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How can I induce a current?

  1. May 19, 2014 #1
    Hello,
    I was wondering how I can induce a current to power an led? I tried using two 100 uH inductors but they did not work. I was using an AC current from a car inverter.
    Thank you.
     
  2. jcsd
  3. May 19, 2014 #2

    Simon Bridge

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  4. May 19, 2014 #3
    I lay the inductors on a desk and place the tips close together. I then used the inverters for cars that allows you to plug a house socket into your car. I connected 12 volts worth of AA batteries to it. It is a 140 watt inverter and I connected it to an inductor. Then I placed the tip of that inductor in front of the tip of another inductor. I connected an LED directly to the second inductor and it did not light up. I then tried connecting an LED to the inverter with a resistor (to test if the inverter was working). It lit up and flashed quickly and the resistor blew. I used these inductors.

    http://www.ebay.com/itm/321289626041?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

    Could it be possible that these inductors are not meant for the task I am trying to do?
     
  5. May 19, 2014 #4

    davenn

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    firstly....
    What you did was very unsafe. It could have resulted in a significant bang or worse ....
    An injury to you or others
    I don't know where you are from so I don't know if the output of your inverter was 110 or 220VAC


    PLEASE DONT DO THAT AGAIN


    If you are going to experiment with any voltage AC or DC use low level voltages, preferably less than 30V till you have lots of experience and understand what you are doing

    You really should find a local mentor that can give you hands on guidance :smile:

    Secondly....
    LED's don't work directly from an AC voltage without a few other components

    For a simple and safe induced current experiment
    Do you have a bar magnet?
    Do you have a multimeter ?

    a magnet moving near a coil will generate a small voltage and current

    Dave
     
  6. May 19, 2014 #5

    Simon Bridge

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    That would be an understatement. Yes. Pretty much the same for the inverter.
     
  7. May 19, 2014 #6

    jim hardy

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  8. May 19, 2014 #7
    I know 140 watts is a lot. That is why I did not connect the inverter to a car battery or house socket. I also didn't think that 10 1.2 volt AA batteries could produce 140 watts. The inverter also has a fuse, so I thought it would blow before it hurt anyone (it did not). So I assumed that the inverter would put out 110 volts with a much lower current (I was still worried about using such a high voltage because I have never used it before). Before I tried using 10 AA batteries, I tried 3 3.7 volt Button cell batteries. But they are weak and the LED light would flash on and a few seconds later it would turn off and repeat. I thought this was because the button cell batteries could not provide enough current to power the inverter. And the LED did light from the AC current connected directly (I assumed it would since it is a diode). Even when I connected the LED to the inverter with 10 AA batteries and resistor, it still lit up but the 1K resistor blew (The LED is still okay).

    So is there any other component that induces a current (other than an inductor)? As for the AC current, I was thinking of taking an AC motor from a broken coffee grinder or blender and connecting that to a DC motor. I used the inverter now because I have not yet found an AC motor.

    What do cell phones use to charge inductively?
    Thanks all for your help.
     
  9. May 19, 2014 #8

    sophiecentaur

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    I have to point out that a fuse doesn't provide any protection at all against electric shock! People can die with a very few mA and the value of fuse you are likely to have will be 1A or more (5A, 13A, 30A, 60A etc.). Also, fuses take a long while to blow (biologically speaking).
    The purpose of a fuse is to prevent too much current flowing through a wire or component. It protects equipment not people - directly.

    The amount of energy you can get out of a humble AA cell is more than enough to kill you, if you use it in an appropriate circuit. The only way to be sure (unless you knowalot!!) is to stick to 12V circuits or lower.
     
  10. May 19, 2014 #9

    davenn

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    how about sticking with the simple and safe ideas that Jim and I gave you
    till you understand a lot more about what you are doing...
    ie. learn to walk in electronics before you try and run :smile:

    you also didn't answer my questions :wink:

    cheers
    Dave
     
  11. May 19, 2014 #10
    I don't have a bar magnet or multimeter. But I have magnetic wire and a voltmeter. I also bought a flashlight from the 99 cent store that I can crank to charge. When I took it apart, I found a coil and weak round magnet. It charges with DC since the magnet only moves in one direction and the coil is connected directly to 3 button cell batteries. I guess if I kept rotating the magnet one direction and then the other it might generate an AC.
     
  12. May 20, 2014 #11

    sophiecentaur

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    What is a "magnetic wire"?
    What makes you think that the flashlight works on DC? What would be the point of rectifying what the internal generator is giving you? Could you explain what makes you thing the output is DC? (If it did, the same principle would be used all over the place!)
    Like Dave said: get a few basics sorted out first.
     
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