Using my old scanner DC adaptor to power my 120mm Xigmatek 12V fan.

The OUTPUT is 12V 1.25A

if I connect direct to the fan will it damage the fan?

(P.S. Not using the fan in the PC)

no problem if the adapter has auto switching feature... like PSU...

err... adapter was for my scanner(rosak already). Not sure if have switching feature. Just say Output 12V 1.25A.

If use too high Amp for the fan, what will happen?

the 1.25 A stands for this adapter outputs at 12volts with maximum current rating of 1.25A.

If your device draws above 1.25 A , it will burn the adapter as your device exceeds the maximum rated current for the adaptor.

I know that but what happens if the device dont use so much power (eg. only 0.45A) Will it damage the device(fan)?

nothing will happen as already mentioned.

your fan only draws 0.45A at full speed, and your adaptor is capable of supplying up to 1.25A.

Its rated 1.25A, it doesn't mean that it is supplying 1.25A into your device, it only mean you can use any device with it provided that device does not draw above 1.25A.

Thanks. I get it now. Cause I asked some ppl and they said that it will damage the device if supplying too much Ampere.

y not just jump start the fan using PSU ?
if u think its not safe, then jump start la better

DO NOT plug an adaptor rated at 1.25A output into your fan. It will burn it. Initially, i also thought 1.25A means it's the maximum your device can draw from it, apparently i was wrong, or something else went wrong. I tried twice (using router adaptor, also 1A or 1.2A i think), on 2 different fans, the first time the fan simply fan very fast for few seconds and then stopped, and never spin again. I thought fan problem. Second time, i did it again on another spare fan, this time the fan come out smoke, so i know i used too much amp, which i already suspected before i even start. Burnt 2 fans for nothing but learn a valuable lesson I tried it on processor fan by the way(both of them), they are rated at 12V 300mA-500mA each if i am not wrong.

I think 500mA is fine. I wouldnt dare to try anything higher than that. Look at the sticker on your fan, see how much is it rated. Try not to exceed it. A bit is ok though i think.

This post has been edited by gzero: Jul 2 2010, 10:41 AM

that is due to few things, other than current rating that might potentially burn your fan
1) Your adaptor although stated voltage rating of 12V (lets say 12) , in actual fact it might supply higher voltage (+-1->3v) . This is true, get a multimeter to check it, usually your device able to tolerate it as the device will have built in regulator, for fan it depends. Also depends on the adapter, its +- voltage. Usually those high rpm fans, dont need to put exact 12V as most probably you wont want to run full speed else you will hear jet engine everyday.

2) Reverse polarity ? Positive lead to negative lead of the fan etc...

perhaps a better explanation from another ppl
http://answers.yahoo.com/question/index?qi...27102318AANXUyS

Lets think about computer power supply. Get one cap ayam PSU and one good PSU true power 600W above.
Compare the current rating for each of the 12Vdc, 5v,3.3v on the label. You will see the good PSU 600W above has a higher current rating capacity(depending on the Watt, usually higher wattage will get higher rating). Are you saying those high powered PSU will burn all your computer parts if plugged in?

This post has been edited by khtan2000: Jul 2 2010, 10:56 AM

there are two types of adapter, one is regulated, and other is normal one. You can easily identify using multimeter. For non-regulated adapter, use a resistor.

put 3amp and its will going wild...hurricane