How can I get -30v and +22v from computer PSU?

Thread Starter


Joined Mar 22, 2009
Hi, everyone.

I'm a hobbiest and I have an older satellite reciver that needs a new PSU.

Since the manufacturer has long since disappeared, I can't order a replacement.

Fortunately, a spare computer psu has all the voltage outputs I need, except for the following three rails (which are regulated, so voltage should not vary too much):

-30vdc @ 900mA
+22vdc @ 900mA
+22vdc @ 900mA

So, is there a simple-to-build (at least not too complex) circuit available that I can take the 12vdc @ 25A rail from the computer PSU and boost it to what I need? :confused:

I've search using Google and on this site, but I can't find what I need (at least something that doesn't assume I have an advanced degree in electronics engineering!). :(

Thanks in advance to all who reply. :D


Joined Jul 17, 2007
Unfortunately, trying to "roll your own" DC-DC boost converter isn't all that simple or inexpensive. You COULD go to National Semiconductor's website and have their Webench tool design the supplies for you, but by the time you got done, you'd be spending around $40 for each boost converter.

Instead, you might consider picking up a few supplies that are already assembled. Marlin P. Jones usually has some pretty good deals.
Here's a couple of supplies you might consider:
Both have adjustments for the output voltage; you could probably "tweak" them to within a volt or so of what you need.

No chance of fixing the old supply, eh?