Introduction: Slow Down Pwm Fans Without a Controller

Picture of Slow Down Pwm Fans Without a Controller

Got some of those 4 wire fans that you want to slow down? today is your lucky chance
(works with most PWM fans including some Sunon maglev)

sorry for the lack of images so I'll try and describe it as best as I can

equipment:
one PWM fan
2 on off switches
some wire
soldering iron
solder
a sharp object for cutting and skinning wire (scissors basically)

Step 1: Plug

Picture of Plug

the fan will not be suitable for use in a PC again unless you solder the plug back on

so the first thing your going to want to do is get a sharp utensil e.g. pair of scissors and chop the wire about 3 cm from the plug (if you want to use it in a computer) and skin the wires on the plug and the fan's cable

Step 2: Switches

Picture of Switches

warm your soldering iron and prepare some solder and wire and have your three switches at hand, I recommend labelling your switches: 1,2,3 with a pen or something

take the red wire from the fan and solder it to one of the terminals on switch 1and solder another wire onto the other terminal

take the blue wire and solder 2 wires onto it in a Y configuration so you have 2 blue wires, do the same for the black wire but use 2 black wires instead

so you should have 2 black wires and 2 blue wires coming off the fan

solder one of the blue wires onto the first terminal of switch 2

solder the yellow wire to the other terminal of switch 2

solder one of the black wires onto the first terminal of switch 3

solder the other blue wire onto the other terminal of switch 3

to power your PWM fan, positive goes to red and negative goes to red, here's what the switches do:
switch 1: on/off
switch 2:medium speed
switch 3:low speed (lowest fan will spin and not stall)

here's some switch combination to help you out

switch 1:on
switch 2:off
switch 3:off
fan runs at full power

switch 1:on
switch 2:on
switch 3:off
fan runs at medium speed

switch 1:on
switch 2:off
switch 3:on
fan runs at it's slowest

Step 3: What to Do If Your Going to Use in a PC?

Picture of What to Do If Your Going to Use in a PC?

if your going to put it in a PC again, take the plug and solder the red wire from the plug onto the red wire of the fan, and then solder the black wire of the plug onto the black wire of the fan. leave the other wires on the plug alone/cut them off

Comments

easymods45 (author)2015-12-23

remember, if you do this to one of your fans and it doesn't work, I am not responsible

this mod does NOT work with all PWM fans

easymods45 (author)2015-12-23

it works on the principle of dividing the voltage between switches

easymods45 (author)2015-12-23

and @dan3008 yes I meant negative to black

easymods45 (author)2015-12-23

thanks, this is my first instructable, you can follow me if you want to for more little projects, I'm making a amplifier next

dan3008 (author)2015-12-22

"to power your PWM fan, positive goes to red and negative goes to red" surly you mean negative to black?

Nice build anyway, basically a voltage devider?

tomatoskins (author)2015-12-22

Really interesting information!

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