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Jul 23, 2008, 09:59 PM
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Using PC power supplies for chargers?


Does anyone have any experience/hints/resources/links when it comes to converting and using a PC power supply unit into a 12v DC power supply for a charger?

My main concern in using an ATX power supply is how do I tell it to always be on? As far as I know, with ATX PS, it's always on and when it's off, it's rather in a soft-off mode. So if I just turn it on without connecting to a motherboard/power button, it might not actually supply the 12V and so on.

Reason I'm asking is because I saw a very cheap generic 430 watt PSU in a computer store for $20. In the specs, it said it only had one +12V lead which supported up to 24 amps.

12V * 24 amps = 288 Watt, which should be enough for my future 180W charger (iCharger 106B), right?

Thanks!
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Jul 23, 2008, 10:23 PM
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ebill3's Avatar
Lots of folks use ATX supplies for charger supplies. Lots of threads - here is one that should answer your questions.

Bill
Jul 23, 2008, 10:32 PM
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Jul 23, 2008, 10:48 PM

Works for me


I have messed with computers for along time, before I toss them I always pull the power supplies.
There are guides on the web (an on this forum) about how to do it exactly right, which involves some kind of resistor on the 5v lines a proper switch and a bunch of other details.

I simply left the switch on and gathered all the ground black and all the 12v (yellow) wires in to there own separate group. The newer ATX that work with the Pentium 4 Motherboards have some additional wires, 12v I think for the processor and sometimes one for the graphics card. You can find lists online for whatever the standard labels for those wires should be. On that list you should find the two 'power good' wires that need to be connected for the PS to be on.

The one thing I would mention is I would be careful, there are a lot of amps in those Power supplies. I would feel a bit nervous holding the metal case of the PS when I pushed the power cord into the back.
Jul 24, 2008, 12:30 AM
Registered User
I fried 2 ATX powering FMA Balance Pro 200w+. I finally settle with IBM 235 eSeries from fleabay. An used 360w (12v & 30 amp) cost $22 shipped. I just need to add a small jumper.
Jul 25, 2008, 10:09 AM
The Low-wing Super Cub
grubbyjeans's Avatar
Quote:
Originally Posted by shurcooL
Does anyone have any experience/hints/resources/links when it comes to converting and using a PC power supply unit into a 12v DC power supply for a charger?

My main concern in using an ATX power supply is how do I tell it to always be on? As far as I know, with ATX PS, it's always on and when it's off, it's rather in a soft-off mode. So if I just turn it on without connecting to a motherboard/power button, it might not actually supply the 12V and so on.

Reason I'm asking is because I saw a very cheap generic 430 watt PSU in a computer store for $20. In the specs, it said it only had one +12V lead which supported up to 24 amps.

12V * 24 amps = 288 Watt, which should be enough for my future 180W charger (iCharger 106B), right?

Thanks!
Here is the link to the 235 PS. I just received two of them.
Jul 25, 2008, 12:08 PM
Registered User
Quote:
Originally Posted by grubbyjeans
On that IBM server power supply you linked, does it require a load on the 5v rail to make the 12v rail output a voltage around 12v? On the PC power supplies I have converted, the 12v rail's voltage always seems to hover a bit above 11v when charging, even with a resistor on the 5v rail. On a lot of chargers 11v on the input will work but some a picky.
Jul 25, 2008, 12:13 PM
Registered User
No. All you need is a little jumper and a computer power cord. everydayflyer has a picture. Search for it.
Jul 25, 2008, 12:44 PM
The Low-wing Super Cub
grubbyjeans's Avatar
Here's the link

See also: post 31 in this thread for another pic.
Jul 25, 2008, 01:44 PM
Registered User
On some of the power supplies, you have to load the 5 volt line in order to have the proper output on the 12 volt line(s). On many of them, the load on the 5 volts is what causes the regulation of all the voltages. Use a power resistor, a 5 ohm 10 to 20 watt (properly tied to a heat sink) will do the job very well. If you want a power on indication, just put an LED in series with about 220 ohm 1/2 watt resistor across the 5 volt bus as well. If the LED is lit, the power is on.


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