Do I need -5V for an AT

**mp3commander** · 02-23-2002, 01:36 AM

I have a DC-DC power supply model: MDP-8051S , it doesn't have -5V.

do I really need it?
if I need it, how can I get that voltage?
Im using Irman, and serial character LCD from Crystafontz.

anybody using this PS?

**Rob Withey** · 02-23-2002, 04:12 AM

That really depends a lot on the motherboard you are using. I'm running an embedded mobo which only requires +5v and +12v for example.

Rob

**magnetik** · 02-24-2002, 06:25 PM

not essential, BUT serial ports and some onboard sound cards need -5V to function..... since you have an Irman, your gonna need it!....

unless you can use a USB ---> serial converter.... since the USB port only has 5V+ in its plug......

**mp3commander** · 02-25-2002, 12:07 AM

Can I do this?

**THEMP3KID** · 02-25-2002, 01:07 AM

No, you can't do that, the input to the -5volt regulator should go to the -12volt rail..

**mp3commander** · 02-25-2002, 02:02 AM

Sorry that was a mistake. now should be ok.

**Aaron Cake** · 02-25-2002, 09:14 AM

Yes, that will be fine. Though I would also put a 10uF capacitor at the input of the regultor, and add a 0.1uF unit at the output. The result will be a much more stable -5V.

**mp3commander** · 02-25-2002, 12:35 PM

Originally posted by Aaron Cake
Yes, that will be fine. Though I would also put a 10uF capacitor at the input of the regultor, and add a 0.1uF unit at the output. The result will be a much more stable -5V.

do you mean like this?

sorry for my ignorance, I don't know much about electronics.