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fan power on a 12v led power supply

Posted by flydeprutten 
fan power on a 12v led power supply
May 16, 2018 09:26AM
Hi,

I have a question about power supplies.

I just bought a 12v LED power supply for my printer, but as the fan was incredibly loud, I replaced it with a 60mm noctua fan I had lying around.

The power supply is 360 w, but at the moment I do not have a heatbed, and therefore, it is also not under full load right now.

After installing my new fan, I thought it was still loud, and the fan was actually louder than usual. Therefore, I measured the voltages that the fan receives from the power supply, and it changed depending on the amount of watt the printer pulled.

When the printer was idle, the fan got about 10 volts. When the printer warmed the hotend, and it pulled the most watts, it got about 17 volts, and when it had reached the temperature and only had to maintain it, volts fell to between 11 and 13.

Under all this, the printer was constantly receiving 12 volts.

Is this normal for such a power supply. I'm a little nervous about my noctua fan if it already gets 17 volts at this small load. What will it not get at full load. Is there anyone who can explain this?
Re: fan power on a 12v led power supply
May 16, 2018 09:34AM
My experience with those cheapo "LED" power supplies is that if the fan turns on, the supply is about to die. If the voltage is dropping and the fan is kicking on you're definitely overloading the supply.

Look into a MeanWell power supply- not the fake MeanWells that littler ebay, but a real one that has safety certifications. They have protective circuits that actually keep the power supply from dying in the event of short, overloads, overheating, etc. They cost just a few $ more than the junk supplies.

If your controller board (and heaters) can handle 24V, use 24V, not 12V.

I have used LRS-200-24 fanless 24V power supplies in 2 printers and they're bullet proof. No fan, no noise.


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: fan power on a 12v led power supply
May 16, 2018 09:35AM
Yes, its a crappy supply without a temperature sensor, so the fan is always on and just reponds to load a little.

See [www.youtube.com] for how to add in the sensor back in.

Edited 1 time(s). Last edit at 05/16/2018 09:36AM by Dust.
Re: fan power on a 12v led power supply
May 16, 2018 09:36AM
A 12 volt LED power supply should never under any situation reach 17 volts across the fan.
I would also measure voltage on the power to the controller when the fan voltage is 17 volts, if this voltage is 17 volts you are risking burning up the controller.

Edited 1 time(s). Last edit at 05/16/2018 09:41AM by Roberts_Clif.
Re: fan power on a 12v led power supply
May 16, 2018 09:37AM
17 does sound a lot high...
Re: fan power on a 12v led power supply
May 16, 2018 09:43AM
Quote
Dust
Yes, its a crappy supply without a temperature sensor, so the fan is always on and just reponds to load a little.

See [www.youtube.com] for how to add in the sensor back in.

I have seen the guides, but it does not seem to be the same type of power supply as mine. There is no connector for mounting a thermal relay.
Re: fan power on a 12v led power supply
May 16, 2018 09:48AM
Quote
the_digital_dentist
My experience with those cheapo "LED" power supplies is that if the fan turns on, the supply is about to die. If the voltage is dropping and the fan is kicking on you're definitely overloading the supply.

The power supply constantly supplies 12 volts to the printer. This is not the problem, and there is no thermal relay in the supply, which means that the fan always runs.

Quote
the_digital_dentist
Look into a MeanWell power supply- not the fake MeanWells that littler ebay, but a real one that has safety certifications. They have protective circuits that actually keep the power supply from dying in the event of short, overloads, overheating, etc. They cost just a few $ more than the junk supplies.

If your controller board (and heaters) can handle 24V, use 24V, not 12V.

I have used LRS-200-24 fanless 24V power supplies in 2 printers and they're bullet proof. No fan, no noise.

Unfortunately, my controller can not run on 24v.
Re: fan power on a 12v led power supply
May 16, 2018 09:50AM
That PSU obviously does have a temperature sensor for the fan, otherwise the fan voltage wouldn't vary with load the way it does. But it appears to be designed for use with an 18V fan, not a 12V fan. Are there any markings on the original fan that indicate its operating voltage?



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: fan power on a 12v led power supply
May 16, 2018 09:58AM
Quote
dc42
That PSU obviously does have a temperature sensor for the fan, otherwise the fan voltage wouldn't vary with load the way it does. But it appears to be designed for use with an 18V fan, not a 12V fan. Are there any markings on the original fan that indicate its operating voltage?

Yes, it says 14 volts.

By the way, if I use Noctuas low noise adapter, the volts are higher before adapter, compared to if the fan was put directly to the fan header. But of course lower after.

Edited 2 time(s). Last edit at 05/16/2018 10:01AM by flydeprutten.
Re: fan power on a 12v led power supply
May 16, 2018 10:46AM
Most LED power supplies have a 12 Volt adjustment potentiometer. As shown in the Image below.



This should be adjusted to 12 volt. Higher voltages will allow ripple voltage under higher loads on the supply, this will in turn cause you nothing but greef.
Making you chase noise spikes causing many 3D Printer ghosts effects, the noise spikes on the controller voltage will cause you a most unpleasant 3D Printer experience.

My 12 volt 360 watt supply came pre-adjusted to 13.8 volts it took me what seemed like forever and drug out my dusty old oscilloscope to track down this problem.

Edited 5 time(s). Last edit at 05/16/2018 11:03AM by Roberts_Clif.
Re: fan power on a 12v led power supply
May 16, 2018 11:00AM
Quote
Roberts_Clif
Most LED power supplies have a 12 Volt adjustment potentiometer. As shown in the Image below.

This should be adjusted to 12 volt. Higher voltages will allow ripple voltage under higher loads on the supply, this will in turn cause you nothing but greef.
Making you chase noise spikes causing many 3D Printer ghosts effects, the noise spikes on the controller voltage will cause you a most unpleasant 3D Printer experience.

My 12 volt 360 watt supply came pre-adjusted to 13.8 volts it took me what seemed forever and a oscilloscope to track down this problem.

Under all my test of the fan, I also measured the output for my printer. This output was constant 12 volts.
Re: fan power on a 12v led power supply
May 16, 2018 12:27PM
If I do not care that the fan is running all the time, can I then just connect it directly to the normal 12v output, and forget about the internal fan header?
Re: fan power on a 12v led power supply
May 16, 2018 01:08PM
I personally connected My fans to the Part Duct fan.

Decided that the only time needed the Controller cooled was when 3D printing, and the model Duct fans is running at 40 - 60% when 3D Printing.
This solved my delima, this maybe a solution for yours as well.

Another thought is a simple 0-12volt variable voltages regulator LM317, use this as a fan control circuit.
All parts can be mounted on the Ohmite Potentiometer. ( I only use Ohmite Potentiometers because they last a long time)



Edited 1 time(s). Last edit at 05/16/2018 01:09PM by Roberts_Clif.
Re: fan power on a 12v led power supply
May 16, 2018 01:50PM
Hook the fan up to the 12v outputs with a mechanical thermostat:

[www.amazon.co.uk]

In fact, this is the same as the one used in most cheap power supplies already.....
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