Noozer wrote:

snip

Well, at least you know you don't know anything about electricity.
If the figures you give are accurate (which they aren't, they are
probably maximums) you want about the same ohmage as what the fan
appears to be. This would be about 12 v. / 0.05 A = 240 ohms. All
that really does is give you a ball park number. You may want
anything from about 100 ohms to that. They should probably be at
least 2 watt rated for safety, but have virtually no tolerance
requirements. Get a set of 2 watt carbon resistors, worth about
5 to 10 cents each (but expect to pay more unless you can raid
someones junk box), say 100, 150, 220, 330 ohms and try them out.
No, it doesn't matter which lead they appear in, nor which
direction they are connected in. Ohms and watts are an adequate
specification, and you don't need anything better than 10 or 20%
tolerance.

Just wondering... When trying to slow a fan in a PC, which is better
- using 5v and 12v to get 7v to the fan, or adding a resistor inline?

I've got a Media PC that's very quiet except for one case fan.

You can only use the 12-5=7 trick when the 5 V line has enough load
on it to sink the 7 V current. That will usually be so. However,
that also gives you only one possible operation point, while the
resistor allows you to select what you want, at the cost of a watt
or two.

Please try to get in the habit of preserving attributions for
material you quote.

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