GB1192734A - Analogue to Digital Converter - Google Patents

Abstract

1,192,734. A/D converters. SCIENTIFIC SYSTEMS Ltd. 27 Dec., 1967 [1 Oct., 1966], No. 41065/66. Heading G4H. An analogue digital converter includes a stepping switch SS1 (Fig. 2) which as it is stepped feeds a staircase voltage signal on conductor 13 (Fig. 1) to a comparator 12 for comparison with an input voltage on conductor 11, an output pulse being transmitted to, for example, automatic dialling equipment or an indicator for each step at which the staircase signal is less than the input signal. In the embodiment described the stepping switch SS1 (Fig. 2) is connected across resistors 22 and a further stepping switch SS2, connected across the same resistors, follows the first switch until the voltage on conductor 13 is greater than that on conductor 11, the second stepping switch SS2 then remaining on the next lower step. A further stepping switch SS3 across resistors 23 connected between conductors 13 14 is then stepped, pulses being transmitted for each step by a tone generator 33 until the voltage on conductor 15 exceeds the voltage on conductor 11. The two series of pulse trains, each representing one decade of the digitized signal, are preferably audio pulses of two different frequencies but different amplitude or duration pulses may be used for the different decades. The apparatus may be used for measuring liquid level, the potential on conductor 11 being taken from a potentiometer 10.