i have 10 x 12v 0.14amp computer fans i need to quieten down.
What I want to do is splice 1 of their molex cables 12v line to include a resistor to decrease the voltage from 12 volts down to 9v.
basically its 10 fans plugged in together making a total of 1.4 Amps @ 12 volts.
I was thinking of using a 2 amp resistor but I do not know what kind of resistor or value to use.
Can someone tell me please and tell me if there's a calculator for this kind of thing.
You need a resistor which will drop 3V at 1.4A. The nearest value is 2.2 ohms, and resistors with this value are easily available. it will be passing a current of 1.4A, and therefore will dissipate 3 x 1.4 = 4.2 watts. You could use a 5W wire wound resistor, but it would get hot - it would be better to use a 7 or 10W one and the price should not be excessive. Make sure that the heat from the resistor does not affect anything in the vicinity. You could use 10 x 22 ohm 1 W resistors in parallel or one for each fan if you wished.