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View Full Version : ATX power supply - load resistor - do I need one ?



rckeith
18-08-2010, 12:32 PM
Hi

I'm using 2 Dell power supplies to provide 24 volts and found lots of info on the net on how to do this. The only thing some say you need a load resistor and other say just bridge black and green. I've seen some sites suggesting a 12 V car bulb across the +5Volt supply is enough. The Dell power supplies I'm using are from GX270 and are 20 pin on the motherboard connector.

Would the driver board put enough load or do I just not need a load resistor.

Thanks

Keith

irving2008
18-08-2010, 12:51 PM
The issue is that some ATX supplies power down the +12v rail if there is no load on the +5. The simplest way is to try it and see... if the 12v is rock solid without a load then fine, if not, try a car bulb on the +5 rail as suggested.

danielbriggs
18-08-2010, 01:36 PM
When I've converted ATX PSU's in the past (hard wired jobbys) I've stuck a 10 ohm, 5-10W resistors (those heatsinked ones with screw down tabs) on the 5V rail, and screwed it inside the case.

http://images.productserve.com/preview/1799/37898205.jpg

Also hard wire the green wire to the GND (black)


If you want a quick way to test, just stick an old HDD on one of the plugs.

rckeith
18-08-2010, 03:55 PM
Hi Daniel

do you know of a supplier, I've looked on maplins but can't seem to find any

keith

danielbriggs
18-08-2010, 04:21 PM
Something like this if you live near an RS shop:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0159900

Or this (closest match on eBay) with postage:
http://cgi.ebay.co.uk/1-x-10R-25W-Aluminium-clad-wirewound-Power-resistor-/130368440674?pt=UK_BOI_Electrical_Components_Suppl ies_ET

Ta,
Dan :)