GB BOY COLOUR irritating power LED

Discussion in 'Other Handhelds' started by romanaOne, May 3, 2014.

  1. romanaOne
    OP

    romanaOne GBAtemp Regular

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    where the potential goes to zero
    I got one of these knock-offs on ali baba and it works well. I tried a bunch of games on the 64 megabit smart card and they all work ok. Yes, there are a few minor graphics defects- Link kind of tears when he walks around in Zelda--but overall, it is amazing to be able to actually see the screen on a GBC in my favorite games! In darkness, the screen is even a little too bright.

    Does anyone else notice that the red power LED is bright as all hell? I put a piece of black electrical tape over it. But that LED is probably wasting 30mA, or about 1 to 2 % of the current in a 2400 mAh NIMH AA. (I don't know the true capacity of the batteries, but I'll bet it is less than what's scrawled on the side. Salesmans' mAh, LOL.)

    Then I noticed the Smart Card has a big bright green LED that lights up when you are using bank 2. Not too annoying since it's on the back, but there goes another 30+ mA....

    So LEDs are wasting like 5% of the battery and they're annoying.

    That's assuming a BRAND NEW set of NiMH batteries. Nominally, the LEDs are probably drawing closer to 10%.

    What would be a good current-limiting resistor to replace them with? i.e. what is the resistance of a forward biased LED and will it mess anything up if I replace the LED with a larger resistance?
     
  2. mikeyt1998

    mikeyt1998 YouTube Glitcher

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    In response to: 'Will it mess anything up if replaced'

    I don't think that replacing it with another LED of larger resistance would cause any harm, I imagine that the circuit that the LED comes from is literally just to indicate that the GBC is turned on, but then I don't know the circuitry for a GBC so can't be 100%... :(
     
  3. WigWrm

    WigWrm GBAtemp Regular

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    I=V/R. I around 3-5mA will significantly reduce the brightness. Assuming this runs off of 3.3V then, .005=3.3/R and R=3.3/.005 = 660 ohms.

    The resistance of the diode when it is on should be negligible (mili ohms to under 10 ohm range).

    Seems like Vcc might be 5V, so.....
    5/.005 = R = 1000 ohms or 1kohm (when I = 5mA)
    5./003 = R = 1666 ohms or 1.67kohm (when I = 3mA)
     
  4. cracker

    cracker Nyah!

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    Yoi could always totally remove the power LED since it is basically useless as you can tell if the GBC is on or not.
     
    pelago likes this.