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Power Cable Voltage

By speedy266
Jan 28, 2005
  1. Quick question about power cables, 4 wires...Red1, Black2, Black3, Yellow4.
    1 & 2 complete the circuit and 3 & 4 complete another circuit. I know more voltage flows through 3 & 4. I just wanted to know if someone knew the voltage across those to those 2 sets of points. I have 3 case fans, one originally came crimped into 1 & 2, but im going to splice into 3 & 4 because the other to are that way and they push alot more air. Also i did a test with a christmas light bulb and put it through 1 & 2 and it lit up like normal, 3 & 4 and it was blinding me.
     
  2. RealBlackStuff

    RealBlackStuff TS Rookie Posts: 6,503

    Red=+5v
    Yellow=+12v
    Black=ground
     
  3. Justin

    Justin TS Rookie Posts: 942

    I would advise against powering a 5V fan on 12V. It may be destroyed instantly, or it might break down in a matter of hours or days. Yes, it will spin faster, but you might ruin the fan in the process or greatly accelerate it's death.
     
  4. speedy266

    speedy266 TS Rookie Topic Starter Posts: 23

    Thanks for the info. Another question i have now, is it possible to run the 12V and 5V in parallel or series to the fan? or will that short circuit something. Im guessing there separate circuits and the 12V and 5V cant be hooked up together. 17V would be nice though.
     
  5. Justin

    Justin TS Rookie Posts: 942

    Technically yes you can put them in series and use a single ground and get 17V, however there is no practical use for it unless you get some DC16V fans.
     
  6. speedy266

    speedy266 TS Rookie Topic Starter Posts: 23

    Well I spliced the one fan into the 12V circuit. After reading the fan sticker it says 12V so its safe, i dont know why it was crimped into 5V it was spining slow i could see the blades still, now its running like it should. Thanks for your help.
     
  7. nein

    nein Banned Posts: 109

    If you actually wanted to use low voltage for your 12V fans, bridging 12V and 5V for the differential isn't good. Many 5V power rated electrolytic/tantalum capacitors only have 10V breakdown rating.

    Here's a better low voltage usage method for your 12V fans.
     
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