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Abstract

This invention relates to a method and circuits for the generation and rapid adjustment of direct current voltages, such method and circuits being used particularly for the adjustment of amplifiers, and amplitude and time gates in ultrasonic test instruments. The voltage to be generated is selected by a selector switch and its value is increased or decreased by means of a set switch. For this purpose, the appropriate contents of storage locations of a read-write memory (RAM) are successively read out of the memory for setting the count of a binary counter. The count may be incremented, decremented or left unchanged according to the position of the set switch and of the selector switch. The binary counter contents are then written back into the appropriate storage location of the memory and converted by a digital-to-analog converter (DAC) to an analog value and stored temporarily by means of a capacitor. The individual locations of the memory are successively and cyclically read out so that a continuously recurring sequence is obtained. During each individual cycle the voltage value can be changed by zero or one digital increment. In an alternative embodiment, the repetition frequency is increased by means of a voltage controlled oscillator (VCO) for reducing the time required to complete each individual cycle.

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First Claim