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ORIGINAL: Andrew
How to convert an ATX powersupply

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ORIGINAL: hands without shadows

Unless you read the design guide update carefully that method doesnt work because it doesnt refer to any sense wires besides the 3.3v sense wire (brown or light orange).

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ORIGINAL: Andrew

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ORIGINAL: hands without shadows
Unless you read the design guide update carefully that method doesnt work because it doesnt refer to any sense wires besides the 3.3v sense wire (brown or light orange).

Did you read the last paragraph in the design guide update? I suppose the assumption was that you would read the section on remote sensing carefully -- it does reference sensing on the +5v and +12v rail. I have also seen one supply with a sense wire on ground.

I've converted around 80 or so supplies and run latch and voltage level tests on well over 200. There is a lot of variation across models - some supplies will latch and hold without a preload; some will not. A few will run without reconnecting the sense wires; the majority will not. Stability under load varies considerably -- Antec and Sparkle have performed well. To cover all the bases in the conversion process places some burden on the reader to be equally diligent.

If there is mis-information in the conversion, I would appreciate knowing.

andrew

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ORIGINAL: hands without shadows

In the few psus that I have converted I have never seen a sense wire on ground, it's interesting that it's there but I see no need for it, Ill edit my write-up (again) and add that.

As far as I know all ATX power supplies require a load to function while the older AT power supplies do not, are you sure you didn't test AT ones? Please let me know so I can add that.

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ORIGINAL: GTB
Were is the battery for it?

That's not a power supply if you can't use it anywhere.

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ORIGINAL: healthyfatboy
Will an ATX Switching Power Supply work for this mod?

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ORIGINAL: Gigaah
What do you guys think of something like this? All the jumper and resistor hocus pocus wrapped into a neat package.
I made a couple for friends and myself. The unit below would be a 10amp version due to the binding posts rating, and Its only using the one yellow wire from the 20 pin connector.
This particular one is only wired for 12volts. Has an LED so you know its on. This one has no switch because we just unplugged the thing when its not in use.
I wonder if others are interested and if its worth my time to offer somethiing like this since I don't know what people would pay for it.

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ORIGINAL: 3d Marky
Amendments to the designs.

1) Why not use a 3.3 ohm ballast 10w resistor instead of a 2 ohm if you struggle to get 12v from your supply. Using 3.3 ohm means you can still use just a single 10w resistor using the case as a heatsink. Wattage will be around 8.75
I found that there is only a minimal increase of .1 - .15 of a volt between the two values.
Once you go below 3.3 ohms you must use two 10w 1ohm resistors in series (2 ohm’s) as the current will be above 13.5w and will burn out a single resistor.

2) Only bundle 2-3 wires of each colour together when soldering to the connectors. You do not need to use all the wires as stated in the tutorials as the current will never be that high. Cut off the unused wires or your end up with a mess in the case.

3) The ATX cooling fan can be very noisy so simply add a 50ohm 1/2w resistor or higher in line to the positive of the fan. This runs much quieter but still gives a reasonable air flow through the case.

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ORIGINAL: motohead400

For charging batteries with this, do you need to be concerned about the amperage? Wouldn't an adjustible amperage control be needed or something?

Or is this solely for powering a DC in - DC out charger?

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ORIGINAL: dondeaida

Well... Simply forget the resistor thing (just turn off or unplug the power supply when not in use) ATX Switching mode power supplies these days are designed so that it will not be damaged as long as there is a very very little load present and since all ATX power supplies have a fan in it, a small load is always present. This makes "max power save mode" possible in which all data in RAM is saved to harddisk and basically the computer shuts down (Some ATX supplies even shuts down its own fan and still no damage) A very small additional load should wake up from this max save mode to full power via implementations like mouse break or wake-on-lan. This means charging batteries alone should wake up ATX to full power (It may not in rare cases, explained later)

Bottom line: You do not need a resistor. And if you are a worrying type, do this (even though you do not need to do this) : Hook up the batteries BEFORE you plug in the ATX to the wall and when charging is done, unplug ATX from the wall first and then take those batteries out.

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If you still cannot live without a resistor and need a heat source in cold weather, hook it up to 5v. This is because motherboard works at 5v and it is this 5v load that brings ATX supply to full power (mouse break, wake-on-lan are all 5v based) But the fan in power supply is 5v on the first place, so basically most ATX are ever-ready and you do not need a resistor in 5v line.

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In rare cases ATX power supplies will not wake up at 12v load (A very few ATXs' can't convert 12v load into 5v load) In this case, you do need a 5v load but a small one will do (resitor is not a good idea anyways since it creates lot of heat. use a led or a fan instead. CPU fans are 5v)