Coputer to Lab power supply conversion
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Posted by on May 28, 2008, 5:21 pm
Please log in for more thread options formal training. I have a pretty good understanding of components but know basically nothing about systems as a whole. I got my hands on an old computer supply and read about converting them for use as a lab power supply. The directions said the poower supply needs to be loaded to run, For their 450 watt power supply a 10 ohm 10 watt resistor was used. My power supply is only a 90 watt, 10 ohms sounds like overkill. I have a 250 ohm power resistor laying around. by my calculations this will pull about 45 milliamps at 12 volts. Does this sound like enough to load my 90 watt power supply? if not how many amps will it take? thanks in advance! | ||||||||||||||||
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Posted by Lord Garth on May 28, 2008, 5:52 pm
Please log in for more thread options Is that an old 90 watt PCXT power supply???? Those needed a load similar to an ST506 hard drive or an amp or so on the 12 volt line. In any case, you don't say what the current capability is of the 12 volt output. 90 watts is likely the total supply capability inclusive of all its outputs. | ||||||||||||||||
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Posted by on May 29, 2008, 1:12 am
Please log in for more thread options >
> > > Hey everybody. I am a hobbyist in the field of electronics with no
> > formal training. I have a pretty good understanding of components but > > know basically nothing about systems as a whole. I got my hands on an > > old computer supply and read about converting them for use as a lab > > power supply. The directions said the poower supply needs to be loaded > > to run, For their 450 watt power supply a 10 ohm 10 watt resistor was > > used. My power supply is only a 90 watt, 10 ohms sounds like overkill. > > I have a 250 ohm power resistor laying around. by my calculations this > > will pull about 45 milliamps at 12 volts. Does this sound like enough > > to load my 90 watt power supply? if not how many amps will it take? > > thanks in advance! >
r
> Is that an old 90 watt PCXT power supply???? =A0Those needed a load simila= > to an ST506 hard drive or an amp or so on the 12 volt line. =A0In any case=
,
> you
s is
> don't say what the current capability is of the 12 volt output. =A090 watt= > likely
> the total supply capability inclusive of all its outputs. Sorry, i'm not sure what kind of ower supply it is, all i can tell you is the model number sfx-1209f. and yes, 90 watts is the overall out put. 1.5 amps are availble on the 12 volt channel. here is another though, since i only plan on using the 12v channel would it be a better idea to load the 5 volt channel? Thinking out loud.... I'll probablly go with jamies ide and just try it. obviously I'll have to bost the resistance since less current is going to be pulled at 5v. perhaps some led's? i'll ned a few of em to pull enough amperage... | ||||||||||||||||
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Posted by Lord Garth on May 29, 2008, 7:05 pm
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>
<snip> >Sorry, i'm not sure what kind of ower supply it is, all i can tell you >is the model number sfx-1209f. and yes, 90 watts is the overall out >put. 1.5 amps are availble on the 12 volt channel. here is another >though, since i only plan on using the 12v channel would it be a >better idea to load the 5 volt channel? Thinking out loud.... I'll >probablly go with jamies ide and just try it. obviously I'll have to >bost the resistance since less current is going to be pulled at 5v. >perhaps some led's? i'll ned a few of em to pull enough amperage... As a hobbyist, you should build your first power supply! At 1.5A, you can easily get this with a either a linear regulator or you can opt for a switching regulator. In either case, the parts count is low. A quick google search should get you some part numbers from which to start. If you still wish to use the computer power supply, load it with an incandescent bulb. A 6 volt bulb on the 5 volt output is not a problem. | ||||||||||||||||
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Posted by on June 7, 2008, 4:59 am
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> As a hobbyist, you should build your first power supply! =A0At 1.5A,
> you can easily get this with a either a linear regulator or you can opt > for a switching regulator. =A0In either case, the parts count is low. =A0A= > quick google search should get you some part numbers from which
> to start. Sounds great, there are just a few problems. I'm 17 and my parents are not hobbyist. Anything that plugs into the wall terrifies them. I'm already going to have to plug this "proffessionaly" made power supply into a surge protector so I have a remote switch of sorts. The second I opened the case to get at the PCB my parents swore they'd never let me plug it in. It's funny really. I'd feel so much safer plugging in my own creation than some mass produced peice of junk from China, which they do on a daily basis. > If you still wish to use the computer power supply, load it with an
> incandescent bulb. =A0A 6 volt bulb on the 5 volt output is not a problem.= sounds good. I'll pick one up from radio shack or something. Thanks for the help! | ||||||||||||||||
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> formal training. I have a pretty good understanding of components but
> know basically nothing about systems as a whole. I got my hands on an
> old computer supply and read about converting them for use as a lab
> power supply. The directions said the poower supply needs to be loaded
> to run, For their 450 watt power supply a 10 ohm 10 watt resistor was
> used. My power supply is only a 90 watt, 10 ohms sounds like overkill.
> I have a 250 ohm power resistor laying around. by my calculations this
> will pull about 45 milliamps at 12 volts. Does this sound like enough
> to load my 90 watt power supply? if not how many amps will it take?
> thanks in advance!