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power indicator

Discussion in 'General Electronics Discussion' started by gaz6660, Oct 24, 2011.

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  1. gaz6660

    gaz6660

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    Oct 24, 2011
    hi guys - completely new here and not sure you'll be able to help. Am stuck with a problem and need some guidance.

    basically, what I want to achieve is some form of led indicator to show there is power in a junction box. basically the situation for example is this: one box, with one incoming and one outgoing cable. 3 terminals in the box. I don't want to take anything other than the incoming and outgoing cables to the terminals. I'm looking for something that works like a voltage detector pen - something that can show when there is voltage in the box. I don't want it to draw power - preferring it to run off induction or something similar.

    Am in no way an electrician - this is more a "prove someone wrong" question. It's something that has been bugging me for ages now.

    where do I start? Can it be done?

    Really appreciate any help


    Gareth
     
  2. OLIVE2222

    OLIVE2222

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    Oct 2, 2011
  3. duke37

    duke37

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    Jan 9, 2011
    You can't get energy out (light) with no power in.

    Why not connect to the terminals?
    Why use a led?
    The way I would do it is to connect a neon indicator which can be obtained with a built-in resistor or can use an external resistance. This is the type of indicator in a magic screwdriver.
     
  4. gaz6660

    gaz6660

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    Oct 24, 2011
  5. Resqueline

    Resqueline

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    Jul 31, 2009
    Those are meant for what we would refer to as high-voltage systems, ranging from 3 kV to 36 kV. Quoting from the documents:
    "VisiVolt™ indicator is a completely passive device (powered by the electric field surrounding the energized conductor, on which it is installed) and is entirely maintenance free."
    Previously one seems to have used neon indicators for the same purpose, working in pretty much the same way (capacitive currents due to the electric field).
    Low voltage systems like those at home don't produce sufficient field currents to run passive devices like this, but a battery driven device can detect the presence.
     
  6. daddles

    daddles

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    Jun 10, 2011
    You don't say what power this is; it sounds like a line voltage situation, but if not, please clarify. If it is a line voltage situation, one of the simplest solutions (but you do have to connect it into the circuit) is to just connect in a neon indicator bulb and a resistor. The parts cost will either be free from scrounging or perhaps a dollar or two if you buy retail. An LED can also be used, but there are more parts necessary to help protect the LED from the higher line voltages.
     
  7. jackorocko

    jackorocko

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    Apr 4, 2010
    I don't really care about the voltage detector circuit(others have addressed that), but what is this "prove someone wrong" thing you are going for? This intrigues me... why would you need to prove there is line voltage going through a junction box? AFAIK, unless you switch off the breaker, there should be line voltage 24/7.
     
    Last edited: Oct 24, 2011
  8. OLIVE2222

    OLIVE2222

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    Oct 2, 2011
    maybe it's for temporary installation. When you works for events the scene can be like a hive and you don't know always who is doing what. Sometimes the breakers are far away or in another building, so having a main presence indicator can be useful.
     
  9. gaz6660

    gaz6660

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    Oct 24, 2011
    ah, the "prove someone wrong" is a work thing - our development guy says it cant be done easily. i want to show it can (but am in sales, not technical)

    We do deal with various voltages, many much lower than 3kV, though to be honest, if I could get it to work in any configuration, victory would be mine. To explain a little further, we work in hazardous oil and gas industries and so there are rules to adhere to - hence why its not possible to terminate more than one core per terminal.

    Thanks for the responses guys
     
  10. gaz6660

    gaz6660

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    Oct 24, 2011
    and Olive2222, its exactly that, but rather than events, it may be an oil rig!
     
  11. jackorocko

    jackorocko

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    Apr 4, 2010
    what does that mean exactly? In other words you can not have more terminals then the 3, one per each pair of wires? I think resqueline has hit it on the head then. Battery operated device
     
    Last edited: Oct 27, 2011
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