DocumentCode :
1191798
Title :
A Comparatorless Dual-Slope Digital Voltmeter
Author :
Schick, Larry L.
Volume :
17
Issue :
3
fYear :
1968
Firstpage :
186
Lastpage :
192
Abstract :
This paper discusses the design and operation of a digital voltmeter employing a new technique in the analog-to-time converter. The circuit is based on dual-slope integration, which eliminates the necessity of a highly stable clock. Any long term drift in the clock is canceled, so that a simple two-transistor multivibrator clock is used. With the aid of a special diode circuit, the ramp-generating integrator also serves as an accurate comparator, so that no separate comparator is needed for analog-to-digital conversion. Finally, the new circuit requires only a single up counter, and no special polarity switching circuits for automatic polarity indication are needed. The new voltmeter, developed for the University of Arizona´s new Locust Computer, has full-scale ranges of ±1 volt and ±10 volts. Tests on the instruments have shown its accuracy to be ±0.02 percent of half-scale. The sampling rate can be varied from 80 ms to 1 second, and the input impedance is 2 MU on the 10-volt range.
Keywords :
Analog-digital conversion; Circuit testing; Clocks; Counting circuits; Diodes; Impedance; Instruments; Sampling methods; Switching circuits; Voltmeters;
fLanguage :
English
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9456
Type :
jour
DOI :
10.1109/TIM.1968.4313697
Filename :
4313697
Link To Document :
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