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Author Topic: custom voltage fans  (Read 2141 times)
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« on: April 14, 2011, 05:29:15 AM »

modifying voltage is the quickest and cheapest way to silence your rig.  and you can buy "12v to 7v" pigtials but draws are not the same on all fans so let's get down to the math and decide where we really want to land as just dropping it to say 10v could be quiet enough for you so why drop your cfm anymore?

Original fan voltage: 12V
Original fan current: 0.2A (Read from sticker on fan)

    V=IR (Ohm's Law), so 12 = 0.2R   =>   R = 12 / 0.2   =   60

Fan resistance: 60 Ohms

Target voltage: 7V

    V=IR (Ohm's Law), so 7 = 60I   =>   I = 7 / 60  =  0.12 (2 d.p.)

Target current: 0.12A

Voltage drop across resistor: 12V - 7V  =  5V

    V=IR (Ohm's Law), so 5 = 0.12R    =>    R = 5 / 0.12   =  42

Target resistance:  42 Ohms

Power dissipated by resistor:  5V * 0.12A  =  0.6W

orig info
/\ theres a nifty calculator at the bottom of the page if you're too lazy to do the equations

I have as much authority as the Pope, I just don't have as many people who believe it. --George Carlin
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