My nephew is making himself a custom case for a PC. On one end he has a 12V car radiator fan to use for cooling. We are looking for a power supply to run it off 240Vac, but the packaging says that the fan uses about 11A max. What is the best way to power this fan? It will be using a separate power supply to the PC parts. Would it be best to somehow drop the amps used by slowing the fan? Would another fan be better for this purpose? We are basicly looking for a cheap way out.
Thanks
Dont forget the earplugs !! Use a lower voltage supply to reduce current and noise, try 9v for a start but it should run with less than that. If it will get away on 5v you could use an old PC psu.
-- Cheers ......... Rheilly P Where theres a will, I want to be in it.
If he really really really wants to do it a dunny exhaust fan might be better - quieter & probably cheaper too. The bearings in them don't last too long if ceiling mounted ones are run on their sides. I think they start at around $15.
Get a switched-mode powersupply designed to operate CB radios etc... the warehouse has some for fairly cheap. (also cheap inverters) ISTR the warehouse PSUs were rated 8A (so a smaller fan might be good) and 13.8V (but thats normal in a "12V" automobile)
be aware that cars do about 200000km before things really start failing. that's equivalent to about 3-6 months continuous running time and also cars don't run the fan continuously.
OTOH a second compuuter powersupply could probably be convinced provide 12V for your fan.
with a fan that size you could drill holes in the bottom and have a hovercraft :)
Bye. Jasen
What about using the 12V rail on an old PC supply? You might have to pick through a few,in order to get a high enough current rating on the 12V rail..most are under 10A on the 12V rail,some are more... Cheap and easy,if you can find one that's suitable in the scrap heap :) You can also run the fan on the 7V output (between teh +5 and +12V rails) to get it to run slower,and thus quieter. (a common "trick" for the internal case fans,to make them a bit more quiet.)
It works for some people, not all supplies will give full power on +12 without a load on +5
most 200W supplies will give 10A, dunno what current it takes to start a "11A" motor though.
if the supply is otherwise unloaded you need a load between the 5V an 0V that exceeds current draw of the load between the 12V and 5V -
it may be better to add a series resistor, or to beef-up the -5V diodes and run the fan off 10V
-- Bye. Jasen
Excuse my ignorance, but why would one want a car radiator fan that draws 11A to cool a PC?? Last I checked a PC did not generate anywhere near the heat of a car.
He is building a custom case, basicly a long octagon tube, and the fan fits perfectly on the base of it. The fan is not so much there for the cooling purpose, it is more for looks. That's why I asked about slowing it down and making it quieter.
Thanks for the other suggestions, I will probably have to try some and see how it all works out.
Grenge
Just thinking out loud, but would it be possible to wire a knob in with the fan, like a variable resistor, that would control the speed of the fan? Mainly just to slow it down or speed it up? Would this just be a variable resistor or something else a bit more complex?
Thanks Grenge
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