laptop fan help 19v to 12v

Thread Starter

diesalweasel

Joined Aug 28, 2010
36
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
 

wayneh

Joined Sep 9, 2010
17,496
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.
 

Thread Starter

diesalweasel

Joined Aug 28, 2010
36
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
 

wayneh

Joined Sep 9, 2010
17,496
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.
 

Thread Starter

diesalweasel

Joined Aug 28, 2010
36
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
 

wayneh

Joined Sep 9, 2010
17,496
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. ;)
 

Thread Starter

diesalweasel

Joined Aug 28, 2010
36
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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