DIY DC power supply???

**Marsupial** · 02-27-2004, 05:15 PM

ATX provides 3.3, 5, 12 and have a powerdown connection on the motherboard - it actually controlls itself on/off. Some 5V are still on when the system is off.

**Rob Withey** · 02-27-2004, 07:08 PM

Originally Posted by ElPiloto

The only difference between AT and ATX power supplies are the connectors on the motherboard. So, just use ATX connectors instead of AT.

Complete rubbish.

5v standby.
3.3v
power good.
motherboard controlling the power on.

I suggest you read the ATX spec. The timings can be critical as the recent(ish) Epia/Sproggy experiences show.

**Ricky327** · 02-27-2004, 10:48 PM

Ricky: how do you convert it to ATX?

As been said...follow the ATX requirement. Personally I havent done it, not exactly straight forward but it can be done.

Its probably easier to base your design using the sproggy. Rip out the sproggys regulator and replace it with this AT PSU regulator.

Hope that make sense

**none** · 02-28-2004, 01:44 PM

Originally Posted by Ricky327

Its probably easier to base your design using the sproggy. Rip out the sproggys regulator and replace it with this AT PSU regulator.

How is this one superior to the Sproggy? Why do that? Just curious.

**Ricky327** · 02-28-2004, 04:33 PM

Probably not better but not man said >>> Good for people to have options ya know?

Also efficiency perhaps?

Check the datasheet :

http://www.onsemi.com/pub/Collateral/MC34167-D.PDF

Stepup/stepdown is achieved with a single coil and a mosfet...easier to find components than a transformer. While the sproggy derives its 12V from the regulated 5V by steping up...not that efficient?

**netman86** · 01-22-2007, 10:34 AM

at.... 12V, 5V

1tx... 12v, -12v, 5v, -5v, 3.3v.... im sure im missing a few. As well as the power switch line and whatnot.

IIRC most computers these days pull the voltage for the ram from the 3.3, so trying to run a computer off just 12 and 5 would end poorly

**MibMib** · 01-23-2007, 09:11 AM

Hi!
About voltages now :
1. +12V - uses by HD(cd, dvd, etc ide-satadevices), intel processors psu, motherboard
2.+5v - uses by HD(and etc ide-sata devices) , amd processor psu, motherboard, some models RAM psu.
3. +3.3 V uses by sata, pci, agp devices AND IN MOST MODELS OF MOTHERBOARDS-RAM PSU!
4.-12V - uses by COM port, Infrared transmitter port, and usart

5. !!!!! -5v - DON'T used now ! typicaly in old systems was used for ISA card devices

Uh Uh Uh, You didn't say the magic word !

**novielo** · 03-23-2007, 01:18 PM

i noticed in the atx psu pinout that there's a 3.3v sense. what's that for? do i need it to make it work. and does the 5v standby needs to be standby?