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Posted: Sun Jan 01, 2006 4:21 am Post subject: Re: ATX Power Supplies |
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I am pretty sure that all ATX switching power supplies require a load to operate. Which voltage(s) require a load might be different on different supplies. It depends on the design. Switching power supplies are generally good for efficiency. However a computer power supply is not in my opinion as good a supply as you might find in other equipment. Depending on what equipment we're talking about. They have a certain point that they are most efficient. I think typically that is at about the 70% of max load point. Typically the efficiecy is bad at low loads. But it does not matter particularly. If the power supply is shorted then it's supposed to shut down. Switching power supplies have it in their design that they won't switch if their load is too high. They depend on resonance to switch and a high load changes the resonance to a point where it does not switch. So the shut down with a short is self fullfilling. You do need a minimum load to make the power supply work. Again because of the design it needs some load to switch. Usually it's the +5 that needs a load. Typically in my experience of non-atx switching power supplies the various voltages are interdependant typically through a commonly wound switching transformer. A schematic would help you see the interaction among the voltages just for fun. Startup and holdup time - They are not as good for holdup time as some supplies that I've worked with. Typically when the power goes off the power is gone within 17ms. Some supplies hold up for seconds or 200x longer. Just try your stereo at home. Turn it off and see how long it operates. Startup time is pretty good I think. No particular problems that I see. One consideration since you mention cheap and cool is that an ATX supply NEEDS the fan to operate or it will die. Some supplies don't need a fan. Open frame supplies don't need fans. Some are very cheap on the surplus market. Power-One is one mfg who makes them. I have a bunch of them with various multiple (2) voltages that I got for $10 ea. They are linear instead of switching. Typically linear means better regulation. And faster response to changing loads. You didn't mention what the PS is for. We're all curious. Andre |
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Posted: Thu Dec 15, 2005 4:14 am Post subject: ATX Power Supplies |
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Many thanks for the information and is very useful. |
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didgeman |
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Dutchy |
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Posted: Tue Nov 15, 2005 1:01 pm Post subject: ATX Power Supplies |
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I am considering installing an ATX power supply in alternative equipment as they run fairly cool with a fan aswell as being cheap. The supplies required would be automatic switching 110/240 a.c input and outputs of +12V, -12V and +5V only are required (the -5V will not be used). The question would be really How do these perform wouthout load and short circuit? They would also reqire to be enabled at all times as the equipment would have external mains switched. At the moment this is just an Idea and have not really looked into these supplies in any detail All replies very much appreciated. Many Thanks |
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