GB949828A - Improvements in or relating to voltmeters - Google Patents

Abstract

949,828. Analogue-to-digital converters. PHILIPS ELECTRICAL INDUSTRIES Ltd. April 6,1960 [April 9, 1959], No. 12226/60. Heading G4H. [Also in Division H3] In a voltmeter in which the voltage to be measured is compared with a voltage which is varied stepwise, the step voltage is, in turn, compared after a given number of increments, with a constant reference voltage, and a direct voltage is derived from this comparison to adjust the amplitude of the increments so that the step voltage equals the reference voltage after the given number of increments. In the voltmeter described, clock pulses are supplied to a counter T, and through amplifier V 1 to the step voltage generator G which produces 201 voltage increments of about half a volt. The maximum output voltage of generator G is compared with the output of a reference source of 100. 5 volts in block REF. This comparison provides a pulse whose amplitude represents the difference between the two voltages and which is passed through gate P, converted to a direct voltage at Q, and supplied as a constant bias to amplifier V 1 for the following cycle of generator G. The voltage Vin to be measured is compared with the step voltage at Me, a pulse being produced by multivibrator MV as soon as the step voltage exceeds Vin, this pulse being passed through one of gates Pen, which is opened by the concurrent output pulse of counter T, to an output terminal u. The process is repeated for succeeding cycles of generator G. The Specification describes in detail circuits for blocks REF, Me, P, Q and cathode follower KV.