VU meter teardown - not what I expected

Discussion in 'General Electronics Chat' started by andrew331, Feb 15, 2016.

  1. andrew331

    Thread Starter New Member

    Apr 28, 2015
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    Hi
    In a box of parts that I will most likely newer use I have some VU meters, old analogue types that used to be very common in audio equipment.
    I decided to have a look inside one.
    What I expected to find was:
    'The original VU meter is a passive electromechanical device, namely a 200 µA DC d'Arsonval movement ammeter fed from a full wave copper-oxide rectifier mounted within the meter case.'
    The meter movement was as expected but no sign of any rectifier!
    Could anyone explain this?
    Andrew
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,546
    1,252
    Not without some photos...
     
  3. andrew331

    Thread Starter New Member

    Apr 28, 2015
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    I damaged the meter taking it apart, so the bits are no in the bin!
    I am thinking it may have needed some external components? Diode?
     
  4. SLK001

    Well-Known Member

    Nov 29, 2011
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    229
    Or, the meter could have been de-linearized using weights around the movement.
     
  5. Nykolas

    Member

    Aug 27, 2013
    87
    31
    VU meters on consumer stereo equipment was sexy, but not Vu. These meters are standard mV movements. A rectifier and a RC network (of varying complexity) would simulate the ballistics of a true VU meter. E
     
  6. RichardO

    Well-Known Member

    May 4, 2013
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    A moving vane meter, maybe?
     
  7. DickCappels

    Moderator

    Aug 21, 2008
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    (Emphasis added by me)


    You stated that the movement was fed by a full wave copper oxide rectifier inside the case . I think you answered your question before you asked it.
     
  8. SLK001

    Well-Known Member

    Nov 29, 2011
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    229
    He stated that this is what he expected to find. He did not find what he expected, so was wondering how a linear movement was made non-linear.
     
  9. DickCappels

    Moderator

    Aug 21, 2008
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    Thank you, I misread the original post and understand, he was talking about the prior meter.

    In that case I endorse Nykolas's explanation in post #5.
     
  10. andrew331

    Thread Starter New Member

    Apr 28, 2015
    14
    0
    Thank you all.
    Nykolas was right, these are not proper VU meters, just regular dc meters that need some external circuitry.
     
  11. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
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    a lot of VU meters on consumer devices use an external rectifyer and rc filter to simulate the non liinear charistics of a coper oxide rectifyer to give a logarithmic scale. your meter just does not have them inside.
     
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