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How to lit led using 1.2 volt small battery.....

Discussion in 'Electronic Basics' started by Arafat Safdar, Dec 6, 2008.

  1. Hey can some1 tell me how can I lit LED through 1.2 volts battery.I
    Connected 330 ohms resistor in series it works on 5v battery but it
    doesnt work on 1.2 v battery

    Regards,
    ARAFAT SAFDAR
    WWW.ALAGRAS.TK
    trading and contracting
     
  2. Eeyore

    Eeyore Guest

    No it won't. There's not enough forward voltage / current. You might
    just get some light with a 10 ohm resistor. It'll depends on the colour
    of the LED too.

    But as your battery runs down, it'll soon stop glowing.

    http://www.google.com/search?hl=en&...le+battery+led+inverter+schematic&btnG=Search

    Graham
     
  3. Rich Webb

    Rich Webb Guest

    Full do-it-yourself instructions at:
    http://www.cappels.org/dproj/ledpage/leddrv.htm

    You'll need to adjust some component values depending on the
    characteristics of the LED that you're using.
     
  4. neon

    neon

    1,325
    0
    Oct 21, 2006
    Brilliant now you have discovered that LEDS don't work on demands READ THE SPECS!!!
     
  5. Guest

    Hi Graham, I am not well verse with computer terms, however please
    help me retrieve my gmail or teach me how to use google talk.
     
  6. As a rule of thumb, an LED requires 2V across it and 10mA to light it.

    So the example of 5V and 330ohm works like this

    2V across the LED leaving 3V across the resistor.

    3V/330 ohms = 9mA.


    The problem you have is that the LED must have the correct forward voltage
    otherwise it won't no matter what current you put through it.

    As I said this is typically around 2V but varies a little with different
    colours - but 1.2V won't be enough.

    If you really want to light an LED with just a 1.2V source then you will
    need to build a small switch mode step up - but this would seem to be a lot
    of effort to me.

    Cheers,

    Nigel
     
  7. Eeyore

    Eeyore Guest

    This isn't Google Groups. You are using a (poor) interface from Google to
    Usenet.

    In order to do what you want you'll need to learn some basic electrical and
    electronic theory - or just slavishly copy one of the many online designs that
    do what you want. Someone else gave you some links.

    Graham
     
  8. neon

    neon

    1,325
    0
    Oct 21, 2006
    LOOK a LED is a diode and like all diode they follow an exponential curve vs current. the forward voltage can be 1.8v to 5v so a simple 1.2v cannot supply enough forward voltage drop to see the emission of light. 2 BAT. 1.2v depends on the LEDS it just may blow up .SO READ THE SPECIFICATION.
     
  9. default

    default Guest

    http://www.cappels.org/dproj/ledpage/leddrv.htm
    How to light any color led on 1.2 volts
     
  10. Thanx Guys Appreciate your suggestions.. .. Actually i was using 1.5
    volts button cell ... ..
     
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