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EL Wire Project for 50cc Scooter

Discussion in 'General Electronics Discussion' started by jcan, Oct 10, 2013.

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  1. jcan

    jcan

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    Oct 10, 2013
    Hey guys.

    I am working on installing some EL wire on my scooter. I'm going to try and figure out how to wire it to the bike's power.

    I'll post updates as I go. Right now I'm messing around with the placement. I've stuck it to the edge of one of the body panels and it runs all the way around to the other side.

    If anyone has some advice to give on running this 3v wire from the battery, I would be very happy to hear it.

    Thanks for your interest!
    Attached an image to explain the project a bit:

    [​IMG]
     
  2. BobK

    BobK

    7,682
    1,689
    Jan 5, 2010
    EL wires runs on about 100V AC, not 3V DC. The original power supply uses an inverter to produce the 100V AC from the 3V batteries. Your best bet is to find and EL power supply that runs from 12V. They should exist.

    Bob
     
  3. jcan

    jcan

    4
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    Oct 10, 2013
    Thanks for the tip. I was just reading up on EL wire and was surprised that it runs off AC. I can probably find the right inverter, but I don't want to buy something that is already put together. I have some LM317's laying around..

    Could I set up something with the 317, like this:
    [​IMG]
    ...Then feed that into the 3v inverter I already have?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    You need to set the 317 up as a voltage regulator, not a current regulator. And then you need to set it up for an output of 3V.

    If the current required is fairly low, you may not need a heatsink.
     
  5. jcan

    jcan

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    Oct 10, 2013
    I found this design on the wikipedia page for LM317:

    "typical configuration, including decoupling capacitors"
    [​IMG]

    How can I figure out which rating of resistors to use?
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,505
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    Jan 21, 2010
    The specs for the 317 will tell you that R1 needs to be about 220 ohms and it will have 1.25 volts across it. The power dissipated will be 1.25*1.25/220 = 0.007W. You can use the smallest cheapest resistor you can find :) A 1/8W resistor would be fine.

    R2 will drop 3V - 1.25V - 1.75V. Ignoring the math needed to calculate it, rest assured that it is about 308 ohms. I'd use 330 ohms.

    Your output voltage will be about 3.125V, but could vary by about 5% or so either way.

    With less than 2V across the 330 ohm resistor, the power dissipated will be less than 0.012W, so an 1/8W (0.125W) resistor is again heaps large enough.

    There are some other considerations, but knowing the current required would be a huge help.

    If the load draws 100mA, then at 3V, it is consuming 0.3W, Because of the way a 317 operates, it is dissipating approximately 3 times this power (12-3)/3. So the regulator will dissipate 0.9W. This might be OK, but a small heatsink would be good.

    A teatsink is connected to the tab and the tab is connected to the output, so beware you don't short anything out. Special mountinh hardware is made to ensure that the 317 is electrically isolated from a heatsink. Note that if you use a metal bolt you also need to have special insulating washers
     
  7. jcan

    jcan

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    Oct 10, 2013
    Last edited: Oct 11, 2013
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