DC Power distribution - Nix the Transformers?

MailtoDelete asks: "I have most of my electronic gear plugged into a couple power strips hanging off a UPS. Most of these devices have big block-type transformers which, besides being bulky, are a bit of an eyesore. I have been trying to find a product out there somewhere that would allow me to have one central transformer that would distribute DC power at variable voltages, depending on what devices I wish to plug into it (think one AC input and 9 or so DC outputs individually adjustable). I found this device that resembles what I have in mind, but it does not have sufficient output for my router, switches, and various other devices. Is there a product on the market already that would do this? Can I build one with my marginally above average soldering and electrical schematic skills? Have any of you found a better way to eliminate these blocky plug-hogs?"

Re:Hardware Wars

[thegrassyknowl]

Wasn't it Thomas Edison who tried to prove that Tesla's 3 phase AC power distribution was dangerous by electrocuting frogs with it and showing how they thrash about vioilently before they died?

*tongue firmly in cheek*
Perhaps DC power distribution is the best after all.

That said, you could easily build a device to power all those said gizmos. You'd really need a quite large multi-tap transformer with appropriate ratings, and a set of voltage regulators for the various voltages... 5, 6, 9, 12, 13.8, possibly a couple of adjustable ones for those pesky items that insist on odd voltages.

I had a similar (homebuilt) device with 6 outputs, all individually regulated.

This is a good excuse for a PIC-type project to set the ouput for each port... It could adjust the regulator to get the right voltage and also toggle relays for each port to get the right transformer tap (so as to avoid dissipating too much energy in the little regulators) for any given voltage.

Re:Hardware Wars

[alienw]

He was as much an inventor as Bill Gates is a programmer. Above all, he was a businessman. Most of "his" inventions were actually created by the people working for him.

A non-home solution

[Yobgod Ababua]

It's designed for large scale server rooms, and as such won't particularly adapt to what you want, but this does show that others have had the same thoughts and are applying them to various niches. They do also explain what they see as the benefits of this arrangement.

http://www.rackable.com/products/dcpower.htm [rackable.com]

OMG...

[malejko]

I swear reading most of these ask slashdot's are slowly killing me from the inside out.

If you're pissed that a block takes up like 3 ports on a surge protector, get a short extension cord like this: http://www.radioshack.com/product.asp?catalog_name =CTLG&category_name=CTLG_009_001_003_000&product_i d=61-2755 [radioshack.com] , but if you want ONE DC converter with various voltages, you're just asking for trouble. An eyesore they may be, but they're quite safe for the most part and do their job properly.

Re:Wireless power!

[fm6]

Already been tried! [prometheus.al.ru]

Re:Liberator

[Tintivilus]

I'm actually kinda partial to Dr. Ferd's Wart Remover [samash.com]. It's only two-wire (how many grounded wall warts do you have?) and it has a nice big box on the outlet end so you can use a pad of double-sticky mounting tape to hold the mess together.

In places where I have a bunch of wall-warts hanging around, I like to use a Furman Pluglock [samash.com] power strip to keep then together and strapped down. I broke down and bought a couple of these when I got sick of having random things come unplugged in the pile of crap under/behind my desk, and they turned out to be a great buy. They're built like tanks, too.

Re:Why?

[voisine]

Good point. I've had atx power supplies fail in spectacular fasion. Scared the crap out of me. I bought a used one and the local computer junk store, plugged it in, turned around, and then *KABLAM*. It was loud enough to make my ears ring. Then thick black acrid smoke started pouring out the back. I took it apart to investigate what the hell happened. It was a fairly large blown capacitor. I had no idea those could explode like that until after this little episode.

You can't afford to do it right

[ikeleib]

DC power distribution is used in telecomm applications. They use a 48V bus and use DC/DC converters to get the required voltages. The DC/DC converters are expensive, and the AC->48V converter is also expensive.

You could just get auto-adapters for all your crap and then use an AC->12V converter. However, I imagine that this is more work than it's worth.

Why not just do what everybody else does and get more outlet strips?

Re:No.

[Hank Reardon]

Why not one voltage (the highest required by the system) with oodles of current behind it, then simply regulate it down for each voltage.

I seem to remember from my electronics courses, many years ago that the LM series of regulators work similarly to a resistor; they dissipate over-voltages as heat. Now, while you do need some overhead voltage for the regulator to function properly, too much and you'll fry the thing. The TO220 package also had a maximum current rating of somewhere in the neighborhood of 1.5 ampres with a 6-volt DC input last time I used one and the current rating went down the higher the input voltage.

Also, don't forget you just can't hook any DC power regulator right up to the transformer as a transformer is an AC device. You'll need to add a half-wave (bleah!) or full-wave rectifier and some filtering caps to feed your regulator with. Figure .7 to 1.5 volts of voltage drop across the rectifier, and I high voltage mark of 12 volts. The LM7812 will work with 13.8 volts on the input, but you'll probably want more like 15-18 volts. At this point you're talking dropping the voltage 10 to 13 volts with the LM7805. I'd be willing to bet the regulater would, at best, smell really bad while operating and, at worst, burst into flames under significant load.

I tried many times in my youth to make some regulated circuits for running various 12-volt equipment that required anywhere from 3 to 30 ampres of current. The high-current regulators were always incredibly expensive and the lower-current (read: affordable at Radio Shack) devices always ran out of smoke.

As other people have mentioned in the articles, it's just not something that anybody other than the Telecom industry uses. The equipment is expensive as all hell and, while it makes the UPS system more simple (think 48-volts right off of huge bank of lead-acid cells), effecient, high-current DC-to-DC regulators are typically out of reach of the low budget tinkerer.

Re:Hardware Wars

[Grab]

Alert - getting patents and getting a reputation for stuff your lab does do not mean you're so damn hot. In fact, it doesn't even mean you invented it - witness the *many* times Edison ripped stuff straight off other people. Nor does it mean the inventions are any damn good - Edison was quite happy to use publicity, lawsuits and outright lies to promote his stuff and crap on other people's stuff.

So a lot like Billy Gates and his organisation, in fact...

Grab.

DC power distribution

[budgenator]

In the Army we used DC power for some applications, it's an nasty problematic way of distributing power and tends to be unreliable, if at all possible avoid it. If you are wondering why, it reinforces the fact you don't know enough about real-world power distribution to do it with out it cause more problems than it creates.
DC is dangerous, if you get shocked by it it holds on to you more, there is no pauses in the current to allow you to get off the conductor. DC is dangerous, generaly it needs much more current for a give power because the voltage is lower, short curcuits tend to arc-weld together; Avoid DC power distribution when ever possible.

Point-of-load DC-DC converters do this

[Animats]

It's becoming common to use internal DC distribution within large electronic systems, then use a final DC-DC converter near the point of load. Typically, you convert the incoming AC line to 12VDC, distribute the 12VDC, then use point of load switching regulators [v-infinity.com] each place you need power.

This, in fact, is what's happening when you have devices powered off USB, FireWire, or Ethernet. Read this discussion of how USB power distribution works. [micrel.com]

So the parts exist to do what the original poster wants to do. But they're not typically packaged for the end user.