How to wire a CMF fan

Whats up everyone. I thought i would do a thread showing how to wire a CMF (computer fan). First you will need the following:

1) CMF (computer fan)
2) A/C adapter 12v
3) wire caps

First take your A/C adapter and cut the end off and splice the wires. Then splice the wires on your computer fan. Match the colors of the wires up then screw on your wire caps. In some cases the wire colors wont match up. Like on this one. The black wire goes with black, but the red wire goes with a black wire with white lettering. It can only run one way so if you wire it wrong just switch the wires around and it should work no problem. Also there is a yellow wire you can either cut this off or just leave it. Here are some pics. Sorry about the bad pics. My camera didn't want to focus. EDIT: CMF fans are best used for small grow boxes.

I though I would expand on cmf's and power transformers. Power transformers can be salvaged from many types of home electronics. The small box that plugs into the wall will have a name plate or etched in the plastic a voltage and current rating. (If it doesn't pitch it)


The name plate on the left pack shows the output is 9v (DC symbol) 500mA The right pack is a 12v DC @ 400mA. Either pack can be used but with a 12 volt fan the 9 volt pack would run slower with less cfm.

The fans can be salvaged as well, but you have to take things apart you know with a screwdriver. I have also used a hammer. They will also have a name plate rating.


These are fans from the heatsink of a processor. These are both 12vdc fans and the current ratings are .17A and .19A or to convert to mA(milliamp) 170 mA and 190 mA.

Simple to wire. Works one way. Don't short transformer wires together. Hold together with tape, shrink tube, wire nuts and more. Where the wires come together they are twisted. An extra piece of wire is needed to add second fan.


I use transformer voltages down to 9 vdc. Below that the the fans don't do much air moving for my purpose. Using a lower voltage pack also makes the 12vdc fan more quiet. In my dry box I want the air flow rate to be minimal so a 9vdc power pack works great. In my cabinets I want more air flow so the 12 vdc is needed there. This is one in my flower box. I used wire nuts to bond the wires.


You can also run multiple fans on one transformer. The above fans I round up to make it easy to add. They both run at about 200 mA so the pack needs to have a nameplate rating of 400mA or above. If you have 3 fans going then a 600mA pack is needed. You must also check the nameplate on the fan to check the current.
Some muffin fans salvaged from other things could be a 300mA fan. You wouldn't want to run two of those on a 400mA pack. Another pack I have is 9vdc @100mA. That packs current rating is really too low to even run one fan.

Other thoughts on muffin fans.
Take compressed air when salvaging and blow out all the dust. Helps quiet also.

Good luck salvaging fans and power packs.