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Cheap computer fan speed controller used to slow the speed of a DC motor? Answered

I've got a cheap 12 VDC computer fan speed controller (adjusts from 5v to 12v) rated at 1000mA. It's designed to be plugged into a computer motherboard with a 4 wire plug.(green, yellow, black, and blue). It also has an output socket for a fan...looks like 3 wire. I'd like to provide the input of the speed controller with a 2 wire (+ and -) 12VDC, 3A power supply that plugs into a wall socket (110 VAC). I'd like to then use the output socket on the controller to power a 2 wire (+ and -) 12VDC motor (rated at .03A) in order to change its speed. Is this even possible? Is the controller considered a PWM controller? The instructions on the controller says the blue wire is the "control" wire. How would I wire up these components? (110VAC 12VDC power supply, 5v to 12VDC fan speed controller, 12VDC motor).

Discussions

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Downunder35m

19 days ago

I guess the controller is just some adjustable voltage regulator but if so than it would be better for your purpose anyways.
As the controller is rated for 1A it should have no problems to provide at least 0.5A without getting too hot - and that is more than your motor would need.
Assuming the wire colors are correct and the controller has no additional plug or similar:
Black is ground/negative.
Yellow is 12V+
Green and blue are the motor connections.
Reversing the last two will change the direction of your motor.

I don't know if your instructions came with a proper wiring diagram, in case they did then please provide then here.
"Control" in Chinglish can be both the positive wire for the motor and the wire for the speed sensor of a fan motor.
From experience however I would say the stuff in the first part I wrote should be correct and combined with your "instructions" I assume blue should go on red for the motor and green on black of the motor.
If in doubt crank it down and try it out, not much bad can happen.

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SpringsdudeDownunder35m

Reply 18 days ago

Thanks so much for your reply!
I was under the assumption that, under normal usage as a computer fan controller, the 4 wired plug coming off one end of the controller would plug into a motherboard...making that the input. On the other end of the controller is a recessed socket (no wires) with 3 conductors (exactly like the image provided, but recessed). I assumed this recessed socket was the output that a fan would plug into. I have no idea which 2 of the 3 conductors would connect to the motor. Or am I wrong assuming my input/outputs?
I apologize for not providing this extra bit of information from the start.
P.S. The controller instructions came with no wiring diagram...it only noted that the "blue" wire was the control wire.

Thanks in advance for your response!
Daren

socket.PNG
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Downunder35mSpringsdude

Reply 17 days ago

See! Now the controller makes a lot more sense!
The fan goes onto those pins in your image!
I then guess the controller is actually to use a standard fan on a motherboard that needs a fan speed response.
A bit more complex than what you need LOL
That then makes Yellow your 12V positive and black your gound/negative.
With that the controller should be able to provide an output to the fan connector.
With your pic as shown, the first pin from the left should be ground, the second motor positive and the last the sensing.
You only need the first two though.
I assume that connected like this you should be able to control the speed of your gearbox.