Junkbox parts: PC power supply

[KJ4IVD]

Here at work, we are recycling a quantity of old computer power supplies. Most failed because of that bad batch of Asian capacitors that made tech news a few years ago.

The pieces that didn't fail look pretty robust and can live again as something new. There are several good-sized power supply caps (not the hi-freq ones that leaked), stout power transformers, some speedy switching transistors and as many as 4 or five toroids on each board.

I've seen the "Das Derelicht" webpage that showed how a dead CFL bulb lived again as a QRP transmitter. Has anyone done anything interesting with parts from a dead computer power supply?

[KD0HFZ]

cant say that i have...although before those PS's get out of reach, HARVEST!

[WB2WIK]

Here at work, we are recycling a quantity of old computer power supplies. Most failed because of that bad batch of Asian capacitors that made tech news a few years ago.

The pieces that didn't fail look pretty robust and can live again as something new. There are several good-sized power supply caps (not the hi-freq ones that leaked), stout power transformers, some speedy switching transistors and as many as 4 or five toroids on each board.

I've seen the "Das Derelicht" webpage that showed how a dead CFL bulb lived again as a QRP transmitter. Has anyone done anything interesting with parts from a dead computer power supply?

Hard to justify, since other than the magnetics, there's nothing in a PC power supply that costs more than ten cents. Seriously. That's why a 450W power supply can sell for $30 and it has hundreds of parts.

I do use an old PC power supply every single day, though, seriously: It is installed midway between the garage and the laundry room. It's on the floor, blocking the laundry room door so when the wind comes along, the door doesn't slam shut.

[KJ4IVD]

I do use an old PC power supply every single day, though, seriously: It is installed midway between the garage and the laundry room. It's on the floor, blocking the laundry room door so when the wind comes along, the door doesn't slam shut.

HAHA! Just the right size and cheaper than a brick!

...other than the magnetics, there's nothing in a PC power supply that costs more than ten cents.

You won't get any lip from me on that point. But those 10-cent parts don't come with a $7 shipping fee, like one or two of my usual fave supply houses charge.
For me, its like the guy with the CFL bulb: I've got this thing with some parts that look like they'll still work, now what the hell can I do with them?
FWIW, I have an iso transformer and a relay from a 1994 modem, a couple of opto-isolators and some transistors from two PS's --- enough crap-tastic parts to make a rig/PC interface (with PTT logic, PSK31 to mic input, radio output to soundcard in, and CW keying). Now that's the kinda jazz I'm talking about.

[N0YAX]

Not that long ago, I used an old AT-style power supply as a 12V supply for my old IC-2AT brick HT that monitored APRS. Took an old dead battery pack, pulled the cells, and wired yellow and black wires from the supply to the positive and negative terminals of the pack. Worked pretty well!

[W9GB]

Might provide parts for a large amperage (40 amps) switch mode power supply.

13.8V 40 AMP SWITCHING POWER SUPPLY
Manfred Nornhinweg, XQ2FOD
QST December 1998 / January 1999 issues.
Link below to his web page
http://ludens.cl/Electron/PS40/PS40.html

This is a true switching power supply that rectifies the input line AC voltage and switches the DC into a transformer at 25KHz.
BUH1215 transistors and a LM3524 switching power supply controller IC are used.
The three (3) transformers and chokes are wound on cores available from Amidon, Thompson, Phillips, or TDK.
A complete description on how to wind the transformers and chokes is described in the article.

FAR Circuits has the PC boards.
http://www.farcircuits.net/power2.htm
ARRL members can download articles to build or you can read about in later ARRL Handbooks.
http://ludens.cl/Electron/PS40/PS40.html

[KI6ZIF]

I agree with the couple of others. Get to harvesting.

At the very least you can repair one, and have at the least a 12v 5-10a power suply (depending on the 12v rails capability), AND a 5v supply..

Plenty of reasons to have 4 or 5 of those puppies around for parts.

And I completely agree with the supply of $.10 parts, without the $7 shipping fee. Bastards.....

[AE1PT]

Google "St. Louis Switcher power supply" and your questions will be answered. In reality, all that is required to convert a computer PS is a ballast resistor on the 5 volt rail. I used a 10 ohm 20 watt wirewound potted block for mine. Here is a fairly decent link:

http://www.angelfire.com/planet/als_...e_switcher.pdf

For mine, I chose a 700w supply that had 30A capability on the 12 volt rail. As you can see, there is a switch on the front to a shunt that doubles the ammeter capacity to 30A. Everything except the PS (from NewEgg) came out of the junk box, including the meter. Total cost--$35. You can likely pick up the caps you need to repair one of the defective ones for just a couple bucks--especially if you include them with a larger order of "got to have its" from Mouser... Here is the one I built, heavy duty connectors on the back running to a PowerPole pigtail:

[KJ4IVD]

I like what everyone is saying here; repurposing a PC power supply for use in Amateur Radio. Good moneysaver and great examples of how to "make-do" with what you have on hand.

I'm really interested however in knowing if anyone has actually gutted a blown PS and made something else useful for ham radio. Has anyone salvaged the magnetics to use in a tuner, filter or balun; or can a couple of those high-speed transistors go into a QRP transmitter? Right away I can see an empty chassis is an ideal enclosure for a forced air-cooled dummy load.

There's got to be more ideas out there.

[AD2U]

The magnetics in a typcial computer PS are of the low frequecy types, which will be very lossy even for HF usage, except for the 160M band.

The power transistors have similar problem. Certain computer PS use Power MOSFET for the high voltage switcher, which might be good for HF linear amplifer for the 160/80/75M bands.

Personally, I used magnetic wires from the 3.3V/5V choke for my QRP antenna tuner - the big yellow ones on the lower part of the following image.

I like what everyone is saying here; repurposing a PC power supply for use in Amateur Radio. Good moneysaver and great examples of how to "make-do" with what you have on hand.

I'm really interested however in knowing if anyone has actually gutted a blown PS and made something else useful for ham radio. Has anyone salvaged the magnetics to use in a tuner, filter or balun; or can a couple of those high-speed transistors go into a QRP transmitter? Right away I can see an empty chassis is an ideal enclosure for a forced air-cooled dummy load.

There's got to be more ideas out there.