PSU no 3v line

[TheDogFather]

I dont know much about power supplies, but if I had one with only 5 and 12 volt lines could I mod the 5 down to 3.3 and how would I do it ?

[TheDogFather]

Just to clarify things a little, I stumbled on a power supply on ebay, there wasnt lomg left and it was cheap so I bought it.

It was used for powering 20 hard drives in a server.

Allthough it has no 3.3v line it seems to have plenty of power, so was wondering if I could use/modify it to run my system.

The info on it :

WAKE UP!! You are bidding on a very high quality WEIR heavy duty power supply unit. Part number : WP605 11 00 03 Manufactured by Weir part of LAMBDA GROUP of Unitech PLC. The item is not new but has been removed from upgraded equipment. The input voltage can be from 115 volts 8amp 50/60hz to 230volt 4amp 50/60hz. The unit has a rating of 550watts. Outputs 1) 5.00 volts at 65amps 2) 12.00 volts at 15amps 3) 12.00 volts at 10amps 4) 5.20 volts at 15amps 5) 12.00 volts at 15amps The voltages of all 5 outputs are adjustable plus or minus 10% Combined output not to exceed 550 watts This power supply unit was used to provide supply to a 20 hard drive server installation. Unit cost new, was in the region of £500 . Take a look at the Farnell or RS catalogues! Were talking QUALITY /RELIABILITY here! Was designed to meet worldwide safety and RFI approvals. Shipping weight is 4kgs Unit dimensions are Length:300mm, Width:190mm, Height:50mm. UK shipping by City Link is £7.50 (Do not ask me to POST this item in UK!) Surface mail USA/Canada is £36.40 ($55) e-mail me for other destinations Can also despatch by UPS or Fed-Ex on YOUR account worldwide. Please view my other auction items on e-bay

Thanks in advance.

[felix88]

power supplies also have -5v and -12v rails.

[TheDogFather]

What is that -5 and -12. I dont understand the differance between +and- when it comes to electricity.

Any ideas what runs of what ?

Anyway this supply also has -5 and -12 but as I said no 3volt at all, how can I get around this ?

[felix88]

-5v and -12v are basically the same as 5v and 12v, except the electricty is flowing in the opposite direction. i could go into more detail, but i usually don't make much sense when i do.

from what you have listed in your 2nd post, it doesn't have any negative rails.

as for getting 3v out of the 5v rail, it shouldn't be too hard. you'll just have to build a voltage regulator.

[TheDogFather]

It came this morning, the terminals marked on it are:
0v +12v -5v 0v -12v 0v 0v +12v PF +se +so -se -so the +se/+so have 5v marked above them, the -se/-so have 0v theres also some other unmarked connectors.

Ive been trying to find some specs for it but no luck yet.