Voltage of fan

[SpuD]

Hi anyone can help me?
to clarify,
i've got a adaptor which can control the output voltage (1.5-12v) with 500mA.
i've also got a ocean free 2xfan(0.19v, 12v).
if i want to lower the speed of the fan, i'm i suppose to tune the voltage of the adaptor to around 7 volts?

It should not melt the adaptor rite becoz..

2x 0.19A=0.38A
which is less than the supplied Amp that the adaptor can supply 500mA. Rite?

Jus to confirm my calculation.

[zackdelatoonz]

I don't think u can control the output by reducing the voltage. I've tried it and the fans juz stop as soon as I reduce the voltage lower than 12v. But hav heard of people achieving it, juz don't know how they manage to.
But u could try.

It should not melt the adaptor as 500mA = 0.5A

[Goondoo]

You should regulate the current settings, not voltage...... I think

[sherchoo]

Varying the voltage should change the speed of the DC fan. Problem is with these fans they are kinda small and by reducing the voltage you'll be also reducing the excitation field which in turn reduces torque causing the fan to stop turning altogether. I believe if it's a bigger fan, speed can be adjusted via varying the voltage.

Adjusting this voltage should not harm your adaptor. Juz make sure you don't push it higher than 12V if the fan is rated only at 12V.

Goondoo,
It's voltage, not current.

[mok]

yes, you can control the fan speed by changing the voltage as long as it's less than 12V. I'm running 2x80mm 12V PC fan at 4.5V. Recently upped it to 6V due to the hot weather.

[Allen_1971]

Actually, the tuning of these voltages can be pretty screwy... I had one of these DC adapters, and I decided to measure the voltages... they were way off... by at least 30% if I remember correctly... So if you have a multimeter handy, you might wanna probe the voltage across your transformer.

[SpuD]

Thanks for you guys advices,
i manage to tuned my adaptor to 8v and the sound has reduced quite alot, not so noisy.
Me been using the fan for 24/7. Been monitoring the adaptor, it was at a constant temp, not overheating. And the fan providing enough to cool the water (From 30.0 to 27.7)...around 2 degrees. Doing well!