computer power supply

S

Sleepy-Tom

Guest
I tested the power supplies at work and found some had the -5v line not
working.
Ive put these into systems and cant notice any difference between the
ones with the -5v and the ones without.
What is the -5v used for?
 
Sleepy-Tom wrote:
I tested the power supplies at work and found some had the -5v line not
working.
Ive put these into systems and cant notice any difference between the
ones with the -5v and the ones without.
What is the -5v used for?
Click to expand...

Most systems don't use it anymore. If it is used, it will be in an
analog circuit, like the sound card. It was used for some of the early
memory in the PC & XT, and has been carried over for 'Backward
Compatibility'.


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"Sleepy-Tom" <DontSpam@ontheinter.net> wrote in message
news:48cbd78c$0$31802$afc38c87@news.optusnet.com.au...
I tested the power supplies at work and found some had the -5v line not
working.
Ive put these into systems and cant notice any difference between the
ones with the -5v and the ones without.
What is the -5v used for?
Click to expand...
RS232 communications, for one.
 
On Sun, 14 Sep 2008 17:07:02 -0400, "Charles"
<charlesschuler@comcast.net> put finger to keyboard and composed:

"Sleepy-Tom" <DontSpam@ontheinter.net> wrote in message
news:48cbd78c$0$31802$afc38c87@news.optusnet.com.au...
I tested the power supplies at work and found some had the -5v line not
working.
Ive put these into systems and cant notice any difference between the
ones with the -5v and the ones without.
What is the -5v used for?

RS232 communications, for one.
Click to expand...
That requires +/-12V. Some RS232 chips can generate both rails from
the +5V supply via their internal charge pumps.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
On Sun, 14 Sep 2008 01:08:57 +1000, Sleepy-Tom
<DontSpam@ontheinter.net> put finger to keyboard and composed:

I tested the power supplies at work and found some had the -5v line not
working.
Ive put these into systems and cant notice any difference between the
ones with the -5v and the ones without.
What is the -5v used for?
Click to expand...
The PCI bus does not use -5V:
http://pinouts.ru/Slots/PCI_pinout.shtml

I believe the -5V rail could have been used by ISA data acquisition
cards. Some early DRAMs and EPROMs also required it.

http://pinouts.ru/Slots/ISA_pinout.shtml

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:2OWdncBmUojXflbVnZ2dnUVZ_sninZ2d@earthlink.com...

Most systems don't use it anymore. If it is used, it will be in an
analog circuit, like the sound card. It was used for some of the early
memory in the PC & XT, and has been carried over for 'Backward
Compatibility'.
Click to expand...
Ah, you're full of shit.
 
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