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> Wondering About Doing A Certain 12volt Fan Mod, taking 12 volt down to 9 volt ??
wilgo45
post Sep 16 2012, 05:08 AM
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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 ?
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Weirdjerz3y
post Sep 16 2012, 06:07 AM
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http://forums.xbox-scene.com/index.php?showtopic=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.
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relaxxx
post Sep 16 2012, 01:34 PM
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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.

http://www.youtube.com/watch?v=lC2OWCEzvaY


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.

This post has been edited by relaxxx: Sep 16 2012, 01:44 PM
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wilgo45
post Sep 16 2012, 04:03 PM
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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 ?
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xboxhaxorz
post Sep 22 2012, 11:53 AM
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QUOTE(relaxxx @ Sep 16 2012, 08:34 AM) *

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.

http://www.youtube.com/watch?v=lC2OWCEzvaY
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
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wilgo45
post Sep 22 2012, 01:56 PM
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QUOTE(xboxhaxorz @ Sep 22 2012, 05:53 AM) *

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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