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Modding VOltage comming outa the HDD led pins on mobo..

Discussion in 'Modding' started by Jii Dee, 2 Oct 2002.

  1. Jii Dee

    Jii Dee What's a Dremel?

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    Any idea what it is? i'm gonna be using it with some ttl logic so i need to know if i must knock it down a bit..
     
    Jii Dee, 2 Oct 2002
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  2. txi

    txi What's a Dremel?

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    iguess, it is some 3volts or smth, cuz that's the general operating voltage of most usual leds.. i don't think it is 5v, cuz then you wouldn't be able to change led's and it won't be a standard then. maybe the atx form factor standard will help you some? can't recall the exact url right now, but i have seen it on these forums...imho
     
    txi, 2 Oct 2002
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  3. FuzzyOne

    FuzzyOne ⎃

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    Ive just Bl0000'ed my cases power and hdd led's and the header on the abit motherboard was putting 5v per led's, The best thing to do is get some resitors and test it with them connected first if its too dim simply remove the resitor's. :cooldude:
     
    FuzzyOne, 2 Oct 2002
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  4. cderalow

    cderalow bondage master!

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    most HDD/power headers on motherboards are in the 3-3.5V range... as long as the LED minimum voltage is below there the LED will light, regardless of if it says the LEDis 5V as normally a 5V LED is a regular LED with a resistor inline all ready so the drop across both is 5V...
     
    cderalow, 2 Oct 2002
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  5. ndtinker

    ndtinker Car Washoholic

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    The most I've seen the HDD LED hit was around 4.6v, so it's safe to say 5v, at least that's what my old Asus was putting out.

    Even still, the HDD light dosen't usually stay on long enough to get up to 5v, so running a LED at a higher voltage probably won't hurt it.
     
    ndtinker, 2 Oct 2002
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  6. Jii Dee

    Jii Dee What's a Dremel?

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    thanks for all the replies. ALl those voltages are well within the 5v limit of ttl chips. so im ok . :p Now i just have to find a connecter to that'll fit the mobo's HDD Status Header....*trolls through the maplin catalogue*:confused:
     
    Jii Dee, 2 Oct 2002
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  7. pheonix

    pheonix Toot Toot!

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    5v
     
    pheonix, 3 Oct 2002
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  8. ZapWizard

    ZapWizard Enter the Mod Matrix

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    Read my guide on harddrive LED's
    www.zapwizard.com/ide

    (The motherboard isn't even need at all!!!)
    Here's a schematic of the LED header on a motherboard
    (This was taken directly from an MSI board, but is the same on all motherboards, I use this on my Soyo)

    [​IMG]

    The Voltage for the LED's comes from VCC (Typicaly 2.5-3.5volts)
    It is routed through a 33ohm resistor, to the Posative lead on the LED, then the negative side of the LED is connected to Pin39 on the IDE cable.

    (You can bypass all this and go straight to the harddrive)
    Pin39 is pulled to ground when ever the harddrive is active.
     
    ZapWizard, 3 Oct 2002
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  9. linear

    linear Minimodder

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    And if for whatever reason you have trouble interfacing to TTL, an optocoupler would be a handy widget.

    Note also that the signal is active low as observed by ZapWizard, so take that into account in your logic design.
     
    linear, 3 Oct 2002
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