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Science Forum Index » Electronics - Basics Forum » Coputer to Lab power supply conversion...
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 Posted: Wed May 28, 2008 11:21 am |
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Guest
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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! |
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| Lord Garth... |
| Posted: Wed May 28, 2008 4:52 pm |
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<ngdbud at (no spam) gmail.com> wrote in message
news:f90b4044-a9b2-4922-baa1-6002c0794b0c at (no spam) 34g2000hsh.googlegroups.com...
Quote: 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!
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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| Jamie... |
| Posted: Wed May 28, 2008 5:02 pm |
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Guest
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ngdbud at (no spam) gmail.com wrote:
Quote: 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!
YOu need to try it..
I would say most likely it'll work.
Some people put a 12 incandescent lamp on the circuit so that it can
be used for both load and indication!
http://webpages.charter.net/jamie_5" |
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| Posted: Wed May 28, 2008 7:12 pm |
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Guest
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On May 28, 2:52 pm, "Lord Garth" <lga... at (no spam) tantalus.net> wrote:
Quote: ngd... at (no spam) gmail.com> wrote in message
news:f90b4044-a9b2-4922-baa1-6002c0794b0c at (no spam) 34g2000hsh.googlegroups.com...
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!
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.
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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| Lord Garth... |
| Posted: Thu May 29, 2008 6:05 pm |
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Guest
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<ngdbud at (no spam) gmail.com> wrote in message
news:60f7c5e0-3872-419f-9980-00fee42a0885 at (no spam) s50g2000hsb.googlegroups.com...
On May 28, 2:52 pm, "Lord Garth" <lga... at (no spam) tantalus.net> wrote:
Quote: ngd... at (no spam) gmail.com> wrote in message
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: Fri Jun 06, 2008 10:59 pm |
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Guest
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Quote: 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.
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.
Quote: 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.
sounds good. I'll pick one up from radio shack or something. Thanks
for the help! |
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| Posted: Mon Jun 09, 2008 12:31 pm |
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Guest
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Thanks Nick. BTW, good name  . There was a lot of great information
there. I'm going to see if i can find some 6v bulbs this week and try
it out. |
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