Abstract: A high fidelity audio amplifier having a pair of cooperating active amplifying devices includes two diodes, each of which is connected in a distinct signal pathway directly associated with an active amplifying device so that the amplifier achieves true Class A operation over the full range of normal input signals. The amplifier can achieve true Class A operation using bipolar transistors, field effect transistors, or vacuum tubes as the active amplifying devices.

Abstract: First and second transistors are connected in long-tailed-pair amplifier configuration, with interconnected emitter electrodes connected to a constant current generator that supplies the tail current. Input signals applied to the base electrodes of these transistors are pre-distorted by diodes connecting the base electrodes of the first and second transistors to a common node point. These diodes are provided forward bias currents from constant current generators, so they float with regard to common-mode components of the input signals and do not impair the common-mode signal rejection of the long-tailed-pair amplifier configuration.

Abstract: A temperature stable displacement sensor with fine resolution having a housing with a radiation source, preferably an LED for generating radiation in the near-infrared region, a lens for collimating the LED radiation into a beam spaced along the axis of the housing from the LED by a distance equal to the focal length of the lens, a reflector for intercepting and reflecting the beam, the reflector comprising a first fluid having a relatively high reflection coefficient and a second fluid supported by the first having a substantially greater viscosity than the first fluid, and a radiation detector located adjacent the radiation source for receiving the reflected beam and generating an electrical signal representative of the angular position of the reflected radiation beam incident thereto with respect to a reference axis.

Abstract: A three-axis stellar sensor comprising a conventional stellar sensor for detecting the presence of light from a radiant body. The stellar sensor is mounted on a stable member located in a vehicle. The axis of the telescope of the sensor is parallel to a first line of sight to a first radiant body and a silvered mirror located at an angle of 45.degree. to the axis of the telescope provides a means to measure light from a second radiant body along a second line of sight 90.degree. displaced from the first line of sight. Additional means are provided to rotate and measure the mirror angle.

Abstract: An amplifier circuit having an input adapted to receive a signal to be amplified from a signal source, at least two sets of combined amplifying transistors and associated power sources for the amplifying transistors, the two sets constituting first and second amplifying stages, a switching transistor for automatically switching the amplifying operation of the amplifier circuit from the first amplifying stage to the second amplifying stage depending upon the amplitude of the input signal to the amplifier and a load to which the amplifying transistors are connected in parallel.

Abstract: A circuit for preventing latch up of a differential-input stage, which includes both bipolar and field-effect transistors, without degrading performance including means for clamping the base electrode of the slave transistor of a current mirror whenever the potential thereacross approaches a level sufficient to forward bias the base collector junction thereof to forestall its reaching such level.

Abstract: An electronic reverberation device comprising an input amplifier and an output amplifier connected in a circuit in which a delay device is connected between an output of the input amplifier and an input of the output amplifier, and a feedback path connects an output of the output amplifier to an input of the input amplifier. In order to render the operation of the device substantially frequency-independent, the delay line is a variable delay line the delay of which can be regulated by a regulator controlled by a control device which derives a control voltage from the output of the input amplifier. Preferably, the delay device is a bucket memory, the regulator a clock, and the control device comprises a diode having one terminal connected to the output of the input amplifier and another that is earth-connected through a capacitor and connected through a resistor to a control input of the clock.

Abstract: A power transistor in the final stage of an IC amplifier feeding a reactive load, such as a loudspeaker, has an emitter resistor connected across the input of a monitoring transistor by way of a diode, the monitoring transistor being part of a protective circuit which reduces the input signal to the power amplifier in the event of an overload. To retard the response of the protective circuit, for the purpose of preventing signal distortions in the event of brief power surges, the diode and the monitoring transistor are so disposed on the silicon chip of the amplifier that a thermal wave from the overheating power transistor will first strike the diode, thereby reducing its resistance to compensate for an increased voltage drop across the emitter resistor, and will reach the monitoring transistor with a certain delay; if the overload persists, the resulting increase in the conductivity of the monitoring transistor re-establishes the full sensitivity of the protective circuit.

Abstract: The amplifier is intended for use in situations where a considerable distance separates the instrument (for example a piezo-electric transducer) to be monitored and the control room. The amplifier comprises a charge/current converter for converting the charge output of the instrument into a current signal, the charge/current converter being connected to operate as a high impedance current source, a current/voltage converter and a connecting cable connecting the current output of the charge current converter to the input of the current/voltage converter.

Abstract: An active filter is disclosed for providing improved notch and band pass filters. The output to input frequency response of an active filter is mathematically expressed as a ratio of two polynominals in the Laplace operator S. In any notch filter, the coefficient of the S term in the numerator must be reduced to zero, while in any band pass arrangement the coefficient of the S term in the denominator is reduced to zero. The improved notch filter provides an input circuit for the operational amplifier portion of the filter which eliminates the S term in the numerator so that adjustments to reduce this term are unnecessary. Similarly, in the improved band pass filter, the S term in the denominator is eliminated in the feedback circuit provided for the operational amplifier, so that adjustment is unnecessary to eliminate the coefficient of S.

Abstract: An optical level detection probe is disclosed having first and second spaced apart optic guides, each guide having a 45.degree. angle reflecting face or surface opposing one another such that light traveling along the first optic guide will reflect off of its 45.degree. angle face, reflect off of the 45.degree. angle face of the second optic guide, and travel along the second optic guide for detection by a sensor as long as the material is below the reflecting surfaces. When the material reaches the reflecting surfaces, the light will be blocked.

Abstract: A light activated acoustic pinger that is useful for underwater three dimional homing. The pinger includes a spherical lens system, a tone burst generator electronics system and a high pressure water tight encasement. When a light source used by an underwater diver, submersible, underwater television system or navigator is panned on the pinger lens system in either the X or Y planes the ping rate will vary depending upon the incident angle of the light received by the spherical lens. In addition, moving the light toward the pinger in the Z direction will increase the ping rate. From the ping rate and the movement of the light source in the X, Y and Z directions an underwater navigator can determine the direction of the pinger and target. There is no battery drain until the pinger is activated by light and therefore targets that have been lost for several years may still be found based on battery shelf life.

Abstract: An automatic gain control circuit is provided with a constant potential circuit point, an amplifier circuit of which the input terminal is connected to the constant potential circuit via a resistor, and a feedback circuit which is connected between the output terminal of the amplifier circuit and the constant potential circuit point and the gain is controlled in accordance with the input voltage. The feedback circuit includes a first transistor whose base is connected to the output terminal of the amplifier circuit, the emitter is connected to a DC power source terminal and a second transistor which has a base connected to the collector of the first transistor and an emitter-collector path connected across the resistor.

Abstract: A discrimination circuit operable to discriminate between an input signal in the form of a pedestal and disturbance signals superimposed thereon has an A-D converter to digitize a disturbance-free reference pedestal signal, circulating shift register to store the digitized reference signal, a D-A converter to produce a pedestal signal from the reference signal, a controlling clock to shift the reference signal in the store in synchronism with the incoming signal such that the two pedestal signals are available together, and a comparator to compare the reference signal with the input signal to produce an output caused by differences due to disturbances. The circuit forms part of an optical surface inspection apparatus.

Abstract: An amplifier for use as on the output buffer for semiconductor memories including a fusible element added to a push-pull configuration to allow permanent conversion to an open collector configuration by blowing the fusible element or including a semiconductor element added to a push-pull configuration to cause it to have an open collector configuration and being permanently converted to a push-pull configuration by shorting the semiconductor element.

Abstract: This invention provides a method and means for amplifying signal waves with high efficiency that comprises signal sampling means operating at the Nyquist rate or greater, sample-quantizing means, a plurality of circuits that link the quantizing means to a plurality of controlled current-switching means, combining means that combines the outputs of the plurality of switching means, and filter means that reconstructs an amplified facsimile of the signal.

Abstract: In a multi-stage amplifier with delayed AGC-control gain control in one stage is effected by means of controllable current distribution between control transistors. The take-over point of the delayed AGC for a previous stage is determined from the ratio between the direct currents of said control transistors.

Abstract: The present invention comprises a circuit for addition to a non-linear amplifier wherein the non-linearity is of the first degree. The circuit essentially adds a signal (or signal variable impedance path) to that already existing to remove non-linearity in operating characteristics over a given range of voltage.

Abstract: A nonlinearly variable gain circuit is utilized to produce an inverted logarithmic S curve of gain versus potentiometer rotation while using a linear resistance taper potentiometer. An operational amplifier feedback circuit uses the linear potentiometer and a resistance network in combination.

Abstract: An amplifier transistor has its base-to-collector voltage maintained substantially zero, and its collector-base junction has in inverse-parallel connection therewith an auxiliary semiconductor junction exposed to the same transient ionizing radiation environment. Photo-currents generated in the collector-base junction of the amplifier transistor responsive to transient ionizing radiation are counteracted by the photo-currents concurrently generated in the auxiliary semiconductor junction, so amplification can continue without being unduly hampered by such radiation.