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High powered bright led light

Discussion in 'LEDs and Optoelectronics' started by machete101, Sep 28, 2011.

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  1. machete101

    machete101

    5
    0
    Sep 28, 2011
    Hello, I am new to this site.

    I looking to get in to building electronic circuits, i have previous experience but not a massive amount.

    For my first project im looking to make something to go on my off road pit bike, and i am looking to make a bright head light, and i thought led would be best option, as i has seen you can get the high powered led and use a few components as a alternative to the expensive drivers to power them. Can someone help me to construct a circuit that would be a cheap and suitable head light, as i not sure what components i need an how to go about it etc

    thanks
     
  2. davelectronic

    davelectronic

    1,087
    12
    Dec 13, 2010
    Pit bike lamp

    Hello machete101.
    Its not all that hard to do, build an led array, ive seen cars converted over to full led for all lamps, there are projects out there, find the design and brightness you want, couple that with the led array's power requirements, resistors / series / etc, then build it, don't know where you are in the world, i am in the uk, there was some good projects in the magazine, EPE every day practical electronics, if your in the uk i will dig it out and send it to you, if i can find it, think i know where it is, or build your own design.
    Dave. :)
    PS, just let me know in a PM if you want the EPE copy.
    Posting emails is not allowed.
     
  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,387
    2,772
    Jan 21, 2010
    I have seen a number of *bright* bike headlights that are cooled by airflow. They get realy hot if you use them at full brightness whilst stopped.

    Heat kills LEDs and whilst a couple of watts may not seem like a lot of heat, unlike a light bulb, relatively little is in the beam of light, so the housing has to do a lot more heatsinking.
     
  4. machete101

    machete101

    5
    0
    Sep 28, 2011
    hi , thanks for the replies

    im just wondering is it possible just to use resistors with a high powered led or should i make/buy a driver.

    I have see u can make a driver with a transistor ,a regulator and 2 resistor, but i dnt know wat resistor i need to use. Can anyone help as i want to build a fairly small but bright torch and i dnt think normal 5mm leds are gunna give me enough light.


    thanks
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,387
    2,772
    Jan 21, 2010
    Read this and come back with any questions you still have.
     
  6. machete101

    machete101

    5
    0
    Sep 28, 2011
    Hi
    thanks for the replies

    I kinda understand a bit more now, but if i was to use the LM317 regulator and a resistor, i dont no what resistor to use, i have tried the calculator on the link given ( the current regulator one) this is the right one isnt it? but i dnt understand what reading i need and how to use it etc,

    thanks
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,387
    2,772
    Jan 21, 2010
    Here is the circuit diagtam:

    [​IMG]

    And here is the link to the calculator for the resistor value. (Use the current regulator one which shows an equivalent schematic to the one above)

    Now, what don't you understand?
     
  8. machete101

    machete101

    5
    0
    Sep 28, 2011
    i think i got it now the led i gunna use has the spec

    Luminous intensity max.
    typ.117lm (max.:228lm)
    Viewing angle
    90°
    Color Temperature
    5700-7000K
    Forward Voltage
    typ. 3.3V (max.3.7V)
    Recom. forward current
    typ. 350mA (max.1000mA)


    so i need a 3.5 or 3.6 ohm resistor in that lm317 current regulator circuit, what voltage do u recommend i use with it led. Also how would i go about making a brightness control, would i just need a variable resistor.

    Sorry for asking a load of question im just getting in to electronic and wanna make sure i get the right components and have it all plan before i start.

    thanks
     
  9. TBennettcc

    TBennettcc

    292
    2
    Dec 4, 2010
    3 2700mAh AA batteries in series will give you about 7 hours of runtime per 3 batteries. You will need a 3.9 ohm resistor capable of dissipating at least a half watt, along with your LM317, in the configuration provided by Steve above.

    If you want to use a variable resistor, you will have to add it in the circuit, in addition to the resistor already there. If you don't, and turn the pot all the way to zero, you will cook the LED. This pot from RadioShack should fit the bill:

    http://www.radioshack.com/product/index.jsp?productId=2062299
     
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