laptop fan help 19v to 12v

Discussion in 'The Projects Forum' started by diesalweasel, Jan 23, 2011.

  1. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    i there i'm lookng to do a fan mod on a laptop
    the fan doesent come in when it should do the fan works if i connect it up to a 12 v supply external

    there no bios up date for it and the battery no good so it run off it charger which i had to modifi you carn't get the parts for it .so i went to maplin and brought a power jack for ir panal mounded single hole 2.5 at 5.5 two wires soldered to the board works a treat
    any way as i was saying it there any way i can transfor 19v 3.16a to 12v so the fan runs strait from the charger i know it would be in all the time but i not bothered about that
    i need to make a small circuit up and it has got to be small to go in side of it

    would a resister work if so wot size would i need

    or something like you get to turn the volume up on your stereo i forget what you call them

    any ideas would be great
    regards jamie
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,148
    3,058
    so, just to be clear, you want a way to run your 12v fan (continuously) off of the 19v power supplied by the external charger?

    There may already be 12v power inside your laptop. Others will know, but I guess your hard drive probably requires 12v. On the odd chance you have a firewire port, those are 12v also.
     
  3. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    that intresting i diddent think of that will give that a try and let you know how i get on

    just on the off chance what about the charger light it a led wounder if i can get power off that

    but thanks for your reply
    many thanks from jay
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,148
    3,058
    If it were me, I'd put the LED on a current limiter off the 19v output. So I wouldn't expect to find much 12v juice there. But you never know.
     
  5. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    hay thankyou every one in here for there help
    i found that the fan could run at a lower power and still be as good
    so it is running of about 2.30 v and run nice
    i got the multi meter out and start haveing a probe at the boart i started with some black rectangle component quite big with a plus on i think that mite be a surface mount resiter so i tested the fan on it and it started the fan happy days. so i took the soldering iron to it and soldered the live to it and the earth to the earth on it board
    it in all the time i don't mind that
    it go off when the machine go off and come on when i switch the machine on doesent seem to efect it .just keep it nice and cool
    any way thankyou every one
    regards jay
    any queston i be willing to anser if some one else wants to do this mod
    the machine back to gether now
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,148
    3,058
    If the big rectangle had a "+" on it, it's probably a surface mount electolytic capacitor. You may have measured 2.3v, but that could be a time-averaged reading of something varying by much more. In other words, what you did would worry me a lot. But, you seem to have gotten away with it. For now. ;)
     
  7. diesalweasel

    Thread Starter New Member

    Aug 28, 2010
    21
    0
    you know what your probaley right i'v just looked at another laptop circuit board and it look i dentical to it on the otherboard it had (c) next to it which stands for a cap i measured it for a wile on power up and it at a constant voltage at 2.3v i wired it to the plus side.
    in fact i'm 100% that your right

    i will let you know later on 2 night
    regards jay
     
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