Vu meter

Discussion in 'General Electronics Chat' started by frenchie29, Mar 24, 2009.

  1. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    I bought a Vu meter just to experiment now I'd like to know how can I wire it. I can test it with a little sound board that I have at home I would assume that pin 2&3 of the xlr coming out of the board would go on one of those solder blob that's on the picture and pin 1 to the other side. Is that make sense?

    [​IMG]

    [​IMG]
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    If you have a meter, put it on the ohms scale and touch the leads to those solder blobs. The correct contacts should not only read a resistance with the meter, but cause the meter movement to jump a bit.

    Why didn't the meters come with a hookup diagram?
     
  3. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    I found the polarity of the meter. I tested it with my multimeter and it reads the ohms that's pretty cool, but how can I wire it to an xlr cable to monitor what is coming out of my mixing board. I bought that meter for $5 it was in a bin with no instruction.
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    You have asked the question also on another forum.
    http://www.dutchforce.com/~eforum/index.php?showtopic=25334

    If you want to know the "real" polarity, take a AA battery (you know the knob is positive) with a resitor of 10 K in series.
    Then do the test like with the meter in resistance measurement.
    Then you know also the polarity of the meter.

    Greetings,
    Bertus
     
  5. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    When I wire it to the output of the mixer I can hear the sound coming out of the meter (I know that's pretty weird), but the needle won't move. Does it need voltage with the audio signal?
     
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I think that the audio signal is so fast and going positive AND negative that the needle hardly moves.
    I think you need to rectify the signal from the audio input to have it going one side.

    Take a look at this page how a analog VU meter is connected to the rectifying part.
    http://sound.westhost.com/project55.htm

    Greetings,
    Bertus
     
  7. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    That's a bit more complicated then I taught.
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Are there no more components on the PCB ?
    I only see the back of the PCB. It has some more solder joints.
    Is it possible to make a picture of the front without the gray plastic housing ?

    Greetings,
    Bertus
     
  9. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    0
    ok I finally see some movement proportionate to the reading of my mixing board but not the right db value I'm outputting +8db from the board and read -7 on the Vu meter. The vu meter won't move below +6db from the board.
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What is behind the three pin connections ? (red circle).

    [​IMG]

    Are there potmeters to adjust the sensitivity ?
    Can you also make a sharp picture of the centre part ?

    Greetings,
    Bertus
     
    Last edited: Mar 24, 2009
  11. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    It's sealed pretty tight

    there's 2 resitors a 3 pin connector, a trimpot on each side to calibrate.

    [​IMG]


    [​IMG]
     
  12. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    Trimpots for calibrating I'm taking pix with my iphone and can't find the focus on it that's why all pix a blurry. I'll try with a "real" camera the 3solder joints you see in the middle is for a 3 pin connector same type as in a computer hard drive but smaller.
     
  13. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I think the input must be the white part (with three pins) in the middle.
    The middle pin will be ground the other two left and right.
    The trimpots are to adjust the sensisivity.

    Greetings,
    Bertus
     
  14. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    Where do I connect the ground to?
     
  15. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    I think you need to connect it like in the picture.

    [​IMG]

    I have written signal 1 and 2 becouse I can not read the text on the PCB.

    Greetings,
    Bertus
     
  16. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    I tried it I get the same results as hooking it up to the solder blobs.

    So I assume that one blob represent audio input and the other one the ground. There's something that I need in between to boost the signal.
     
  17. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Can you post a picture with circles round the blobs you mean ?
    Did you salredy use the connections I pointed out ?
    Did you also change the settings of the trimpots ?
    This should change the sensitivity.

    Greetings,
    Bertus
     
    Last edited: Mar 24, 2009
  18. frenchie29

    Thread Starter Active Member

    Nov 28, 2008
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    It helps but I can heard the music going trough the meter and still not accurate at all in the db range.
     
  19. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Is the meter giving a to low reading ?
    If so you need to amplify the signal.

    Greetings,
    Bertus
     
  20. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    Hi Frenchie:

    If this is a true broadcast VU meter, and not just a consumer copy, it will be a true rms AC meter. The ballistics of VU meters are carefully defined as well...that is the acceleration and damping. They are designed to read milliwatts across a 600 ohm resistive load.

    The best way to test these is with a signal generator, not a DC ohmmeter.


    eric
     
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