Do-it-yourself UPS

Giampiero writes "Over at dansdata.com some guy named Dan creates a UPS out of some spare parts. To sum it up, "if you're looking for an industrial-capacity UPS solution, and don't like the prices of the off-the-peg options, it might be easier than you think to roll your own."" Of course you can mentally substitute U.S. 110 volts for Australian 220 volts wherever necessary...

Comments

Be Careful

[TibbonZero]

Please, everyone take caution when working with high voltage and moreso, high ampre compenents. We don't want any fried ./ers

Re:Be Careful

[stienman]

This indicates that something is seriously wrong with your UPS. If it did drive a current or voltage across the input power plugs it'd be powering the building grid which is not only illegal, but those doing so are liable for any damage to the power grid and associated line workers. They take just as much protection for a downed grid as a live one for stupid users who try to power a downed grid, but several die each year because someone's power went out and their generator/UPS/alternative power system was back feeding the utility company when the grid was down. Connecting two mismatched live grids together is fun for the whole family.

If your UPS is UL listed then there are several regulations which govern just this sort of action. Report the problem to APC, if they don't do anything about it (!!!) then report it to the UL and/or BBB.

I'm being completely serious. For it to go this bad there is certian to be more wrong with it. I wouldn't trust it to power anything worth more than $10.

-Adam

Re:Be Careful

[paxil]

I could hold a 1 volt 300000 amp power supply's leads all day and not be hurt. The reason is Ohms law.

Although what you say is mostly correct from a practical point of view, try not to forget that "ohms law" is an idealization and only applies to a small class of conductors. What G. S. Ohm noticed more than a hundred years ago what the in metalic conductors at a constant temperature the ratio of electric field to current density was approximately a constant, known as the resistivity. (note that this is a microscopic statement.) Working from this assumtion that rho=E/J, and assuming an isotropic, ohmic conductor, one easily arrives at the more familliar version of ohms law: R=V/I. Now this is a very usefull result, but please remember that it was drived only after making multiple assumptions regarding the nature of the conducting material and has noting to say with regard to what is going on at a smaller scale.

Anyways, just be carefull you don't read too much into "ohms law".

A tunnel diode is not a bad example of something you can hold in your hand which is most deffinately not ohmic and exhibits some interesting behavior because of this.

Electrochemical systems (such as collections of cells in a human body) are another good example of decidedly non-ohmic systems. Pick up a physical chemistry book if you want to learn more.

The take home point is: Yes, you could probably hold on to a 1v supply with no problem, but the effects of electricity on the body are not as simple as you make them seem.

And, No, I am not one of those people who think cell phones or power lines are harmfull :)

Australia runs 240 V, not 220

[Anonymous Coward]

did you even read the article?

Re:Why convert DC to AC to DC?

[seanadams.com]

So why not save some money and bypass this, by running the PC straight off the battery (like a laptop)?

A latop doesn't run "straight off the battery". It has a switching power supply circuit which is not entirely unlike your desktop's AC->DC supply. Most of the stuff in there runs at 3.3V, whereas the battery is 18V or more. So you still need a power supply.

For desktop PCs, a 110V->5V supply is cheaper than a DC-DC supply.

Re:why australia?

[Zeddicus_Z]

The Dans Data article was originally written by Dan for our magazine, Atomic Maximum Power Computing.

As we're an Australian mag with a (mostly - we sell in New Zealand, Singapore and a few other places) Australian audience, its setup for 240V.

The UPS D-I-Y article appeared in AtomicMPC Issue 13 (latest issue is 18)

Standard Internet Horror Story

[_bobs.pizza_]

• some guy creates cool thing
• said guy puts directions on his homepage
• some bored /.er finds it, submits it to /.
• editor likes it, it gets posted
• INSTANT DEATH to the guy's homepage
• inventor guy looks at how many hits he's gotten, realizes why server is dead
• guy learns not to share innovations online

This is how we thank people that invent cool things in this day and age.

12v DC input ATX power supplies...

[Radi-0-head]

I think these are what you're looking for:

http://www.keypower.com/DC_power/DX-250H.htm