LED Voltage

Discussion in 'The Projects Forum' started by torpedochief, Apr 22, 2010.

  1. torpedochief

    Thread Starter Senior Member

    Mar 30, 2008
    124
    6
    I have a sorted number of LEDs. How do I determine required voltage? Also are the voltages different for RED, GREEN, WHITE?

    Thanks friends you guys are of enormous help!

    Don
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    Each of your LEDs will have a foreward voltage drop (1.8V ~ 3.2V, aroud there). The LEDs have internal resistance, which forms that voltage drop across each individual LED. Being the case, I would suggest that you connect a 5V source in series with a 250Ω resistor and LED. Then, take a voltmeter and measure the voltage drop across each of your LEDs. Once you know that, you can calculate the full brilliance of light:

    \frac{V_I_N - V_F}{I_F} = R

    Where Vin = 5V
    Vf = Foreward voltage you previously found out with a voltmeter.
    R = Resistance you end up needing in that series circuit I mentioned.

    Austin
     
    torpedochief likes this.
  3. torpedochief

    Thread Starter Senior Member

    Mar 30, 2008
    124
    6
    Just the info I needed! Thanks Austin!

    Don
     
  4. bertus

    Administrator

    Apr 5, 2008
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