how to power 4pin without computer?

Thread Starter


Joined Mar 10, 2021
I plan to make 3d printer enclosure. there should be a fan, which have 4 pin connector.
How can I power the fan without computer, direct from wall socket?
If connect to 12V power adapter with GND and +12V of 4pin, It would work?


Joined Sep 17, 2013
Clearly the 24V supply goes to the yellow and black wires. Presumably a ground-referenced PWM signal applied to the blue wire controls the fan speed and the green wire provides an output voltage proportional to rpm achieved.
What are the specified voltage limits for the PWM signal? Can you use a DC voltage (0-5V range?) in lieu of PWM?
tHIS Tells us how it works, but it doesn;t tell us what characteristics of the signal is required.

Probably a constant 5V will work applied to the PWM pin.

This describes the signals needed.

You need to find out the power requirements for 24V. You need a tiny bit of 5V power. You could add, like a 100 ohm resistor in series with the 5V supply to act as fuse. If you have an extra port on your computer, you could possibly use it to control the ON/OFF of the fan.

The simplest is a USB phone charger. That will supply 5V at 100 mA and they are everywhere.

Two meanwell DIN rail mounted power supplies could also work. e.g. The case

Din Rail DC-DC converters are just more expensive:

There are lots of PWM modules out there that could also be used to give your variable speed.

Take a look at for DIN rail modules and a case etc. DIN rail is the control engineer's erector set.

Here is a complex control panel

In general, you attach pieces of TS32 rail (aluminum, steel, slotted) to an enclosure with a inner thick aluminum backplate.
and create channels for wire with wireduct.

"Terminals" start with a end bracket to provide an immobile end.
Then many terminals generally missing a side.
Partition plates can group off terminals or end covers.
A cover is the same size as a terminal, the partition plate larger.
Finally you finis with another end bracket.

ground terminals don't need partition plates or covers.
You can have multiple levels and there are buss bar jumpers.
The partition plates and the end covers have to match the series.

This shows a lot of what's available except their minimum quantities are too high. Look at too.

Traditionally, the control panels are freestanding (rack) or on the wall with a flanged case. I built a fair number in rack cases with chassis slides without a backing panel. I probably used flat head screws.

Two comments:
Power should enter at the top with an immediate way of disconnection. e.g. breaker/fuse
If you have a connector or conduit entering the box, the first thing you should do is break it out.
e.g. Run the wires to a terminal strip.

One box, I built had almost nothing in it. It basically collected the building related panics, strobes, gas detection, velocity detection etc.

So, it consisted of a 37 pin CPC connector going to 37 terminals. It eventually got AC power and a 24 VDC power supply.
A large conduit went above the ceiling connected to a large junction box to strain relief the wires ran over the ceiling.
The 24V power supply ran the hood velocity detector which effectively belonged to the "building" and not the experiment.
It contained one indicator.

I made an unwritten rule, that because multiple panels were connected from multiple rooms. I would not allow a direct connection to 24VDC from another room to a pilot lamp on the door. It had to go to a relay first. The door lamp would be powered from the 24VPS in the cabinet where the lamp was. That way, I knew where the power was and where it was coming from and I could generally work on one panel without affecting the others. BTW, this was a safety system that had to work.
it should have contained a velocity readout like the system I designed, but management was cheap. It should have latched the alarms, but management was cheap. So, you could not tell if the sensor was dirty or position the sensor after a clean and sometimes you had no idea what caused the system to shut down.

What actually happened is that "they" wired their rack-based shutdown system, so you could not disconnect and troubleshoot it. It broke and that's how I got my absolute required changes. I think wires just dangled from the ceiling connected to barrier strips on a free-standing 19" rack, with no way to remove the case or pull it out via slides to repair.


Joined Sep 17, 2013
According to the motor spec in that Noctua link, the PWM input has a built-in pull-up resistor and 'the fans operate at full rated speed if there is no PWM input signal'. The PWM input max voltage is +5V. The RPM output is a pulsed signal, 2 pulses per rev.