3-Wire CPU Fan wiring

Discussion in 'Grow Room Design/Setup' started by elemaoh, Feb 15, 2009.

  1. How do I wire a 3-wire CPU Case fan to a regular plug? The Fan has 3 wires (Red,Black,White) and is a DC 12v, 0.3A fan. I cut the end off and tried connecting it to an:

    "AC Adaptor"
    "Class 2 Power Supply"
    Input: 120VAC 60hz 15W
    Output 12VDC 600mA

    The plug has 2 wires. I can get the fan to budge a bit if I have the Red to + Black to - and touch the white to the Red/+ but it wont stay moving. What am I doing wrong?!

    Example of the fan (My wire is white rather than yellow)

    And the AC Adaptor

  2. cut the power cable, attach the red from the fan to the black with white stripe from the adapter, then attach the black from the fan to the all black on the adapter. the white is a speed sensor that usually goes to the motherboard.
  3. Yeah, Ive got that done but the fan wont seem to stay going. If I tap the white wire to red - It budges but thats abot it. Is there a way I can rig up that white wire to something?
  4. I don't believe there is, it should work with just the two. Make sure your wires are connected, not just held together. Good connections matter. Could be your ac adaptor has gone haywire? good luck!
    • Like Like x 1
  5. Not trying to hijack the thread, but Is there a way to add a speed controller? And what would be good to use; how can I wire it?

  6. Why not just find an old, unused PC power supply? Plug n play right there :p No speed control, but if you're like me and have PC parts layin around it's a free/cheap alternative
  7. you said just hook up the cpu fan str8 to the power supply, can you show me which wires to hook the fan to?
  8. could it be because your using a .6 amp adapter with a .3 amp fan?
  9. I wouldn't think so. amps is like water pressure. you must always have enough, but more doesn't hurt.

    now, I fried a fan because I hooked a .85 amp (850 MA) fan up to a 450 MA 12vDC adapter. I should of used a 1A (1000MA) 12vDC adapter and I would of been fine.

    As for the OP.. I suspect he fried his diode circuit when hooking up the sensor (white wire) to power. shouldn't of touched that wire.

  10. so your saying you can fry a fan if its underpowered amps wise?
  11. i have a 13.5v ac/dc adapter and a 12v fan is it ok to wire it to that?
  12. The dc converter will only use a couple watts of electric and cost maybe $1.50 a month to run.

    A PC Power supply will use 1000 times more watts. IE 250 watt PC Power Supply uses 250 watts = $25.20 a month running 24/7 and .14 cents a KW

    Just my 2 cents (Pardon Pun)

  13. Sorry to resurrect this thread, but I was having the same problem and came across this... which I'm sorry to say is exactly wrong. Well, you're using the right analogy, but drawing the opposite conclusion.

    Consider the water pipe. The pressure of the water is analagous to voltage, not amperage. Amperage (often called current) is the speed of water that is passing by at any time. The amount of water that comes out of the pipe in a given amount of time is then the speed times the pressure; consequentially, the power of the circuit to do work (i.e. apply power to an inductive load such as a motor) is wattage, volts times amps.

    With that, consider we want to turn a water wheel, and to do that we need to put 500 gallons of water per minute on it. We have a pipe capable of delivering enough water to turn the wheel. If we send the water down the line at too high a pressure, say 100psi, the pressure will crack the pipe; in electrical terms, the EM field of the wiring will become unstable and break free, often manifested by sparks, arcs, and the blue smoke of death. But if we send it down the pipe at too low a pressure, the wheel won't turn. So, undervoltage = nothing happens, overvoltage = something happens alright, and it's very bad juju.

    With amps, say we have a main water line from the city that is capable of delivering 1000 gallons/min. We're only using 500, so the other 500 stay in reserve. But say it can only deliver 50 gallons/min...again, no workee. So with amps, overamperage is okay, because the component will only draw what it requires. Your house's main line from the grid is capable of delivering tens of thousands of amps, but it only actually draws as much as you do. Underamperage yields the same as undervoltage, namely, nada.

    So you are correct that you should've used a higher-amperage transformer of at LEAST 1A, but using an underamped supply wouldn't have killed your fan. Maybe it's not a 12V fan? 12V is pretty beefy for a case fan, you may have killed it there by overvolting it. Or it was dead to begin with. But underamping it was not the COD.

    No! This is a recipe for a dead fan. See above.

    This is why you shouldn't post advice that you know little to nothing about, especially when it comes to electricity which, need I remind you, is very freakin' dangerous when you don't know what you're doing. Stay smart, stay safe, and never cross the streams. :D

    As for my problem, I'm sure it's just a bum fan. Aw, darn, I have to go peruse computer parts. Tragedy.
  14. Okay, so would this adapter work with this fan?

    Adapter output 12VDC 750mA

    Fan 12V 0.19A
  15. yes just did it meself in like 8 mins
  16. its also easier if you just gut the fan out of a puter powersupply only 2 wires red and black
  17. You should be using a switch mode or switching power supply as well. Others will not always produce their rated 12v output and CAN burn your fan. You should make sure your power supply is rated at the SAME Voltage as your fan but for more amps (or watts) then your fan requires as well. You dont want to run your power supply at 100% 24/7
  18. I agree with the thing about the voltage but you can also plug it into a powerstripe that is pluged in to your timer i just did this last night and it works great
  19. Just strip your wires a little bit then just connect the black and red cord to a 12 volt battery and your good to go

Share This Page