fan hook up

[pedecamera]

I found this 12 v dc fan in a surplus store ( cheap)
it has 3 wires red, black and white
I would think black is " + " and the red " - " the white ??
do I have it right?
I know this is not an electrical forum.... but you guys have been building these great setups... somebody should know.
I e-mailed the company and they gave one crazy answer
quote"
Third wire lead=Sensor
Sensor : rpm, alarm, lock rotor...
If you don't have any reading/monitoring for the fan, the third wire can be leave alone. " end quote
Cheers
Peter

[Ross]

The PC fans I have only have a red and a black lead - no third wire. So I think you can ognore the white. Now, being a DC fan, if it is hooked up one way, fan will push, but if hooked up opposite it will pull. Should be easy to figure out.

[Dorothy]

Is one a ground ?

[Ross]

Originally Posted by Dorothy

Is one a ground ?

With PC fans (DC) one is hot, one is ground, yes. The third is for logic like speed control, etc.

[pedecamera]

so the white would be ground or neg?
the black pos and the red to add some speed ?
I know I can try but I rather know and not burn the thing out before I use it... The surplus store has a whole box ... but ...don't like to buy them all...lol

[pedecamera]

forgot but I am sure you have it right I think its a pc fan

[Ely]

From what little I know about electronics, the black wire is negative, the red wire is positive (hot) and the white is neutral. The negative is the grounding wire, don't hold it while trying to figure out how to wire in the positive, or you become the ground and get the the shock of your life (120 volts). If your fan is a PC fan you should be able to power it with 12 volts, like a car battery. You can use a small 9 volt battery ot touch the leads to the terminals to figure out which one is which. With nine volts it will not run as fast or as powerful. It also has to deal with amperage, but you'll get the main idea by just trying it out.

[pedecamera]

good idea... and no burning it out right away....thanks
peter

[flhiker]

Hi Peter, If your fan is 12 volt dc the red and black wire are the power leads and can be reversed ie if the red lead is on the + and the black on the - the fan will run clockwise and reversed the leads and the fan will run counter clockwise. The white wire sends a signal back to the computer so it can tell if the fan is running or how fast it is running (rpm). Not all computers have that capibility. You can get a inexpensive transformer the puts out 12 volts dc to power the fan without having a battery