Sundstrand Data Control, Inc.

Henry J Lukes

Walter Kamphorst

Romeal F Asmar

Gain peaking and attenuation of audio signals above the peak gain frequency are provided in an audio frequency equalization preamplifier that includes an operational amplifier having a feedback network including first and second resistors and a feedback capacitor connected between the output and the second feedback resistor. Two or three low pass RC filter sections are connected between the audio signal source and the noninverting input of the operational amplifier with a circuit connecting a capacitor of the second RC section from the noninverting input to a node between the second feedback resistor and the feedback capacitor.

Equalization preamplifier with high frequency gain peaking

A reel-to-reel constant speed tape transducer in which the torques of the reel motors are controlled to maintain the tension in the tape to the take-up reel substantially equal to or slightly greater than the tension in the tape from the supply reel. The speed of the take-up reel provides a measure of reel diameter to generate signals which control the torque of the reel motors.

Tape tension control for a tape transducer

A charge amplifier having minimum offset voltage such as for use in processing a signal from a capacitive transducer. The amplifier is arranged to minimize the offset voltage and drift. The amplifier is arranged to be reset to zero upon application of supply voltage thereto, and the resetting circuit is arranged to reset the amplifier automatically during an adjustable interval after application of the supply voltage. The charge amplifier is further compensated for temperature variation and is arranged at minimum offset voltage notwithstanding strong background noise.The amplifier is arranged to have a drift of no more than a fraction of a millivolt per second. The amplifier circuit includes an improved switching arrangement and may utilize a second amplifier circuit for effecting temperature compensation.

Charge amplifier with minimum offset voltage

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.

Differential amplifying system

Direct readings of the timing angle and duration of the fuel injection of a diesel engine along with the engine speed are provided by an electronic test instrument that converts the duration of the timing advance and the duration of one engine revolution into electrical pulses of corresponding width. Both these pulse widths are then converted to corresponding electrical quantities and the quantity which corresponds to the timing angle is divided by the quantity which corresponds to one engine revolution to produce an indication of timing angle, or alternatively a constant reference quantity is divided by the quantity which corresponds to the engine revolution, thus providing an indication the engine speed.

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Bellevue, WA, United States of America

Henry J Lukes