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Wondering About Doing A Certain 12volt Fan Mod


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#1 wilgo45

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Posted 16 September 2012 - 05:08 AM

Considering doing a certain style of 12 volt fan mod.

Taking 12 volts from the bottom side of the power plug in. But what I want to do is trim the power down to 9 volts before entering the fans.

Now, I could do the rheostat method. Nothing wrong about that.

But I am wondering about just putting a resistor inline on the positive wires going to the fan set.

What ohm of resistance would I need to knock 12 volt down to 9 ?

#2 Weirdjerz3y

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Posted 16 September 2012 - 06:07 AM

http://forums.xbox-s...howtopic=637955
At top it says for 7v or 9volts, you can try that. If you really want it your current way, there's a bunch of ohm calculators you can use. from google.

#3 relaxxx

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Posted 16 September 2012 - 01:34 PM

My favorite method is to use 2n3904 transistors to lower voltage. They cost pennies and each one in series drops nearly 1V. So 3 in series from 12V source ~ 9V. Beats pulling the board out and loading mosfets. They can handle 1A fans without even getting warm.




BTW for resistors: Watts = Amps X Volts. So for fat console fans looking to drop 3V; Watts = 09.A X 3V, you need a 2.7 watt resistor. You can probably buy 500 transistors for cheaper.

Edited by relaxxx, 16 September 2012 - 01:44 PM.


#4 wilgo45

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Posted 16 September 2012 - 04:03 PM

What about places where I can get a reliable 3 volts from ?

Don't want to take from Power Regs - seems like a bad idea.

If I put 12 volts on my positive line and 3 volts on my ground line, I'll get 9 volts on a fan set.

what about those unused junction ports ?

#5 xboxhaxorz

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Posted 22 September 2012 - 11:53 AM

QUOTE(relaxxx @ Sep 16 2012, 08:34 AM) View Post

My favorite method is to use 2n3904 transistors to lower voltage. They cost pennies and each one in series drops nearly 1V. So 3 in series from 12V source ~ 9V. Beats pulling the board out and loading mosfets. They can handle 1A fans without even getting warm.


BTW for resistors: Watts = Amps X Volts. So for fat console fans looking to drop 3V; Watts = 09.A X 3V, you need a 2.7 watt resistor. You can probably buy 500 transistors for cheaper.


makes sense will keep this in mind

i just do the 12v fan mod and then ground to a 3v point

#6 wilgo45

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Posted 22 September 2012 - 01:56 PM

QUOTE(xboxhaxorz @ Sep 22 2012, 05:53 AM) View Post

makes sense will keep this in mind

i just do the 12v fan mod and then ground to a 3v point



Are all the safe / usable 3v spots on the back side of Power regs ?

Doesn't seem practical to piggy back on those drain sides, but if its OK ... someone just say




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