Need a 13.8 VDC power supply? Got any old computers laying around?

I read a few "how-to's" and watched some worthless youtube videos, but this guy has got the answer!

http://boginjr.com/electronics/lv/atx-mod/

My interest in amateur radio got me looking for a cheapo 13.8 VDC power supply. Having more than a handful of old computers laying around, my mind naturally considered the PSU out of a desktop computer. There are plenty of write-ups which suggest that a load on the 5-volt output and an adjustment of a potentiometer will give you a useful supply. However, none of the supplies I looked at had any such potentiometer.

The author of the article in the above link however, documents a procedure by which a potentiometer may be added to the regulator IC in the PSU and allow full adjustment of the output voltage from 5 to 15 VDC or so. Parts are readily available from Radio Shack or an online business such as Parts Express.

After making a nifty paperweight out of my first attempt (make sure you've got all the wires properly insulated and secured before you power up your project!) I got my next effort to perform flawlessly!

Modifying and repurposing an old computer power supply for use with a 2-meter mobile radio--what could be more grassroots than that?

Hope someone finds this useful, or at least interesting!

Neat. Do you need a precisely controlled voltage independent of current draw for amateur radio?

RossD wrote: Neat. Do you need a precisely controlled voltage independent of current draw for amateur radio?

Kenwood recommends 13.8 VDC at a minimum of 14 Amps for my radio. That, or wire it into a car's electrical system.

1988RedT2 wrote:

RossD wrote: Neat. Do you need a precisely controlled voltage independent of current draw for amateur radio?

Kenwood recommends 13.8 VDC at a minimum of 14 Amps for my radio. That, or wire it into a car's electrical system.

14 amps? You putting out 200w?

Strizzo wrote:

1988RedT2 wrote:

RossD wrote: Neat. Do you need a precisely controlled voltage independent of current draw for amateur radio?

Kenwood recommends 13.8 VDC at a minimum of 14 Amps for my radio. That, or wire it into a car's electrical system.

14 amps? You putting out 200w?

Naw. High power setting is like 55 watts. I work the repeater with the low power setting which is like 20 watts. I've got a panel meter between the PSU and the radio for Volts and Amps so I can make sure the supply is doing okay. Voltage does not drop noticeably on transmit and it pulls 6 Amps on low power setting. Haven't tried it on high power yet...

Awesome! Computer power supplies are also great to use for bench work, 5v and 12v are very usable when testing / working on things. Most car stuff (radios, etc) runs fine on 11 - 14v so 12v is right there. I love the DIY adjustable regulator.

I have a "real" bench-top adjustable power supply from back in my tech days but this is a cheaper way to get it. And everyone that works on electronics and car things should have an adjustable power supply.

I use an old AT computer power supply for charging phones and stuff. The 12v is wired to o couple of lighter plugs in the housing and the 5v is wired to a USB hub sitting on top.

I'm looking for a 12V power supply, 5 amps is more is great. If you have one, lemme know.