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Help with 12v fan system

Bretto86

Jul 29, 2023
1
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Jul 29, 2023
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Hi all,

Very new here (just stumbled upon this website today while researching a small project).
I hope that what I'm asking is relevant to this forum & also in the right area but please forgive & advise if it is not...

I will do my best to explain my needs & planned outcome but please feel free to ask any questions!

I am fitting out a canopy/aluminium box on the back of a ute (truck for you Americans & otherwise - I'm in Australia, hence ute) for the purpose of camping & travel. There is an existing 12v fridge in the canopy.
I plan to have at least 2 x 12v, 120 or 140mm fans drawing outside air into the canopy & at least 3 x 12v, 120 or 140mm fans pushing hot air out of the canopy.
In addition to this the 12v fridge has a 120mm fan blowing over the compressor & I plan to add a 12v, 100mm fan INSIDE the fridge to circulate air (with the fridge I have this is a recognised modification with proven results).
Where it all gets a little tricky is that I am stubborn & somewhat set on the components I want to use, be it due to performance, aesthetics, reputation & reliability or otherwise.
I'm here to ask you good people if I can actually make it all work...

I want the fans to work on a PWM system, ramping RPM up or down as required.
For this I would like to use an AC Infinity Controller 69 which allows me to monitor 4 different temperatures & control 4 different "zones" accordingly. This is overkill for my needs, I likely only need two (fridge temp & canopy temp) but the extra ability won't hurt should a future project pop up.
The problem is that I want the ability to move a LOT of air (more for the canopy intake & exhaust fans) so I plan to use 12v fans, namely Noctua NF-A14 12v 140mm 3000rpm industrial series fans for the 6x 140mm fans & a NF-A9 PWM for inside the fridge.
Each of these 140mm fans is around 7w while the controller has a max rating of around 10w from what I can see.
This is likely a stupid question but can the controllers output be used as a signal to power a more capable form of powering these fans?
This would obviously mean additional cost & work but will get me the results i want.

I look forward to discussing
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
Given the controller only supports a maximum of 10W (direct drive) you will have to buffer the PWM signal.

This is easily achieved with MOSFETs where you apply the PWM signal to the gate of the MOSFET and use the source/drain circuit to control the load - which can be 'anything' depending on the parameters of the chosen MOSFET.

This link; https://www.instructables.com/How-to-Control-a-MOSFET-With-Arduino-PWM/ shows an Arduino PWM signal being buffered but if you just think of the PWM signal as coming from your controller the rest of it is 'as-is'.
 

Bluejets

Oct 5, 2014
6,918
Joined
Oct 5, 2014
Messages
6,918
I am fitting out a canopy/aluminium box on the back of a ute
I imagine all this cooling requirement is for when the vehicle is stationary.................???
I can see the "possible" requirement for giving the frig compressor some air on the compression side but the need to "suck in fresh air" seems questionable.
Simply removing the hot air should be sufficient, forget the pwm , simply turn on and off when required perhaps by a basic thermostat arrangement.
 
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