EIGHT_CHANNEL_COMPUTERIZED_3SUP1_SUP__SUB2_SUB_DIGIT_VM

Published:2009/7/15 4:04:00 Author:Jessie | From:SeekIC

Displays up to eight different DC voltages on CRT terminal of microprocessor under key-board control, using BASIC commands and BASIC routine given in article. Uses Motorola MC14433 modified dual-lamp integrating analog-to-digital converter. Unknown voltage is applied to integrator having defined integration time constant for predetermined time limit, to give output voltage proportional to unknown voltage. Computer program substitutes -2,000 V reference from IC2, and circuit keeps track of time for integrator output to move back toward zero. Changing reference to 0.200 V makes same 1999 count represent 199.9 mV full scale. IC1 performs about 25 conversions per second. IC3 and IC4 are output buffers, IC5 is 7474 used as set-reset flip-flop. IC6 is eight-input CMOS multiplexer input.-S. Ciarcia, Try an 8 Channel DVM Cocktail!, BYTE, Dec. 1977, p 76, 78, 80, 92, 94, 96, and 98-103.



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