Showing papers on "Active load published in 1979"
Patent•
27 Sep 1979
TL;DR: In this article, a passive resistive bridge circuit has been proposed to regulate the magnitude of output current delivered to a load impedance connected across the output terminals by a current sensing resistor in one arm of the bridge.
Abstract: A -DC to +DC voltage converter having one input and one output terminal connected to ground and regulator circuitry responsive to a control voltage for regulating the magnitude of output current delivered to a load impedance connected across the output terminals. Apparatus producing the control voltage comprises a passive resistive bridge circuit having one pair of nodes connected between the other input and other output terminals and a current sensing resistor in one arm of the bridge so as to pass load current to the other output terminal, a difference voltage that is the control voltage being developed between the second pair of nodes of the bridge. In one embodiment, the bridge comprises a potentiometer having a moveable contact connected to the other input terminal, and first and second pairs of series connected resistors connected between opposite sides of the potentiometer and opposite sides of the current sensing resistor. The potentiometer is adjusted to make the difference voltage between junctions of resistors of the pairs thereof a desired value for a prescribed maximum load current in the current sensing resistor. In an alternate embodiment that is also responsive to input current, the potentiometer is replaced by fixed resistor connected to the other input terminal and having opposite sides thereof connected to ends of associated series connected resistors, one of the other resistors being variable for adjusting the bridge.
34 citations
Patent•
31 May 1979TL;DR: In this article, an improved IGFET bootstrap driver circuit was proposed to drive a load impedance to substantially full VDD power supply voltage and hold the load at that voltage for an indefinite period of time.
Abstract: An improved IGFET bootstrap driver circuit capable of driving a load impedance to substantially full VDD power supply voltage and holding the load at that voltage for an indefinite period of time. The circuit includes a load transistor, a feedback capacitor connected between the source and gate electrodes of the load transistor, a fix valued resistor connected between the gate electrode of the load transistor and an on-chip bias voltage generating circuit for providing a bias voltage greater than VDD+VT. The resistor and the bias voltage generating circuit provide sufficient current to replenish the charge lost from the feedback capacitor through junction leakage currents in the driver circuit. The resistor is of a sufficiently high value such that the current drain from the generating circuit is insignificantly small in comparison to the current drain from the VDD power supply. The improved circuit also permits the load transistor to be switched "on" or "off" by an externally applied signal.
20 citations
Patent•
28 Jun 1979TL;DR: In this article, a flip-flop comparator is used to respond to the current levels through an inductive load to generate high and low level outputs to connect and disconnect power to the load.
Abstract: Comparator means respond to the current levels through an inductive load to generate HIGH and LOW level outputs causing first switch means to connect and disconnect power to the load. When the load current initially exceeds a peak load actuation level, flip-flop means responsive to the corresponding change in comparator output levels change the current through an auxilliary sense resistor coupled to the sense input of the comparator means. In one embodiment, a one-shot multivibrator prevents a change in the current to the auxilliary sense resistor for a fixed period after the commencement of a load actuation signal. The subsequent HIGH and LOW comparator output levels are fed back to the comparator reference input to switch the reference voltage thereat so as to represent first and second levels of the current sufficient to maintain actuation of the load.
19 citations
Patent•
17 Aug 1979
TL;DR: In this paper, a drive circuit for an inductive load such as a synchronous motor responds to an analog signal representing a desired load current and an actual load current, selectively applies first and second potentials to the load.
Abstract: A drive circuit for an inductive load such as a synchronous motor responds to an analog signal representing a desired load current and an actual load current and selectively applies first and second potentials to the load. The circuit includes transistor switches for selectively connecting the load to the potentials in desired polarity and diode circuits for maintaining current flow through the load when the transistor switches are opened, thereby decaying the load current.
18 citations
Patent•
26 Jan 1979
TL;DR: In this article, a means and method are provided which correct for variations in an amplifier load such as a speaker by sensing the load current, developing a feedback signal related to the load, comparing this feedback signal with the amplifier program, and instantaneously adjusting the gain of the amplifier to compensate for load current deviations from the program applied to the amplifier.
Abstract: According to the present invention circuit means and method are provided which correct for variations in an amplifier load such as a speaker by sensing the load current, developing a feedback signal related to the load current, comparing this feedback signal with the amplifier program, and instantaneously adjusting the gain of the amplifier to compensate for load current deviations from the program applied to the amplifier. By this means the performance of the speaker or other load that is driven by the amplifier is positively controlled and forced to track accurately with the program applied to the amplifier despite such opposing factors as reactance or inertia of the load, whereby the acoustic or other load response is a substantially accurate reproduction of the program.
17 citations
Patent•
13 Nov 1979TL;DR: In this article, alternating current is supplied to an auxiliary load on a transit car from a power supply comprised of a DC-energized inverter and a synchronous machine coupled to the inverter.
Abstract: Alternating current is supplied to an auxiliary load on a transit car from a power supply comprised of a DC-energized inverter and a synchronous machine coupled to the inverter. The inverter supplies the alternating current requirements of the load up to the normal steady state load current magnitude. The synchronous machine stores kinetic energy when the load current load does not exceed its normal steady state magnitude, and converts kinetic energy into electrical energy to supply the load current requirements in excess of its normal steady-state load magnitude and to supply load current whenever the DC source-inverter connection is interrupted. Frequency and amplitude of load voltage are regulated by operator commands through control apparatus coupled to the inverter and the synchronous machine.
16 citations
Patent•
10 Nov 1979
TL;DR: In this article, the active layers of a semi-insulation substrate are separated and formed into mesa shape, the impurity concentration Np is uniform, the layers 31 is etched thin as t1, and t2>t1.
Abstract: PURPOSE:To make small the size of the inverter circuit, by making FET formed on the active layer thinned partially as normally open type driver and making the transistor formed at the thick active layer as active load. CONSTITUTION:The active layers 31, 32 of the semi-insulation substrate 33 are separated and formed into mesa shape, the impurity concentration Np is uniform, the layers 31 is etched thin as t1, and t2>t1. On the n type GaAs layers 31 and 32, the Al electrodes 37, 38 are placed, the ohmic electrodes 34 to 36 are placed on the layer 32, and they are connected to the pads 39 to 42 corresponding to the exposure of the substrate 33. When the layers 31 and 32 are taken as transistors Tr1 and Tr2, the diffusion potential to Al of the n type GaAs is taken as VB. Taking the unit charge as q, dielectric constant is taken as epsilon, and selection is made as t1< (2epsilonVB/qNd)<1/2t2, Tr1 is of normally open and Tr2 is of normally closed type. About 2mum only is the active load between the gate and source of Tr2 and the gate and drain to remarkably reduce the occupying area.
4 citations
Patent•
3 May 1979
TL;DR: In this article, the current of the load is monitored by measuring the voltage drop across a resistor located in series with the load, which acts as a monitoring member to keep the voltage low and/or constant with a variable load current.
Abstract: In the circuit arrangement, the current of the load is monitored by measuring the voltage drop across a resistor located in series with the load. In this arrangement, the voltage drop dependent on the operation state of the load (V) controls a switching element ((T) which actuates a monitoring member (M). To keep the voltage drop low and/or constant with a variable load current, a one-way or two-way semiconductor element (D1-D4) is provided as resistor. This saves additional circuit complexity.
2 citations
Patent•
21 Apr 1979
TL;DR: In this article, a resistor R4 to protect overcurrent is set up in a power circuit to perform stabilization by a transistor 3 and an abnormal oscillation detection section 8 is applied to the output section of an active load circuit 7 in the power amplifier which operates in high frequency, oscillator, etc.
Abstract: PURPOSE:To protect an element from the overcurrent owing to the abnormal oscillation of an active load circuit by setting up the detection means of an abnormal oscillation signal in the output section of the active load circuit which operates in high frequency and overlapping this signal with a current limit signal. CONSTITUTION:A resistor R4 to protect overcurrent is set up in a power circuit to perform stabilization by a transistor 3 and an abnormal oscillation detection section 8 is applied to the output section of an active load circuit 7 in a power amplifier which operates in high frequency, oscillator, etc.. When the active load circuit 7 generates abnormal oscillation in the frequencies other than required ones, this signal is detected by a band check filter 10 and drops the voltage of the load resistance R7 of a diode 9. It is applied to an operational amplifier 11 and turns off the transistor 3. Accordingly, the signal based on abnormal oscillation operates overlapping with a current limit signal. As a result, it accurately protects overcurrent and prevents an element from being destroyed.
Patent•
30 Mar 1979
Patent•
22 Feb 1979
TL;DR: In this article, the switching-on of a second stage load plugged into the first load is performed by the current consumed by a second-stage load plugged in to the first-stage.
Abstract: The switching-on is performed by the current consumed by a second stage load plugged into the first load. The circuit consists of load resistors (RL) across which a voltage drops when the second stage load (M2) is started and of a voltage comparator (OP1) the oscillating rectangular voltage of which is rectified by a diode (D3) and smoothed by a capacitor (C3). There is a series resistor (R2) through which the smoothed voltage excites a transistor (Tr1), which applies current to the first stage load (M1) through a make contact.