PC power with 24v


C

Coder

I want to know if exist one PC Power Supply with these
output +5V, +12V, +24V.

Thank you.

S.L.
 
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M

Mike T.

Coder said:
I want to know if exist one PC Power Supply with these
output +5V, +12V, +24V.

Thank you.

S.L.
Nearly All of them do, if your +24V requirement is about 10W or less. They
all have the +5V listed in the specs, and they all have the +12V listed in
the specs (often more than once, like +12V1, +12V2). You won't see +24V
listed, but you can power something that needs +24V. See, there's also
a -12V rail. So use the -12V rail as "ground", and you've got a voltage
source that is +24V. Most components won't care where "ground" is as long
as there is proper voltage applied in relation to ground. You could use a
floating ground that is "floating" around -12V. -Dave
 
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P

Paul

Coder said:
I want to know if exist one PC Power Supply with these
output +5V, +12V, +24V.

Thank you.

S.L.
Apple Computer has a series of computers with what is called
ADC video port, and the power supply in those computers
has +5V, +12V, and +25V (at 4 amps) or so. Obtaining a
power supply for one of those Apple computers, would solve
your problem. The 25V supply is intended to be regulated
further by the monitor, into lower voltages suitable for
running circuits inside the monitor.

http://developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G4/PowerMacG4_16Jan01/3Input-Output/Apple_Display_Connector.html

http://en.wikipedia.org/wiki/Apple_Display_Connector

PC power supplies are defined by standards. The standards
information is available on www.formfactors.org .

Once you put that 24V output on the supply, it is no longer
compliant to standards. It would be a custom power supply,
by definition.

Ways to solve your problem:

1) Provide a 24V wall wart to your customers. Place a
female plug on a PCI slot cover, then plug the wall
wart into the PCI slot cover. That would allow passing
24V from an external source, inside your computer case.

2) Contact one of the many manufacturers of PC power supplies.
Apple has been known to use Acbel as a supplier. There
are plenty of others who will manufacture custom supplies
for a price. ( http://www.acbel.com.tw/ )

3) If the amount of current required is small, perhaps
a DC-DC converter, could convert 12V to 24V inside the
computer. This is viable, as long as the 12V rail has
sufficient ampere capacity to drive the DC-DC converter,
plus the other loads in the computer. For example, if I
select 12V input, 24V output, 25W output power (about 1 amp),
they list a price of $99 for a module. The module should
have a suitable heatsink, as DC-DC conversion is not
100% efficient. Basically, the module converts 12V@2A to
24V@1A. If the module is 90% efficient, then it would be
closer to 12V@2.2A to 24V@1A plus 2.4W of heat.

http://vicorwebapps.vicorpower.com/upc/FirstGenDCDCInit?vInSeq=10

If you expect a lot of amps at 24V, then DC-DC conversion
from 12V will not be a viable solution.

Note that the DC-DC converter has a startup time, so the
24V will show up roughly 35-50 milliseconds after the 12V
is stable.

HTH,
Paul
 

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