beginner - LED power supply

Discussion in 'General Electronics Chat' started by taj1987, Jun 14, 2011.

  1. taj1987

    Thread Starter New Member

    Jun 14, 2011

    I am at a dead end and could really do with some help.

    I need to power Luxeon LEDs (forward current 700 mA, forward voltage 6.84 V) for an experiment but have absolutely no idea how to power them. I have acces to universal power sources, can I use one of these and attach it with crocodile clips?

    The LED can be found at

    I have found LED power supplies such as but have no idea whatsoever if this would do the job.

    Am I always going to require a resistor with an LED, I was trying to avoid this because I cannot find anyone to help me in person and am completely clueless. I have other LED options 3.0 mW, T-1 3/4 or 7 mW, TO-1 3/4, would these still require resistors?

    I apologise for my lack of knowledge but have contacted all of the suppliers of the LED and power supply that I could find but have had no help
  2. TBayBoy


    May 25, 2011
    Neither of your links appear to be working.
  3. #12


    Nov 30, 2010
    The small LEDs always require resistors. The large ones sometimes have their own protection built in. That is why the links are very important.
  4. SgtWookie


    Jul 17, 2007
    Unfortunately, neither of the links you posted work.

    Your 700mA LED is considered a high-power LED; using a current limiting resistor would waste a considerable amount of power.

    You should investigate using an LED driver such as a BuckPuck:
    BuckPucks are switching current regulators; vastly more efficient than using a fixed resistor or linear regulator, and the current through your LED is very closely controlled.

    There are various versions of BuckPucks; some designed to mount on a PCB, some with wire harnesses, some fixed, some variable, etc.