Showing papers on "Negative impedance converter published in 1983"

Load impedance detector for audio power amplifiers

Abstract: Disclosed is a load impedance detector for detecting a variation of the load impedance of a single-ended push-pull amplifier having a pair of first and second transistors, the emitters of which are interconnected by a pair of series-connected first and second resistors forming a first node to which the load impedance is connected Third and fourth resistors are connected in series to the emitter of the first transistor to form a bridge circuit with the first resistor and the load impedance so that the third and fourth resistors define a second node therebetween A voltage difference between the first and second nodes is detected by a differential circuit which is responsive to there being a simultaneous presence of a first state in which the detected voltage difference is higher than a first predetermined value and a second state in which the potential across the load impedance is higher than a second predetermined value for generating an output signal This output signal is utilized for controlling the level of the voltage supplied to the amplifier to compensate for the impedance variation

Power supply unit for electronic flash

Abstract: A power supply unit for electronic flash includes a converter drive circuit which is activated when a main switch is turned on or in response to the completion of a shutter operation or the completion of a film winding operation, thereby driving a converter for oscillation. The converter charges a main discharge capacitor to a given voltage, and when the given voltage is reached, the converter drive circuit is deactivated, thereby automatically ceasing the oscillation of the converter.

A Range of Body Impedance Values for Low Voltage, Low Source Impendance Systems of 60 HZ

Abstract: The severity of electric shock to humans from low voltage (60 Hz) low source impedance systems is dependent on many variables. These factors include the body impedance, current magnitude and duration, voltage and frequency of the circuit, and the current path traversed in the body. Several authors have investigated safe voltage and current limits that humans can withstand. As a result, thresholds have been established of the body's response to 60 Hz alternating current of a few milliamperes in low voltage systems. This report evaluates the many published findings as a means of recommending a range of body impedance values. While the authors have endeavored to present as comprehensive a review as possible, a subject of this nature precludes a completely exhaustive literary search.

Regulator for substrate voltage generator

Abstract: A regulated on-chip substrate-voltage generator circuit converts a single power supply input and ground potential into a negative potential. The negative potential is applied to the substrate of an integrated circuit upon which the substrate-voltage generator is formed. The substrate voltage generator includes a voltage oscillator connected to a charge pump device. A pair of depletion FETs forms a voltage divider circuit between the ground potential and the substrate potential. An amplifier, formed from depletion FETs, couples the voltage divider into the charge pump. The voltage divider and amplifier regulate the charge pump thereby maintaining tight control over the substrate voltage.

Ice deposition detector employing impedance change of a vibratory body

Abstract: A vibrating body is connected as one element of a voltage divider. A detector circuit is connected to the measuring point of the voltage divider. If ice is deposited on the body, its impedance changes and the resulting voltage change at the voltage divider is detected to provide an alarm or control function. The noted impedance change can be more reliably detected under a variety of conditions than the traditional vibration frequency or amplitude criteria.

Voltage regulating system for an electrical generator

Abstract: A voltage regulating system for a generator 10 that supplies the battery and electrical loads on a motor vehicle includes a load response control 40 for detecting whenever a substantial electrical load is applied to the generator tending to cause a drop in generator output voltage: when such a condition is detected, generator field current is controlled to gradually increase the field current from its prevailing value. The load response control includes means 164 for storing an electrical signal that corresponds to generator field current and for utilizing this stored value to set generator field current at a value corresponding to the value of field current that occurred just prior to the detected drop in voltage, and then increase the field current slowly from this value. The system also includes means 190,192 for preventing a subsequent drop in detected load voltage from actuating the load response control during the period that field current is being slowly increased by the load response control once it has been triggered by an initial drop in voltage.

Regulation characteristics of the digitally controlled DC-DC converter

Abstract: The output characteristics of the digitally controlled dc-dc converter is analyzed theoretically and experimentally and the regulation characteristics is steady-state is defined for the changes of the input voltage and the load. As a result, it is revealed that the regulation of the output voltage is often circumscribed within the comparative narrow ranges of the input voltage and the load, and that the circumscription of the regulation range is due to the overflow or the underflow phenomenon in the integral mode control circuit and can be satisfactorily extended by determining adequately the circuit parameters and variables in the digital feedback control circuit. Also, the transfer function between the small variations in the on-time interval of the switch and the output voltage of the dc-dc converter is defined, and then the proportional gain, the reset time and the rate time are approximately derived as a function of the proportional, integral and derivative (P-I-D) coefficients in the digital control circuit, respectively.

Floating battery feed circuit

Abstract: A floating battery feed circuit (10) comprising a switching-mode, flyback power converter (200) wherein a capacitor (C3) connected to a converter transformer winding (201) develops a relatively low voltage used to energize the converter control circuitry (100). The converter control circuitry prevents the operation of the battery feed circuit unless the voltage developed by the capacitor is above a predetermined magnitude. The power converter advantageously operates in only a constant-power mode regardless of loop impedance.

On chip voltage monitor and method for using same

Abstract: An on chip voltage monitor is provided for an integrated circuit having an analog to digital converter. In one form, the threshold voltage of a plurality of diode-connected test transistors is monitored by selectively positioning the transistors on an integrated circuit die. For each test transistor, a current source in response to a control circuit is selectively coupled thereto for sourcing predetermined amounts of current. The analog to digital converter in response to the control circuit is selectively coupled to the test transistor to measure the voltage across the test transistor. From this data, an accurate approximation of the threshold voltage may be made. Other voltages which are not easily externally measureable may be coupled to the on chip digital to analog converter for easy and accurate measurement.

Switching and negative capacitance in Al-Ge15Te81Sb2S2-Al devices

Abstract: A theory to explain the switching behaviour and variation of the capacitance with temperature and voltage, is proposed for vacuum evaporated metal-glass-metal devices. It is also shown that the observed capacitance of the device could be negative under voltage bias conditions. It is proposed that the voltage Vth at which the device changes from the off state to the on state and the transition voltage Vcn at which the capacitance of the device becomes negative should be related to the glass transition temperature Tg. A study of Al-Ge15Te81Sb2-Al devices reveals that the experimental results are in concurrence with the theoretical predictions.

Complete solutions of the transient behavior of a transmitting thickness‐mode piezoelectric transducer and their physical interpretations

Abstract: Full analytic solutions of the internal stress field and the radiated ultrasonic wave are obtained for a thickness‐mode piezoelectric transducer excited by a pulse voltage source, having or not having an internal resistance. Two mechanisms of transduction as well as the effect of the internal resistance on these are drawn from the complete solutions. The negative capacitance in the Mason equivalent circuit is interpreted in terms of the identified mechanism of the acoustoelectrical regenerative vibration.

Focusing voltage output circuit for cathode ray tube

Abstract: In a focusing voltage output circuit for a cathode ray tube, a variable impedance circuit is connected in series with a variable resistor for adjustment of focusing voltage. The impedance of the variable impedance circuit is changed in response to a video luminance signal or a beam current to change the focusing voltage so as to optimize the focus tracking characteristic.

D.C. voltage converter including a pulse width controlled semiconductor switch

Abstract: A d.c. voltage converter having alternating energy intake and energy discharge phases. The converter includes a power transformer having a core and at least primary, secondary and tertiary windings associated with the core. A primary circuit including a pulse width controlled semiconductor switch connected in series with the primary winding conducts an energy intake current during the energy intake phase of the converter. A secondary circuit including a smoothing capacitor and at least one rectifier element connecting the smoothing capacitor to the secondary winding conducts an energy discharge current during the energy discharge phase on the converter. Circuit means are provided for connecting the tertiary winding to the smoothing capacitor so that, following the energy discharge phase of the converter, excess energy of the smoothing capacitor in the form of an energy feedback current is fed back into the core until the start of the next energy intake phase of the converter.

Gain control circuit for obtaining a constant output signal amplitude by attenuating an input signal amplitude

Abstract: A gain control circuit is disclosed. In accordance with the preferred embodiment of the invention, a negative feedback amplifier is connected between a reference voltage and a variable impedance circuit which controls the voltage to the input of a signal amplifier whose output defines the desired output voltage. The variable impedance circuit varies the input voltage to the signal amplifier as a function of the level of the output voltage appearing at the output of the signal amplifier. The output impedance of the negative feedback amplifier is chosen such that an A.C. signal appearing at its output end can be sufficiently attenuated. As a result, the input impedance to the variable impedance circuit is negligibly small with respect to an A.C. signal. As a result, the amplitude of the input signal is varied over a wide range in response to the impedance of the variable impedance circuit.

Electronic switched-mode power supply

Abstract: The subject-matter of the invention is an electronic switched-mode power supply for the regulated power supply of an electrical load and of an AC or DC voltage source at a different voltage level. The electronic switched-mode power supply contains a flyback converter which is pulsed in a primary manner and in which the primary winding of a transformer is connected in series with a controllable semiconductor switch, and whose secondary winding is connected in series with an electrical load and a diode. The current-flowing phase of the controllable semiconductor switch is determined by means of a second controllable semiconductor switch whose selection is determined via the voltage which is dropped on an emitter impedance which is connected in series with the switching path of the first controllable semiconductor switch. The emitter impedance is composed of a fixed impedance and a controllable impedance, whose impedance value is determined via a low-pass filter which is connected in the connection between the switching path of the first controllable semiconductor switch and the load. The resulting total emitter impedance is thus increased as the operating voltage rises, the peak current is reduced, and the secondary current is hence made linear.

Current limit circuit in single-ended forward converter utilizing core reset to initiate power switch conduction

Abstract: Current limit protection against current overload is obtained in a core-reset, forward-type converter by inserting a properly selected impedance in the flyback current path. The voltage developed across the impedance is impressed against the secondary winding of the power transformer. During current overload, the voltage drop across the impedance maintains a voltage drop across the secondary winding delaying a zero crossing of the voltage and, hence, delaying the initialization of conduction in the converter power switch. The time delay in conduction initiation in the power switch reduces current output and effectively counteracts the overload current.

Voltage sensor device

Abstract: A hand held voltage sensor in which a low impedance test lamp mode or a high impedance voltage test mode is selectable via a thumb accessed slide switch. In the high impedance mode, three light emitting elements provide indication of the value of voltage potential between a probe conductor and an associated ground conductor being above, below or pulsing above an adjustable threshold level.

Monolithic integrated circuit device including AC negative feedback type high frequency amplifier circuit

Abstract: A monolithic integrated circuit device is formed on a substrate and made up of an AC negative feedback circuit for a high frequency amplifier circuit The AC negative feedback circuit includes a semiconductor impedance element and connected to an external terminal on the substrate, and variable control means for adjusting an amount of the AC feedback of the high frequency amplifier circuit As the semiconductor impedance element is used the junction capacitance of a diode under negative bias, diffusion capacitance between the base and emitter electrodes or between the base and collector electrodes of a transistor or a differentiated resistance of a diode

An input circuit for converting an a.c. input voltage to a logic level voltage

Abstract: The input circuit (10) includes a rectifier (12) for converting a sensed a.c. voltage which is supplied through a coupling impedance (20) to the light emitter (28) of an optical isolator (30). While the a.c. voltage is below a first predetermined voltage, a switchable low impedance circuit path (46, 48) in parallel with the light emitter is rendered conductive to maintain a low voltage across the light emitter to prevent it from becoming conductive until the sensed a.c. voltage reaches the predetermined voltage. A switchable high impedance circuit path (52, 54) in parallel with the low impedance circuit path (46,48) becomes conductive once the a.c. voltage reaches the first predetermined voltage to place a high voltage across the light emitter (28) to exhibit a sharp "turn-on". The high impedance circuit path (52, 54) remains conductive to keep the light emitter (28) energized until the a.c. voltage drops to a second predetermined voltage so that the light emitter exhibits a sharp "turn-off".

Load control for small power stations

Abstract: The load controller is especially suitable for a small power station having a hydroelectrically driven AC generator which is isolated from the public mains network. The AC generator (G) supplies a basic load impedence (ZG) and an additional load impedance (ZL), designed as an electrical heating apparatus, in which the excess energy which is instantaneously not required is consumed. A measuring element (M) generates a nominal voltage, which is proportional to the voltage on the basic load impedance (ZG), as a control variable for a controller (S) which, for its part, drives an AC power controller (W). When the basic load impedance (ZG) varies, the current through the additional load impedance (ZL) is regulated by phase-gating control in such a manner that a constant voltage is set on the basic load impedance (ZG).

Current source test circuitry

Abstract: A test circuit for determining the current produced by a current source device with a predetermined, non-zero voltage at the output of the device. The circuit includes a current to voltage converter circuit for converting the current produced by the current source device, typically a digital-to-analog converter (DAC), into a corresponding voltage. A control voltage source is coupled to the output of the current source device and to the current to voltage converter circuit through a coupling circuit. The coupling circuit couples a predetermined portion of the control voltage to the output of the current source device and to the current to voltage converter circuit with the voltage produced by the current to voltage converter being proportional to the current produced by the current source device and independent of the control voltage. With such an arrangement, the compliance voltage range of a DAC may be accurately measured. Further, the test circuit enables the non-linearity and relative accuracy of a DAC to be determined with the output of the DAC having a non-zero voltage at its output.

High voltage generating circuit for an automotive ignition system

Abstract: A high voltage generating circuit for an automotive ignition system, wherein a current control circuit is provided in series with an automotive battery and a controlled high frequency switch to generate a high frequency, linearly increasing ignition current across the electrodes of the spark plugs of an internal combustion engine in order to accommodate shifts in the spark plug sustaining voltage which may occur due to changes in operating conditions. In a preferred embodiment, a DC-DC converter is inserted in series between the battery and the current control circuit to step-up the voltage applied to the current control circuit.

Magneto-resistance effect type head reproduction circuit

Abstract: PURPOSE:To always keep the high reading quality and to improve both the yield and the lifetime of an MR head by using a means to detect the up/down amplitude of a reproduction waveform, a means to extract the difference voltage between detected upper and lower amplitudes and a means to control the external current value to minimize said difference in voltage. CONSTITUTION:A voltage difference detecting circuit 12 using an operational amplifier supplies the envelope voltages of both positive and negative polarity sides and produces the voltage difference between both voltages to the output. This voltage difference is digitized and sent to a microprocessor 14. The processor 14 can know the difference between upper and lower amplitudes of a reproduction waveform with a signal and then transmits a signal indicating the current value to a register 15 under the proper conditions and based on the prescribed judgement. The current value set to the register 15 is transferred to a D/A converter 16 under the control of the processor 14 and converted into the voltage. This voltage is applied to the base of a current source transistor 2, and the current value to be given to an MR head is varied with the change of said voltage. This current value is previously set at such a level that minimizes the difference between the upper and lower amplitudes. Thus, the waveform distortion can be minimized.

Method of controlling supply of fuel and oxidizing agent

Abstract: PURPOSE:To minimize voltage fluctuation by supplying fuel and oxidizing agent when inclination similar to that of a load current - cell voltage curve is provided and the set value of such a voltage setting curve as located at the lower side of the curve is compared with the cell voltage and the difference becomes larger than the predetermined value. CONSTITUTION:A control voltage set value C is made to be the same or similar to an inclination of a load current - cell voltage curve A. The set value C is expressed in the formula Vr-K.r.IL. Provided that, Vr is a set voltage when the load current is 0A, IL is the load current, r is a current detecting resistance and k is a constant which makes partial pressure of the voltage on both ends of current detecting resistance. Therefore, Vr-k.r.IL is compared with the cell voltage and when the difference becomes larger than the predetermined value, fuel and oxidizing agent are supplied. Then, cell performance with less voltage fluctuation can be obtained even when the load current is fluctuated.

Integrated circuit voltage multiplier

Abstract: A voltage multiplier circuit includes an n-type substrate (10) provided with a pair of isolated p-type regions containing respective negative and positive voltage multipliers (20, 21) which include respective pluralities of conductor-insulator-semiconductor diodes (Q1---Qm; Q'1---Q'm) and respective pluralities of paralled polysilicon plate capacitors (C1---Cn; C'1---C'n). The outputs of the voltage multipliers (20, 21) are coupled together. Located in a further p-type region (11'') is an auxiliary negative voltage multiplier (22) having its output coupled to the p-type regions and providing a negative output voltage of greater magnitude than that of the main negative voltage multiplier (20). The turn-on tendency of parasitic transistors in the main negative voltage multiplier (20) is thus reduced, enabling a high operating temperature range of up to 150oC and short fall time for the main negative voltage multiplier (20) to be achieved. The p-type regions may be formed by a single epitaxial region or well in the substrate (10).

Change system for vehicle battery with relay actuated charge indicator

Abstract: A charging system for a vehicle battery comprises a voltage detecting circuit having at least one element, such as a Zener diode, having an impedance variable in accordance with a voltage from an auxiliary rectifier connected to the armature coils of the alternator of the system. When the generating voltage is low at the initial operating period, the impedance of the voltage detecting circuit is kept high, and thus the generated current from the auxiliary rectifier is all supplied to the field coil of the alternator without being consumed by a driving circuit of a charge-indicating lamp. As the voltage from the auxiliary rectifier exceeds a predetermined voltage, the impedance of the detecting circuit lowers to cause the driving circuit to energize the lamp. The voltage detecting circuit may be constructed of one or more than one Zener diode, or of a plurality of diodes connected in the forward direction. The driving circuit may be a relay or a semiconductor switch, and is driven by a current from either the auxiliary rectifier or the battery.

State of the Art in DC-to-DC Converters

Abstract: A survey on the state of the arts in the dc-to-dc converter is presented. A number of important problems underlying the converter are classified into two categories, one is solvable by the averaging method and the other is not. In general, the converter circuit itself should be stable in order to reduce the size of the converter by making its switching frequency high. As examples of size reduction, we show three kinds of converter circuit techniques in which magnetics plays a key role. The first deals with a high frequency magnetic amplifier to suppress the current surge in high speed switching, the second with a ferro-resonant circuit driven by a high frequency inverter and the third with a high frequency converter of megahertz order which is based on a multi-vibrator. In these examples, we show that the amorphous core is effectively used for magnetic components.

Method for the pulse-width modulated operation of a converter-supplied rotating-field machine

Abstract: The rotating-field machine (1) is supplied from the R, Y, B mains via a DC intermediate circuit converter, whose converter (2) on the machine side, as a pulse invertor, emits a sinusoidal current to the rotating-field machine. The maximum terminal voltage of the rotating-filled machine is equal to the mains voltage and is achieved in that the intermediate circuit capacitor (3) is charged up beyond the mains voltage. To this end, the converter (4) on the mains side is constructed as a three-phase bridge circuit consisting of valve devices (V1-V6) which have a diode characteristic in each case in one direction (diodes D1 to D6), but whose current supply in the other direction can be switched on and off (switches S1 to S6). A nominal current value, synchronised to the phase voltage and having an upper and lower tolerance limit I- , I+ , is specified for each phase current. Input inductors L force the phase current to flow alternately with a negative or positive gradient when the valve devices are pulsed. In consequence, the current is guided within the tolerance band. By specifying the amplitude of the nominal current value, the intermediate circuit voltage (Ud) can be regulated to the desired high level.

A circuit for a high impedance signal source

Abstract: An amplifier having a high input impedance and a low output impedance in the voice band. The circuit comprises an input coupling circuit (101a) and a similar coupling circuit (101b), source of reference direct current voltage (103), and a gain providing circuit (102). The coupling circuits (101a and 101b) comprise a first pair of diodes (Q1 and Q2) symmetrically placed about one input terminal (IN1). Outputs of the reference voltage source (103) are provided to coupling circuits (101a and 101b) and through the coupling circuits to a gain providing circuit (102). Such an arrangement facilitates power supply noise rejection and automatic cancelling of direct current voltage drifts.

Shielded electrical cable system

Abstract: Shield of telecommunications cable is grounded through negative impedance converter to reduce induced voltage in conductors in the cable caused by electromagnetic field of nearby powerline