Multimeter_single_chip

Published:2009/7/19 21:49:00 Author:Jessie | From:SeekIC

This circuit shows an ICL7149 that is connected as a low-power, autoranging digital multimeter. Although the ohms ranges do not need protection, the current ranges should be provided with fast-blow fuses between 55A and the 0.1- and 9.9-Ω shunt resistors. Also, the 10-kΩ resistor at pin 7 must be able to dissipate 1.2 or 4.8 W for short periods during accidental application of 110- or 220-V line voltages, respectively. The suggested crystal is a Statek CX-1V, the display is an LXD part number 38D8R02H, and the beeper is a muRata PKM24-4A0.



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