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Help with a low resistance meter

Discussion in 'General Electronics Discussion' started by mevrocket, Jun 7, 2012.

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  1. mevrocket

    mevrocket

    1
    0
    Jun 7, 2012
    Hi all
    new to the forum and not the best with electronic.. altho im not to bad at soldering and deciphering diagrams.. i just have no idea with the techie side of things.

    id like some help if possible from one of the Electronic wizards here..

    id like to make a simple circuit that will light up an led when the resistance in the circuit falls below a 100 ohms. or a circuit that i can adjust the resistance that triggers the LED

    the circuit will be powered by a 12 volt car battery

    thanks
    Paul
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,644
    2,691
    Nov 17, 2011
    You want a continuity tester with a treshold of 100 Ohm.

    Look here: http://www.extremecircuits.net/2010/04/continuity-tester-circuit-diagram.html
    This circuit probably works from 12 V, too.
    I don't think the type of OpAmp is very critical. If you want to / have to use another OpAmp, just make sure it operates from a 12 V (9V) single supply. The threshold for continuity/discontinuity detection should be adjustable by the potentiometer.

    Harald
     
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