Power resistor help (novice)
Power resistor help (novice)
Hi.
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.
Thanks.
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.
Thanks.
Re: Power resistor help (novice)
This is an exercise in Ohm's Law, and there are calculators for this (and many other things) on this site. Look at the LHS of the banner at the top of this page.
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.
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.
Re: Power resistor help (novice)
@David Thankyou for your guidance.
 Attachments

 ebea4109b355dc8428cce40365df84f8.jpg (65.79 KiB) Viewed 418 times