalling are accomplished simultaneously over the same four conductors used for the two commmunication channels without interference. The signalling from the control unit to the terminal is accomplished by means of a voltage modulator circuit in the control unit by which voltage pulses are transmitted via a phantom circuit arrangement over the four conductors to the terminal unit. The voltage pulses are sensed from the phantom circuit in a data receiver which is located at the terminal unit. Connected to the phantom circuit in the terminal unit is a voltage regulator circuit which receives power from the control unit via the four conductor phantom circuit interconnecting the control unit and the terminal. In series with the voltage regulator circuit is a constant current sink and an inductor. A current modulator circuit is provided in parallel for impressing current data pulses generated in the terminal onto the phantom circuit, which are, in turn, received by a receiver circuit in the control unit. A preferred data format is disclosed as a method for transmitting information between the control unit and the terminal. The preferred embodiment for the disclosed four conductor communication circuit and the disclosed data format is in a key telephone system in which the control unit is a station card in a key service unit and the terminal is a key telephone station set.

Drive circuits for a piezoelectric stack

Abstract: A drive circuit for a piezo-electric crystal stack comprises an inductor, a first circuit including a diode and a transistor through which the inductor can be connected to a pair of d.c. supply terminals, the first circuit including a switch operable to reduce the current flow through the inductor, a second curcuit including a diode through which energy from the inductor is transferred to the stack of crystals when the current flow through the inductor is reduced. The drive circuit also includes means for transferring energy from the stack of crystals to the inductor when it is required to increase current flow in the inductor.

Package for push-pull semiconductor devices

Abstract: A semiconductor package for containing two individual devices such that they may be externally connected in a push-pull relationship. Two transistors, each having an input and output pad are formed on the same dielectric wafer, in a spaced relationship with each other and a ground plane so as to form two separate transmission line paths. The transistors are wired either in a grounded emitter or grounded base configuration. A shunt inductor is formed by a metallized strip or lead bond from the collector of one transistor to the collector of the other transistor. This inductor reduces the influence of the parasitic capacitance in the equivalent output circuit of the transistors. Since the collectors of both transistors are at the same DC level it is not necessary to include a DC blocking capacitor in series with the inductor. This increases the reliability and the reproducibility of the circuit because bonding wires necessary in prior devices to connect the blocking capacitor in series with the output inductance is not necessary. This packaging technique increases the output impedance, decreases the internal losses, and increases the bandwidth when wired as a push-pull circuit.

Inductor for working metals by pressure of pulsating magnetic field

Abstract: Disclosure is made of an inductor for working metals by the pressure of a pulsating magnetic field, which comprises a magnetic field concentrator with an insulating slot. The concentrator has a cylindrical surface, whereon there is arranged a winding which induces eddy currents in the concentrator, and a surface, whereon there are concentrated eddy currents which induce eddy currents in the workpiece. The concentrator is provided with a conducting compensation rod overlapping the insulating slot, which rod is insulated from the concentrator and received in an opening extending along the slot in immediate proximity to that surface of the concentrator where there are induced eddy currents which induce eddy currents in the workpiece. The proposed inductor design makes it possible to produce a uniform magnetic field which, in turn, produces electrodynamic forces that work a blank so as to improve the quality of products, as compared to conventional working techniques.

Inductor simulation using a current conveyor

Abstract: Two schemes of simulating grounded inductors using a second generation current conveyor are reported. Both schemes provide simulated inductors that are relatively frequency independent, with suitable design, at moderately high-Q values.

Inductor for forming metals by the pressure of a pulsed magnetic field

Abstract: An inductor for forming metals by the pressure of a pulsed magnetic field comprises a magnetic field concentrator with a coil inducing eddy currents therein, the concentrator being made up of electrically insulated dies with an opening for the workpiece, so arranged that the plane in which the concentrator is split extends along said opening. Such a design of the inductor permits improving the power characteristics thereof, simplifies its operation, extends its service life, and enhances its efficiency. It also permits forming a wide variety of components.

Design, Measurement and Application of Lumped Elements up to J-Band

Abstract: Lumped-element design, fabrication and characterization has been extended for MIC requirements up to l8GHz. Spiral or loop inductors and overlay or interdigital capacitors have been measured at appropriate frequencies leading to satisfactory equivalent circuits. Variations in parasitic reactances and Q-factor with frequency, substrate dielectric constant and component geometry are presented. Particular applications include filter networks and FET amplifier matching circuits, the latter enabling octave coverage amplifier modules over X and J-band frequencies to be realised.

Power supply with pulse modulated control circuit - has voltage rectified via self inductor during switching phase of transistor

Abstract: The mains connected supply system has a switching transistor and a control and regulating circuit which has a pulse width modulating stage which reacts to the ratio between the desired and actual value. It also contains an overload protection circuit which limits the switching transistor when a predetermined energy storage current is reached. This achievement is a voltage supply for a t.v. receiver. A voltage is rectified (27) via the self-induction of the power supply during the transmission phase of the switching transistor (6). This is used to generate the supply voltage for the remote control circuit (6). The circuit contains a resistance matrix in the pulse width modulation stage which produces a negative current to reduce the voltage of the remote control circuit.

Electromagnetic induction heater for culinary use - uses rectangular windings arranged on cylindrical support with adjacent windows producing phase opposed fields

Abstract: The electromagnetic inductor for heating by induction has n elementary inductors arranged side by side when n is at least equal to 2. The n elementary inductors are wound and connected to an alternating source so that two adjacent inductors produce magnetic fields in phase opposition. The inductors are are also arranged with respect to each other so that at least a part of the magnetic flux leaving one of them returns through the inductor or induction surrounding it. The n identical elementary inductors are aligned on the same electrically insulating material support. The inductors are in the form of rectangular windings (71). The support (72) is cylindrical.

Microwave signal amplifier

Abstract: A microwave signal amplifier comprising transistor having input and output terminals further includes input and output matching circuits connected to the input and output terminals, respectively, and corresponding bias supply circuits connected in parallel between said transistor and said input and output matching circuits, respectively. The input and output matching circuits are each implemented by high pass filters, and the bias supply circuits are each implemented by low pass filters. Furthermore, said high pass and low pass filters respectively have capacitors and inductors connected to the transistor, and said low pass filters have termination resistors.

Resonant switching converter

Abstract: A DC to DC converter employs resonant switching to turn switching power devices on and off at zero current. Two series resonant circuits are formed by two inductors connected in series between a voltage source and a power switch and a capacitor connected between the junction of the two inductors and a source of reference potential. The values of the two inductors are chosen so that the natural resonant frequency of the second inductor and the capacitor is high compared to the natural resonant frequency of the first inductor and the capacitor. The power switch may be a semiconductor switch, such as a silicon controlled rectifier or a junction transistor. Both non-isolated and isolated outputs may be provided in buck or boost conversion. The converter can be used as a voltage regulator by the addition of output sensing, comparison with a reference voltage, and suitable on-off control.

Filter device for high frequency generating device

Abstract: A magnetron includes a high frequency generating source having an anode and a cathode, two power supply conductors for supplying electric power to the cathode of the high frequency generating source, filter circuits inserted in the power supply conductors for damping and suppressing the high frequency components leaking through the power supply conductors and a shield box covering the two power supply conductors and two filter circuits. Each of the filter circuits includes a capacitor and a choke which is comprised of an coreless type inductor made of coreless coil and a core type inductor made of ferrite-cored coil. The coreless type inductors of two filter circuits connected to the respective different power supply conductors are different each other in inductance.

High voltage transformer and process for making same

Abstract: High voltage solid dielectric insulation system transformers and inductors have been designed and produced by a process which results in a substantial improvement in the high voltage, size and weight characteristics of magnetic components prepared therefrom.

Some new lossless floating inductance circuits

Abstract: Two circuits containing only two operational amplifiers, one capacitor, and several resistors for simulating a lossless floating inductance are presented. The Q-value of several hundreds is easily obtained using these circuits. Experimental values agree well with the theoretical results.

Testing of inductively loaded transmission lines for correct loading

Abstract: Equipment and methods are disclosed for testing inductively loaded telephone lines for loading irregularities. In brief, immittance magnitude measurements are used to determine the approximate frequencies of the poles and zeros of such a line and then a lossless ladder network comprising series inductors and shunt capacitors is synthesized wherein the pole and zero frequencies of the network are substantially equal to those previously determined. The network inductor values relate to the line loading inductor values while the network capacitor values relate to the distances between the loading inductors.

Shield for electromagnetic continuous casting system

Abstract: A shield to be used in an electromagnetic continuous casting system comprises segmental strips forming a segmented, tubularly-shaped shield encircling a casting station and being positioned between molten metal being cast and an electromagnetic inductor

Fault current limiter

Abstract: A current limiting network is connected in a power line between an AC power supply and a load, and has a pair of series connected resonant branch circuits, each of which include a capacitance and an inductance tuned to the power supply frequency. Under normal operation virtually no impedance is offered by the network. Each branch circuit has a circuit node between the capacitor and inductor contained therein. A switch, having a resistance in series therewith, is connected between the circuit nodes in the branch circuits. The branch circuits are connected in parallel, and a resistance is connected in parallel with the branch circuits. The switch is responsive to a fault current in the power system and when actuated, detunes the series resonant branch circuits to thereby present a high impedance to the power line. The parallel resistance reduces the level of any transient surges and the time of any oscillation appearing on the capacitors when the switch is actuated by a fault current. Another embodiment selectively suppresses transients and reduces oscillation on the branch circuit capacitors.

High-speed, laminated rotor for homopolar inductor alternator

Abstract: In a high-speed homopolar inductor alternator rotor, formed laminations are employed to reduce eddy current losses in the pole faces The lamination configuration keeps magnetic path reluctance to a minimum, while also reducing leakage flux, since each lamination, in extending from a pole face where flux enters the rotor to a pole face where it exits, passes through a region radially-inward of the salient poles, while presenting a minimum of magnetic material in a position to contribute to unwanted leakage flux

Magnetic head employing easy axis thin film inductor

Abstract: A flux-sensitive magnetic head employs, at its back part, a structure having a thin single domain magnetic film coated thereon. A first coil wraps around the coated structure; and a second coil wraps around one pole of the head. A direct current is passed through the second coil, thereby to apply an easy axis magnetic bias to the film. By appropriately contouring the back gap of the head, signal flux appearing at the head front gap asserts a differential magnetic force to the easy axis of the film, thereby causing the inductance of the first coil to vary detectably.

Tap changing voltage regulator which eliminates preventive autotransformer

Abstract: Tap changer voltage regulating apparatus permits a tap changer selector contact to engage an open-circuited new tap without arcing and has a half-tap voltage auxiliary winding which permits halving the voltage being interrupted and doubling the number of steps and also has an auxiliary switch which initially connects the selector contact on the new tap in series with a circulating current-limiting inductor and the load to prevent load circuit interruption and then opens the previous tap circuit so that circulating current is interrupted at reduced voltage and then short circuits the inductor to complete the tap change, whereby the inductor is energized only momentarily.

Inductor-less, capacitor-less state-variable electrothermal filters

Abstract: Electrothermal circuits (ETC) exploit interactions between thermal and electronic properties of devices in an integrated circuit to perform useful electronic functions. An ETC integrator is described which can be used as a building block for state-variable filters. Circuits are given which perform the coefficient-setting function for such filters. Measured data are given for low-pass, high-pass, bandpass, and notch state-variable ETC filters; these filters use only transistors and resistors. For the chip size used, the maximum frequency of the filters is of the order of 200 Hz; an order of magnitude increase is possible with reduced chip size. Methods are described for making filter performance independent of ambient temperature.

Proximity detection system utilizing a movable magnet for saturating an inductor core wherein the rise time of a plurality of such inductors are compared

Abstract: Apparatus and method is disclosed for determining the position of a mechanical part from among a plurality of discrete positions. An inductor with a saturable core is placed in proximity to each position so that a permanent magnet attached to the part saturates only the core nearest the part, thereby reducing the inductance of that particular inductor. The variation in inductances are detected by comparing voltage rise times across a current limiting resistor serially connected to each inductor. The voltage across the resistor connected to the inductor nearest the position of the part will have the shortest rise time. In a two position embodiment, the variation in rise times is detected by a R/S flip-flop with each input coupled to one each of the inductors.

Light control device for high frequency lighted fluorescent lamp

Abstract: A light control device for a high frequency lighted fluorescent lamp includes a high frequency variable voltage power source. A first impedance element (a capacitor and inductor in series) is provided between the terminals of the lamp on the side opposite to the power source. A second impedance element (an inductor) is connected between the power source and the terminals of the lamp, and a third impedance element (a capacitor) is connected across the lamp on the power source side. A constant power source circuit supplies, upon starting of the lamp, constant power to the first impedance element to thereby apply substantially constant cathode pre-heating current and starting voltage and applies, during the lighting of the lamp, substantially constant cathode heating current. The control circuit is capable of pre-set light control. The light control device suppresses beat interference and fluorescent lamp noises due to the electric field radiated from the lamp. Rapid and instant starting is enabled. The solid state ballast is suitable for fluorescent lamp appliances for domestic use and permits use as an emergency lamp.

Balanced source follower amplifier

Abstract: A low distortion audio amplifier utilizes a pair of field effect transistors connected in a balanced source follower configuration. A tapped inductor connected between the sources of the field effect transistors provides inductive coupling between the sources and maintains the sources at the same direct current potential. This permits the voice coil of a loud speaker to be connected directly across the sources without causing excessive direct current to flow through the voice coil.

Thrush current start-up circuit for a television receiver including a start-up decoupling circuit

Abstract: A start-up circuit for a television receiver includes a circuit for rectifying the AC line voltage and a filter for providing a smoothed DC voltage. When the receiver is turned on, an initial interval exists in which an inrush current flows into the filter. A winding, magnetically coupled to an inductor in the path of the inrush current, develops an alternating current potential during the initial interval. This potential is rectified and provides a start-up operating voltage for the television receiver load circuits. During the steady state interval, a second circuit provides the operating voltage, and a third circuit couples to the winding a voltage which varies in value from the initial interval to the steady state interval in a manner which decouples the alternating current potential from the load circuits during the entirety of the steady state interval.

Circuit for providing saw-tooth current in a coil

Abstract: A circuit for providing a saw-tooth current in a coil is described. The circuit comprises a trace condenser and a retrace condenser which form together with the coil a resonant circuit during the retrace interval, a diode connected parallel to the retrace condenser, a controllable switch connected to a supply source through an inductor and to the retrace condenser through a second diode. The main feature of this circuit is to comprise a condenser connected on one hand towards the controllable switch and the first inductor and, on the other hand, to a circuit comprising a second inductor and, through a third diode, towards the retrace condenser. The condenser and the two inductors are sized in such a manner that when the controllable switch is not conductive, energy is supplied to the condenser and that successively, when the controllable switch is conductive, the condenser is completely discharged through the second inductor. The energy thus stored in the second inductor is then supplied to a storage device.

Control circuit arrangement for laser aiming system having magnetic decoupling means

Abstract: A control circuit arrangement for a laser aiming system for aiming a weapon or firearm is characterized by a laser head operable to generate a coherent beam of light energy useful to assist in aiming a weapon. The laser head includes a high voltage power supply having positive and negative terminals thereon. A source of D.C. electrical potential is connected to the first and second terminals. Magnetically responsive reed switches are serially connected between the source and each of the positive and negative terminals. An inductor is connected in series intermediate each of the magnetically responsive switches and the terminals to magnetically decouple the switches from the high voltage power supply and limit the intensity of magnetic fields induced by switching transient signals from the high voltage power supply.