Voltmeter display module Problem

Discussion in 'General Electronics Chat' started by ISB123, Sep 2, 2014.

  1. ISB123

    Thread Starter Well-Known Member

    May 21, 2014
    1,239
    527
    Hello,I bought one of these Voltmeter modules for my power supply project since they are handy and I didn't want to mess with making one myself.

    Here is the issue.

    I bought 10k 5% resistor since I couldn't get 1% one but that shouldn't have any impact on operation of voltmeter but only on measuring accuracy. First I soldered RA 10K R and RB 10M T but since I accidentally got it soldered the other way around so it was RA 10M and RB 10K. So for first test i took 1.5V battery and measured it. The result was 63.4Vo_O.So that's when i noticed that I soldered resistors the other way around and I though that must be the reason so this time i soldered them right,then I turned the display on and its only reading -0.00V or 0.00V if i put my finger on RB(10K resistor) it will read 0.07V or so.I tried adjusting the trimpot which had no effect.
    What could be the issue?

    Here is the datasheet on french:http://www.produktinfo.conrad.com/datenblaetter/50000-74999/063043-an-03-fr-T_afficheur.pdf
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    I cant read french. Some of these little DC meter modules cannot have a common connection between the negative side of the signal being measured and the negative of the battery supply. Read the data sheet yourself, looking specifically for that issue...
     
  3. ISB123

    Thread Starter Well-Known Member

    May 21, 2014
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    527
    OK,it seems to be fixed now after unplugging few times its reading correctly or at least its reading something.I really hate those fixed decimal points.
    One battery is showing 0.17(which I think is 1.7V) some are showing 0.09V(used ones)so i guess its reading correctly.
     
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