ATX connector

[MaXiZ]

Hi to all.
Are -12/-5v absolutely necessary?
Or can i eliminate them?

[AudioFreak]

Perhaps more to the point, why do you want to remove them?

[MaXiZ]

becouse obatin +3.3, +5 and +12 is so simple.
Instead for -12 and -5 i've ecountered some difficulties..
Sorry for my english! :P

[AudioFreak]

So you wish to make your own ATX power supply from the ground up?

[MaXiZ]

exactly.
+5,+12 and +3.3 are done.
But i've a lot of difficulties to obtain -5 and -12.
So i've asked if they're absolutely necessary!

[AudioFreak]

Is this for a computer? There are alot of control systems involved in an ATX power supply such as the 5VSB, PS_ON and PWR_OK. There is quite a deal more involved than just the rails...

As for the -5V and -12V lines, to meet the official specification you must include these. The question then comes down to what exactly it is you wish to power with this supply and is it capable of running without the -5V and -12V lines.

[MaXiZ]

Is this for a computer?

Yes.

There are alot of control systems involved in an ATX power supply such as the 5VSB, PS_ON and PWR_OK. There is quite a deal more involved than just the rails...

I know but i8 would like to try anyway! :P
in any case i will lose a motherboard and cpu that can value max 20€!
is it capable of running without the -5V and -12V lines.

is it capable of running without the -5V and -12V lines.

That's the problem! :P

[AudioFreak]

It will depend on the exact hardware configuration you wish to use (There is no simple yes or no answer. We need more information about the exact hardware you wish to use). Also, I made mention of those control systems because the computer will not even start if the control systems are not in place to provide the correct signals to the logic on the motherboard.

[MaXiZ]

is this an "ok" schematic?
http://www.mitedu.freeserve.co.uk/Ci...er/1230psu.htm

[DaKi][er]

-5V isn’t used anymore, most computer PSU's don’t come with it at all. It was used on the old ISA bus but that is long gone

-12V is still used but only for serial ports and also is present on the PCI slot but most PCI cards don’t use this at all, so if you don’t use the serial ports it's safe to turf as well