Electronics max, safe voltage and current from mobo headers

Discussion in 'Modding' started by Splynncryth, 2 Jun 2003.

  1. Splynncryth

    Splynncryth 0x665E3FF6,0x46CC,...

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    I got some LEDs I want to install in my case, but they are 3.4 volt, 25mA max rated LEDs. Will the headers handle this, or should I get a few opticouplers or transistors and set somthing up that way? ( have a bunch of 2n2222s that I bought for labs last semester)
     
    Splynncryth, 2 Jun 2003
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  2. NiHiLiST

    NiHiLiST New-born car whore

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    No, the headers will be absolutely fine with about 15 or so connected even. Just remember your resistors so you don't blow the LEDs.
     
    NiHiLiST, 2 Jun 2003
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  3. Splynncryth

    Splynncryth 0x665E3FF6,0x46CC,...

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    here's one for ya, with what I'm using now with my LED, I'm not satisfied with its brightness. These hings can usally have a normal LED put on them strait, so what if I use one and measure the voltage and current. Assuming the supply is 5 volts regulated, I should be able to develop a thevinin equivelent model and get a value for the internal current limiting resistor right?
     
    Splynncryth, 8 Jun 2003
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  4. SteveyG

    SteveyG Electromodder

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    Are you talking about the Power/HDD/Sleep LED headers on the motherboard or the fan headers?

    If you wanted to connect them to the fan headers, you'd need to use a 344 ohm resistor. This would enable the LED to work at its maximum brightness.

    If you are wanting to run these LED's from a header designed for an LED and are not happy with it's brightness, your best bet would be to use an optocoupler, and then connect the transistor side to an LED, 344 ohm resistor and between GND and +12V to allow you to get the maximum brightness.
     
    SteveyG, 8 Jun 2003
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  5. Splynncryth

    Splynncryth 0x665E3FF6,0x46CC,...

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    I'm refering to the headers for the indicators like the HDD, power, ect headers. I got some violet LEDs to mess with. (there is soooooo much blue out there, I want to be different) I have one on a HDD header now with a 100 ohm current limiting resistor. But if there is already any current limiting on the connection then the 100 ohm is only adding to the resistance.
    According to the specs, they are rated for 120mcd, but unless you look at the LED directlely, it is difficult to see anything.
    Th opticouler is an obvious sulution, but I wanted to know if I could simply 'plug and play'.
    the current circuit is like this to clear up any confuction

    HDD+--\/\/\/----->|----HDD-
    ______100_______3.4v
    ________________25mA max
    Sorry, I couldn't find a null charicter that worked. I don't know what font is being used here.

    The LED is mouser part number 696-ssl-lx5093uvc
     
    Last edited: 8 Jun 2003
    Splynncryth, 8 Jun 2003
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