I've blogged several times before about my desire for universal DC power -- ideally with smart power, but even standardized power supplies would be a start.

However, here's a way to get partyway, cheap. PC power supplies are really cheap, fairly good, and very, very powerful. They put out lots of voltages. Most of the power is at +5v, +12v and now +3.3v. Some of the power is also available at -5v and -12v in many of them. The positive voltages above can be available as much as 30 to 40 amps! The -5 and -12 are typically lower power, 300 to 500ma, but sometimes more.

So what I want somebody to build is a cheap adapter kit (or a series of them) that plug into the standard molex of PC power supplies, and then split out into banks at various voltages, using the simple dual-pin found in Radio Shack's universal power supplies with changeable tips. USB jacks at +5 volts, with power but no data, would also be available because that's becoming the closest thing we have to a universal power plug.

There would be two forms of this kit. One form would be meant to be plugged into a running PC, and have a thick wire running out a hole or slot to a power console. This would allow powering devices that you don't mind (or even desire) turning off when the PC is off. Network hubs, USB hubs, perhaps even phones and battery chargers etc. It would not have access to the +3.3v directly, as the hard drive molex connector normally just gives the +5 and 12 with plenty of power.

A second form of the kit would be intended to get its own power supply. It might have a box. These supplies are cheap, and anybody with an old PC has one lying around free, too. Ideally one with a variable speed fan since you're not going to use even a fraction of the capacity of this supply and so won't get it that hot. You might even be able to kill the fan to keep it quiet with low use. This kit would have a switch to turn the PS on, of course, as modern ones only go on under simple motherboard control.

Now with the full set of voltages, it should be noted you can also get +7v (from 5 to 12), 8.7v (call it 9) from 3.3 to 12, 1.7v (probably not that useful), and at lower currents, 10v (-5 to +5), 17v (too bad that's low current as a lot of laptops like this), 24v, 8.3v, and 15.3v.

On top of that, you can use voltage regulators to produce the other popular voltages, in particular 6v from 7, and 9v from 12 and so on. Special tips would be sold to do this. This is a little bit wasteful but super-cheap and quite common.

Anyway, point is, you would get a single box and you could plug almost all your DC devices into it, and it would be cheap-cheap-cheap, because of the low price of PC supplies. About the only popular thing you can't plug in are the 16v and 22v laptops which require 4 amps or so. 12v laptops of course would do fine. At the main popular voltages you would have more current than you could ever use, in fact fuses might be in order. Ideally you could have splitters, so if you have a small array of boxes close together you can get simple wiring.

Finally, somebody should just sell nice boxes with all this together, since the parts for PC power supplies are dirt cheap, the boxes would be easy to make, and replace almost all your power supplies. Get tips for common cell phone chargers (voltage regulators can do the job here as currents are so small) as well as battery chargers available with the kit. (These are already commonly available, in many cases from the USB jack which should be provided.) And throw in special plugs for external USB hard drives (which want 12v and 5v just like the internal drives.)

There is a downside. If the power supply fails, everything is off. You may want to keep the old supplies in storage. Some day I envision that devices just don't come with power supplies, you are expected to have a box like this unless the power need is very odd. If you start drawing serious amperage the fan will need to go on and you might hear it, but it should be pretty quiet in the better power supplies.