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Connect small transformer to fan

CyrilReboul Posted messages 19 Registration date   Status Member Last intervention   -  
fmq Posted messages 4899 Registration date   Status Contributor Last intervention   -
Hello,

I have a pebble in my shoe and it's starting to get tiring :-)

I need to connect a small AC/DC transformer 12 V to a 12 V computer fan as well.
The transformer provides 3 A and the fan draws 0.17, so there should be no issue; it should work.
But ... :-)
So far, it doesn't seem too bad except when it comes to connecting the wires.

When stripping the wire of the transformer, it's not straightforward because it's a jack plug: There's a coated wire inside a stripped wire, and no ground wire. In other words, 2 wires: one coated and the other not, which is wrapped around the first one.

For the transformer wire, there are 4 strands: one black, one yellow, one green, one blue.
I test each of the wires on all possible connections to the transformer wires and there's no movement.

Of course, I checked if the current is coming out of the transformer ;-)
Any ideas on the solution?

Thanks

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6 answers

  1.
    fmq Posted messages 4899 Registration date   Status Contributor Last intervention   721
     
    evening

    same conclusion


    cia ciao

    --
    it's a good day to live today!
    3
    1. fmq Posted messages 4899 Registration date   Status Contributor Last intervention   721
       
      little test to connect the yellow and blue wires together
      for a brief moment put to at most one battery

      brief contact...just to see if the fan turns


      will it pass or will it smoke!!

      ciao ciao
      0
    2. CyrilReboul Posted messages 19 Registration date   Status Member Last intervention   2
       
      Okay. Thanks.
      It doesn’t work and it doesn’t smoke ;-)
      A tech friend in IT explained to me that it’s probably because this kind of 4-wire connection needs to be plugged directly into the motherboard since these are fans dedicated to its cooling and it's the motherboard that should manage the power supply. I find it a bit hard to swallow, but that's the only explanation I have.
      ...
      0
    3. vieu bison boiteu Posted messages 44334 Registration date   Status Contributor Last intervention   3 591
       
      Intel CPU processors manage a square signal for rotation speed
      it's the variation of t that affects the rotation speed
      t short = low rotation speed
      t long = high rotation speed

      and t is always less than T ; about 80% max for high speed ; and about 20% min for low speed

      for you, you would need a chassis fan or an AMD fan or a separately purchased heatsink fan ; which manage a voltage level between +5 volts and +12 volts
      0