I admit it: I'm a total geek. I love electronics, programming, 3D art, vintage Apple hardware, and whisky. I'm always juggling half a dozen projects. I also enjoy documenting it all: my successes, my failures, my experiences... and everything geeky along the way.

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Bench-Top Power Supply, Part 1 | Kevin Rye.net - Main

Kevin Rye

Geek Extraordinaire. Yeh, I said it.

Bench-Top Power Supply, Part 1

I haven’t been into PCs for years. I switched to the Mac in 2006. As the years go by, I find myself tinkering with PCs less and less. I used to have a good 10 PCs or so all set up all over the house as file servers, print servers, FTP servers, gateways, etc. I even had a PC or two just sitting around running SETI@Home. If someone gave me an old PC, I’d fix it up, fill it with hard drives and expansion cards and find a use for it. They’ve all slowly been replaced over the years with other hardware. Everything’s Mac, Tivo, iPad, and Apple TV now. I just don’t have the need for a huge PC-based infrastructure at home anymore. For me, it’s pretty much all Mac, all the time.

The kids have a junky eMachines just for casual web browsing. If it broke, I’d probably just toss it and buy them a new one. It offers pretty much zero expansion and upgradeability. It really is a disposable computer.

As a matter of fact, if someone were to give me a Windows-based PC, I’d have no idea what to do with it. I just really have no need for a Windows-based computer anymore. If it were a brand-spanking new machine, I’d probably give it to the kids as gaming machine, but the likes of P2s and P3s are pretty much useless to me nowadays.

So last year when it came time to clean out the closet for a little Spring cleaning (not to mention coming up with some extra cash for my new Mac Pro), I came across a few totes of old NICs, video cards, modems, case fans, heatsinks, PCI slot covers, ISA cards, old mother boards, and 2 or 3 power supplies. Basically just a ton of obsolete PC hardware. I tossed what was total garbage and tried to sell the rest on eBay. It sat there for weeks and no one bit. I guess you just can’t get $5 bucks for an old power supply anymore. Needless to say, after I’d spent more on eBay insertion fees that I’d ever hope to recover, that stuff got tossed.

My wife came home today with her friend’s 12 year old junker of a Dell. This machine is toast. The motherboard is shot.


What am I supposed to do with a useless, old, broken Dell? All that’s left to do it tear it apart. It uses that short-lived RDRAM which is pretty much useless for anything. It has a CD-burner. Probably a 4x and useless. Video card? It’s a GeForce 2. Useless. Hard Drive? 40GB. Might come in handy in an old iMac one day. Hard drives always get kept.

I also kept some of the cables in case they come in handy for some electronics projects, as well as the fan. You never know when you’ll need a fan.

And then there’s the power supply.


I connected a dummy load to it and watched it power right up. It’s good.


So what am I supposed to do with a 250 watt ATX power supply?

I’ve always wanted to build myself a bench-top power supply that I can connect to my breadboard for prototyping. I always seem to be rummaging for power cords, USB cables, and adapters that are either 5 or 12 volts. Then there’s the need for 5V regulation using a 7805 in the case of 9V and 12V supplies. It’s always a pain. I’m also not a big fan of, although I do it all the time out of a sheer lack of alternatives, connecting my breadboard to the USB hub connected to my Mac.

Many a time have I gotten that “you just shorted out your Mac” message when I miswired something or a stray lead touched something it wasn’t supposed to.

I’d love to make use of Dangerous Prototypes’ ATX Breakout Board. It connects to a standard computer ATX power supply and allows you to break out the 3.3, 5, and 12 volt rails. It’s perfect. It’s cheap too; only $13.80. The Acrylic Case is an extra $4.00. Still, an awesome piece of kit for less than $20 bucks.
DP_ATXBreakout Board
You just need an ATX power supply. Finally, I have a power supply! I’ve been wanting to build one of these for almost a year but just couldn’t bring myself to buy an ATX power supply after throwing away a few of them last year.

Now it’s just a matter of waiting for the kit to arrive.

See this project from start to finish:
Bench-Top Power Supply, Part 1
Bench-Top Power Supply, Part 2