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  1. riffraff

    Cree P4 under-cabinet lights with dc power supply

    Should be okay, but there's a greater likelihood of the brightness being different (due to differences in the performance of the junctions, a difference which is minimized in a parallel circuit). You're looking at a 2.2 ohm resistor of about 3 watts (to be safe; don't want to set fire to the...
  2. riffraff

    Cree P4 under-cabinet lights with dc power supply

    Have a look here for a series/parallel LED calculator. If you have two LEDs drawing 800mA each, that's 1.6 Amps. You gonna need a bigger boat, er, supply, rather. :popcorn:
  3. riffraff

    Cree P4 under-cabinet lights with dc power supply

    UL = Underwriters Laboratories. Required for just about anything that connects to house current (certainly all consumer goods). Most of the wall warts are not regulated, so you may not be getting a true 4.5VDC. You said you saw it go up to 1.5 Amps...I assume you have a multimeter? Do you...
  4. riffraff

    Cree P4 under-cabinet lights with dc power supply

    The problem with LEDs and water analogies is that water acts in linear fashion, whilst LEDs (being a semiconductor junction) are exponential. That's why the OP needed a resistor from the very beginning, even if he was to find a 3.7VDC supply that would "work." A change in voltage across the...
  5. riffraff

    Cree P4 under-cabinet lights with dc power supply

    Many supplies will exceed their current ratings as they approach a shorted condition, but their voltage will sag at the same time. BTW, when you say, "Radio Shack power supply set to 4.5VDC," are you talking about the wall warts (wall transformers)?
  6. riffraff

    Has anyone purchased any of those 110v LEDs for home use?

    Hmmmm. I'm not really sure a dog and cat needs a light left on...well, not the cat, anyway. Aren't they rather known for their ability to "see in the dark?" :thinking:

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