resistors

SupermotoMX · 3 Mar 2010 at 15:15

okay so i have on my routor (which i added

)

a 5v 60mm fan that pulls about 0.18amps according to the sticker.

well its currently run off usb. so when my pc/laptop is switched on... i plug it in so it stops the routor from locking up due to heat.

ANYWAY long story short. and kinda resistor i could add to bring the voltage down to about 4volts? from a standard 2.0 usb port, as atm the fan is loud.. and pushes WAY more air than is needed.

its a cheap led fan.. which constantly flickers... kinda cool

shroomz · 3 Mar 2010 at 15:19

Keeping the current the same, you would need a ~5 ohm resistor if you connect them in series:
this would keep total power and current the same, but decrease voltage to ~4V across the fan

SupermotoMX · 3 Mar 2010 at 15:29

hmm that means totally nothing to me, would u be able to link something suitable on ebay, im 99% sure your allowed because its not a computer component, and ocuk dont stock resistors.

if this is false and Shroomz or anyone else does link, i accept full responsibility

shroomz · 3 Mar 2010 at 15:46

well, I'm not sure of the actual wiring of it, especially since you get different power ratings for them; you might be better asking in the Modding forum where they should know more.

IKMS · 3 Mar 2010 at 15:48

Means we need to wait for an Admin or a Mod... excellent.

SupermotoMX · 3 Mar 2010 at 15:52

sorry i wasnt sure where to post this

figures general hardware would know, if a mod could move would be awesome.

basicaly its a standard usb lead, with the positive and negative leads stripped and connected to the fan, thats the only thing it will need to power will not be adding more things onto it

guessing a resistor on the positive to restrict something to make the fan turn more slowly so making less noise

bremen1874 · 3 Mar 2010 at 16:08

Get a 5.1 Ohm 0.25 or 0.5 Watt resistor and wire it in series with the positive lead.

It's exactly the same principle as selecting and wiring resistors to get the correct voltage for LEDs. You should be able to find plenty of guides for this.

PhillyDee · 3 Mar 2010 at 16:14

You will not get a standard 5.1 ohm resistor.
Best would be a 4.7 Ohm (or 5.6Ohm). Thats the E12 range anyway!

SupermotoMX · 3 Mar 2010 at 16:20

hmm i found these 2

http://cgi.ebay.co.uk/10-x-4-7-Ohm-...al_Components_Supplies_ET?hash=item1c0fe93326

http://cgi.ebay.co.uk/2-x-4-7-Ohm-3...al_Components_Supplies_ET?hash=item1c0fd26e61

one is 3watts and one is 1.4watts which would be better and why? :X

bremen1874 · 3 Mar 2010 at 16:21

E24 range resistors should be easy enough to get hold of.

If not, as you say, 4.7 or 5.6 Ohm would be okay.

bremen1874 · 3 Mar 2010 at 16:30

one is 3watts and one is 1.4watts which would be better and why? :X

The wattage tells you how much power the resistor is able to dissipate without taking damage. For your application the 3 Watt version is massive overkill but would work exectly the same as the 0.25 Watt version.

SupermotoMX · 3 Mar 2010 at 16:30

bremen1874 said:
E24 range resistors should be easy enough to get hold of.

If not, as you say, 4.7 or 5.6 Ohm would be okay.

for example both of them on ebay are 4.7 OHM. but one is 3 watts and one is 1.4watts which one would i be looking at? or dosnt it matter?

bremen1874 · 3 Mar 2010 at 16:34

for example both of them on ebay are 4.7 OHM. but one is 3 watts and one is 1.4watts which one would i be looking at? or dosnt it matter?

Your link is for a 0.25 Watt resistor not 1.4 Watts. Either will be fine.

PhillyDee · 3 Mar 2010 at 16:35

The 0.25W one is smaller!

MikeHunt79 · 3 Mar 2010 at 16:38

You could also use diodes in series if you only want to drop 1 volt.

bremen1874 · 3 Mar 2010 at 16:46

You could also use diodes in series if you only want to drop 1 volt.

This would probably start a whole new 'which way round do I connect the diodes' thread.