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Electronics How to make fans run at 7v?

Discussion in 'Modding' started by talladega, 26 Mar 2009.

  1. cpemma

    cpemma Ecky thump

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    True, but note use a 5V zener (5.1V is usually the nearest stock value) to leave 7V at the fan as required, not the 7V one you've shown, and you've drawn it the wrong way round - banded (pointed) end of a zener goes to V+ supply, or it just drops 0.7V or so.

    The 5W zeners are a bit scarcer than 1.3W but if you can find a handy supplier, go for it.
     
  2. jrs77

    jrs77 Well-Known Member

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    You would need a much bigger diode there to make it work this way. 4x 120mm fans require more then 5 Watts.

    So you're looking for something like NTE5176A / NTE5177A (10 Watts).
     
  3. cpemma

    cpemma Ecky thump

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    See post #9

    They're 3W fans @12V = 250mA, drawing approx 146mA @7V, four fans so 583mA flowing through zener, dropping 5.1V = 2.9W; plenty of safety factor left. ;)
     
  4. jrs77

    jrs77 Well-Known Member

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    Yeah, was a little bit too fast just counting the initial 3 Watts and not calculating it really :duh:
     
  5. talladega

    talladega I'm Squidward

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    Ya, I had thought of using a 5w diode but I didn't want to be ordering from so many different sites as in the end it turns out to be more money from shipping so many orders.
     
  6. hydro_electric_655

    hydro_electric_655 Dremelly Dude

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    I do realize the diode is backwards, I just used a quick online circuit tester and didn't know how to rotate it. Oops about the wrong rating.

    There are actually quite a few places I found selling 5W 5.1V zener diodes.
     

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