External Power:
Using a adapter 1.5v-12v 300mA. but when the switch is on to 12v and i read the voltage its says around 17v, so i have placed a 12v regulator.
Fan:
12VDC 4.32W
So the fan alone is drawing more than the rated current of the adapter ....
Don
How?
Never mind got it 
p = iv.
So if I get a better power supply, the noise Should go away?
So if I get a better power supply, the noise Should go away?
Not exactly. If you get a better power supply one of your problems will have been corrected. There may be others.
Don
prowler_sn:
Never mind got it
So if I get a better power supply, the noise Should go away?
Get a separate supply and only connect it to the fan, not "to arduino and use Vin". Don't forget to connect the grounds.
Do i just plug in the 12V supply directly into Vin and ground? Arduino uno have two ground pins beside the Vin pin, one of the grnd pin is occupied with the 5v. so do i just place the positive 12v to Vin and negative to the second grnd pin? i know this sounds very silly but i dont want to burn my Arduino i already have blown 1 before. up until now i have just been connecting the the external power supply + to the fan directly (with the help of the regulator) and sharing the grnd with arduino.
do you know of any cheap 12v power supply with sufficient amp?
thanks
cheers
SN
Fan + to separate power 12V, Fan - still to the MOSFET, separate power gnd to arduino gnd and don't connect the SEPARATE power 12V to Arduino Vin! Check dictionary for what separate means.
So what's going inthe Vin ?
Why does anything have to go into Vin? If you power your arduino with usb or power barrel, nothing goes into Vin?
Hi there!
Ok so I got a brand new 12vdc 2500mA external power supply. Im STILL getting the noise when the fan is not running at 255 (full) and the temperature is still jumping ~3 degrees.
when temp is below 23C...nothing happens the fans stays off...no noise,good
when temp is between 24-25 ... run at 200 (~80% of the fan max)...makes noise and the temp just jumps a couple of degrees (did u notice that?)
when temp is above 25...run at full 255...no noise,good.
any help?
thanks in advance and being so patient. if i could just fix this problem..
I think I figured out the problem!!!...
it says that "simulate voltages in between full on (5 Volts) and off (0 Volts)"
but my fan takes 12volts!!...but then it still doesn't make sense because at 255 it runs fine...?