Abstract: An overload detecting circuit for a PWM amplifier includes an output current detecting circuit and an output voltage detecting circuit. The output of the output voltage detecting circuit is supplied to a rectifying circuit having a discharge time constant determined by the cut-off frequency of a low pass filter as a demodulator of the PWM amplifier. A comparison circuit is provided to produce an overload indicative signal in response to the comparison result between the outputs of the rectifying circuit and of the output current detecting circuit.

Abstract: A self-biasing amplifier stage including a first transistor arranged as a common emitter amplifier. A current amplifier is connected for receiving collector current from the first transistor responsive to which an output current is provided which is differentially summed with a constant current. The resultant difference current is integrated to generate a potential which potential is applied via a potential follower to the emitter electrode of the first transistor to adjust the current therethrough.

Abstract: A light-emitting diode of a photo-coupler is energized and de-energized through a connection to a switching means. Radiation from the light-emitting diode directed toward a photosensitive means of the photocoupler, reduces the resistance of the photosensitive means to rendering a switching transistor conductive. The switching transistor is connected to and controlled by the photosensitive means. When the switching means is open, the switching transistor remains conductive for a predetermined time period due to a transient phenomena of a resistance change of the photosensitive resistor.

Abstract: A remotely powered intermediate amplifier for communications transmission incorporates two sectional amplifiers and a filter circuit interconnecting the output of the first sectional amplifier with the input of the second sectional amplifier.

Abstract: Improved slew recovery in a composite driving amplifier for driving a substantially reactive load including a feedback loop to the operational amplifier from the load for regulating the output of the amplifier, the composite amplifier has a predetermined resistance R1 in the feedback loop and includes a second feedback loop having a predetermined resistance R2. The second feedback loop extends from the output of the operational amplifier to the negative input and is substantially parallel with the first-mentioned feedback loop. To maximize the recovery of the amplifier from a slew condition, the relationship of R1-R2 should be as follows: ##EQU1## wherein: V.sub.o is the output voltage in the amplifier.Slope, is the slope of the load voltage curve during the overload condition, andDelay represents the period of time it takes the overload operational amplifier to respond to a feedback signal at a given overload condition.

Abstract: A variable gain controller comprising an amplifier having a feed back terminal which is connected to a variable resistor including a current controller for controlling current flowing through the variable resistor, a filter connected to the variable resistor for attenuating frequency components of input signals in accordance with the values of the variable resistor and a resistor inserted between output terminal of the amplifier and the connection of the variable resistor to the filter.

Abstract: A pulse width modulated signal amplifier comprises a DC power supply for rectifying an AC input voltage to produce a pair of DC voltages of opposite polarity, a pulse width modulated signal amplifying circuit supplied with a pulse width modulated signal to produce a demodulated signal through a low pass filter, and a detecting circuit responsive to an abnormal level of the DC voltages to produce a detecting signal when a smoothing condenser of the DC power supply is overcharged by a current flowing through the low pass filter in one direction. Such detecting signal is desirably employed to prevent the appearance of the output signal from the pulse width modulated amplifying circuit.

Abstract: A high frequency push-pull amplifier which includes an improved output circuit to eliminate spurious emissions, typically low frequency parametric oscillations. The output circuit includes a low pass filter with an inductive input so as to avoid a series resonance to any harmonic of the desired output signal of the amplifier. A resistive termination is provided to any of the in phase signal components between the push-pull amplifier and the low pass filter. Also, to inhibit any tendency towards parametric oscillations, the variation in output capacitance with respect to collector voltage of the transistors is minimized by placing a capacitor in parallel with the collector capacitance, which is several times the collector to emitter capacitance of the transistors at their normal collector voltage.

Abstract: A transistor amplifier comprises an input stage circuit and an output stage circuit direct-coupled to the input stage circuit: the input stage including complimentary paired transistors having bases commonly connected to an input terminal and emitters AC-wise grounded and further connected to constant current sources, respectively; the output stage being a single-ended push-pull amplifier circuit including complimentary paired transistors having bases connected to collectors of the input stage transistors, respectively, and emitters commonly connected to an output terminal. This transistor amplifier has advantages that it is simple in arrangement and that both its DC and AC operations are highly stabilized against variations in the ambient temperature and in the voltages of operating power supplies.

Abstract: A circuit permits the output voltage of an amplifier to be limited for certain ranges of its input voltage by causing the amplifier to saturate for said ranges of its input voltage by reducing the power supply.The invention is applicable, for example, to eliminating or levelling the components of a signal whose amplitude lies within a certain range, without affecting any other components.

Abstract: The present invention concerns the transmission of information, and consists in a continuous regulator responsive to the amplitude of a pilot tone included in the signal whose level is to be regulated, including a variable-gain quadripole through which said signal is passed, an automatic gain control loop including a circuit controlling the gain of the quadripole, and an auxiliary feedback loop through which the control circuit also controls the automatic gain control loop. The regulator is applicable with advantage to transmission systems.

Abstract: The circuitry is arranged to develop a highly accurate and stable reference electric level voltage and/or current for distribution to a plurality of logical circuits on a semiconductor chip having of the order of a thousand such circuits thereon. An input reference voltage is developed by a source reference circuit and applied to an operational amplifier circuit having "evener" circuitry for substantially equalizing the currents in the input transistors. This evener circuitry is essentially an operational amplifier within an op-amp. It monitors and adjusts feedback voltages. The operational amplifier and evener circuitry drives a reference voltage distribution grid laid out over the semiconductor chip.

Abstract: The present invention relates to an optical-electrical system for monitoring filaments etc. of narrow, fine configuration by means of an optical sensor, which includes one light guide mounted between a light source and the region monitored in which the filament is disposed, and another light guide between the monitored region and a photodetector.

Abstract: A bi-state linear amplifier is provided which, in response to a first state of a control signal, functions as a linear amplifier, and in response to a second state of a control signal, is cut off to define a high output impedance. The amplifier includes a control circuit responsive to relatively low-current control signals for selectively opening and closing the internal amplification circuit of the amplifier.

Abstract: A device for controlling the termination of light emission by a flash device including means for detecting the light reflected from the subject being illuminated by the flash, integrating means connected to the detecting means for providing a flash termination signal when the total amount of light received by the detecting means reaches a predetermined value, and flash termination means connected to the integrating device and to the flash device for terminating the delivery of electrical energy to the flash device when the signal from the integrating device reaches its predetermined value. The flash termination device is preferably constituted by a novel gas-filled, arc-producing element having identical, unpolarized electrodes and an internal or external triggering electrode.

Abstract: In a push-pull power amplifier which amplifies an audio-frequency signal supplied thereto and supplies its output signal to a load, a pair of output transistors constituting the push-pull circuit are alternately turned on and off according to the polarity of the input signal. In the power amplifier, current flowing through the current path leading from a DC power source to each of the output transistors includes many harmonic components besides its fundamental wave component. These harmonic components of current are introduced through a stray magnetic field into the signal path in the power amplifier thereby producing distortion of the signal supplied to the load.

Abstract: An audio amplifier including a non-inverting amplifier stage that provides linear amplification without loop feedback for low distortion audio systems. The amplifier stage includes a triode vacuum tube or a triode connected pentode vacuum tube and a P channel field effect transistor (FET). The vacuum tube and the FET are connected in a series combination in which the source of the FET is connected to the cathode of the tube through a suitable resistance. The drain of the FET is connected to a negative voltage and both the gate of the FET and the grid of the tube are at DC ground potential. The input signal to be amplified is fed into the gate of the FET and the output is taken from the plate of the tube which is supplied with a positive voltage through a suitable load. In most applications the grid of the tube is connected to ground, however in some applications the grid may serve as an extra inverting input.

Abstract: A differential amplifying circuit eliminates the common mode component of a composite signal consisting of the common mode component and a differential component. Two differential amplifiers are coupled to a composite signal source so that one amplifier amplifies only the differential component and transfers the common mode component unchanged. The other amplifier processes the common mode component. The outputs of the differential amplifiers are connected to a voltage divider. The output of the circuit is taken from a tap on this voltage divider at a point where the common mode component is eliminated so that only the amplified differential component remains.

Abstract: A bias control circuit for light modulator includes a feedback control loop through which a measure of the modulated laser beam is processed to derive an error correction signal which is superimposed on the normal bias potential to shift the bias point in the same direction as the direction of shift of the operating curve of the light modulator due to the heat generated therein during operation. A feed-forward control loop is also provided to cancel an error signal in the feedback control loop resulting from an intentional gradial variation of the laser beam intensity prior to the modulation so that the average light intensity of the modulated laser beam is correspondingly varied.

Abstract: An expander circuit for expanding stereo signals comprises left and right channel variable gain stages whose gain varies in proportion to the amplitude of the control signals fed to the control inputs thereof; and left and right channel expansion control signal providing means for receiving respectively at least portions of the left and right channel signals and feeding expansion control signals to the control inputs of the variable gain stages. These control signals have amplitudes directly proportional to the amplitudes of the signals fed to the inputs of the expansion control signal providing means. The improvement in the circuit is the addition of a signal coupling network for coupling a portion of the left-right channel stereo image producing signal components to the input of the associated expansion control signal providing means and a much smaller porportion thereof to the expansion control signal providing means associated with the other channel.