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In search of a meter movement

Discussion in 'Electronic Repair' started by Black Iccy, Oct 29, 2012.

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  1. Black Iccy

    Black Iccy Guest

    Long time since I've posted on Usenet.
    What I want to do is give some public address system
    operators (in a hotel actually), a clear and easy
    visualisation of just how loud they have got things
    running. A VU meter situation.

    What they should be able to do is see, from a distance,
    a meter which preferably will have a 270 degree travel arm

    Small meters just won't cut the mustard. Ideally, too,
    I envisage driving the meter from the amp speaker supply
    so that's why I'm not employing electronic level display systems.
    Trying to keep things as simple as possible.

    It occurs to me that what I really should use is something
    like a car's tachometer movement. I know modern units have
    internal electronics etc. They would be un-necessary and
    unusable so I'd be stripping them out.

    In general, what are the movements?
    Still D'asonval ?
    What sort of FS sensitivity - 1 mA FS?
    Anyone played with these things?
  2. D

    D Guest

    I built an LED VU meter years ago. Like 5 green LED's, followed by 2
    yellow LED's, followed by 3 red LED's, with them lighting sequentially
    with volume level, green to red, fluctuating with the level.
    Theoretically, one of these could be any size you want. I'm sure if you
    do some searching on LED VU meters, you'll find something.

  3. Black Iccy

    Black Iccy Guest

    I hear you Jeff. I know the LM dot/bar chips too.
    All these things require another power supply to
    run them. I'm after something "self-propelled" .

    The ideal situation is to take the 200 W,
    Step it up to 1,000,000 V and use the spearing arc
    to get the barman to turn things down a notch.

    Reverting: Just looking at some E-diagrams for
    these car tacho's, some seem to have a double winding
    as a designate sine/cosine measurement from the chips.
    This implies we are still ultimately at an analog system.
  4. Black Iccy

    Black Iccy Guest

    Oh, as far as a deaf and blind barman can manage. About 10 ft max -)
    It would be within the bar area domain i.e. not for customer viewing.
    Motorised is a slight overkill -) I'm thinking of using the
    Pwr-Amp output suitably rectified and damped.

    Pretty much car dashboard size will be OK. Perhaps no more than 3" dia.
    They can occasionally wander over to inspect the audio level after being
    beaten by a whip (if they ever cared enough)

    No, no, no. Its a pub not a disco. -)
  5. Black Iccy

    Black Iccy Guest

    Yep. There are kits out there and I could do the same.
    Two (three ?) things working against that.

    1. Keeping a constant E/I supply to the displaying/sensing device
    which would probably be needed at low power levels. Easy to drain
    a watt or less at hi-levels (max 200 power amp)
    2. Lights get 'missed' in a well lit area.
    3. Cost. They won't come at things that cost money (gee. surprise).
  6. N_Cook

    N_Cook Guest

  7. N_Cook

    N_Cook Guest

    When the team hits on a device , my pub could do with one. Amp and controls
    in a sideroom with not even a monitor speaker in that room. Why is it beyond
    management to put stickers on the volume control scale with numbers of
    people in the bar comensurate with speaker audio levels and not the usual
    meaningless 0 to 10 numbers.
  8. Jamie

    Jamie Guest

    step up transformer of some kind?

  9. mike

    mike Guest

    That's an extremely BAD suggestion.
    First thing that's gonna happen is that the lawyers will descend on
    him with injury lawsuits and he'll be out of a bar.

    Claim it's a
  10. hr(bob)

    hr(bob) Guest

  11. Black Iccy

    Black Iccy Guest

    Already got that facility. It's called thermal overload protection system.
    It works too. Amazing the panic it causes when there's silence and they find
    they don't uderstand the problem and where it lies -)
  12. Black Iccy

    Black Iccy Guest

  13. Black Iccy

    Black Iccy Guest

    <Snaps fingers>. That's it. Sheer genius!
    A single 2" loudspeaker clamped to the back of a barometer.
    Speaker cone has a pressure valve fitted.
  14. josephkk

    josephkk Guest

    Hmmm. Off the top, an ordinary (wide pointer?) meter with a video cam
    hooked up to a 17 inch monitor. I doubt that the hotel staff would
    recognize proper VU ballistics.

  15. Black Iccy

    Black Iccy Guest

    Kinda attractive but it would make my Cherry-brandy,
    at the bar, a little black looking wouldn't it?
    I wonder where GreenXenon got to -)
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