UPS built into computers

The goal of this question is to only supply power to a computer long enough for it to stay up from a flash blackout. (no monitor) I am not
talking about even enough power to allow for shutdown. At least 90% of the time the power goes down here is just from the flash blackout. This could happen 3 times with only 2 or 3 seconds down time. So what I am talking about is 10 seconds backup for a computer with say a 400w PS.
Anyone know what something like this would add to the cost of a computer? How small do you think the battery could be? Think it could be small enough to mount in a 5.25inch bay? Could it be built to just accept the connections from the PS and then furnish the connections to the mobo?
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Op 6/29/2011 9:36 PM, Metspitzer schreef:

Just add a bunch of capacitors.
--
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tuinkabouter wrote:

Yawn. That might handle a few milliseconds. If they could handle a real outage the turnon currnt would trip the main breaker in the building, since they would charge on the first cycle. (1/60th of a second)
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On Fri, 01 Jul 2011 07:29:52 -0400, "Michael A. Terrell"

Seriously? You can't figure a way to limit the charging current?
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"dave y." wrote:

Seriously? Show me how to do that, and still be ready for the next dropout a few seconds later. It's not like you have hours or days between dropouts. Calculate how large of a capacitor you need to hold the power supply at full output for just 10 seconds. then see how long it will take to charge at near the normal supply current. Also calculate the size of all the required capacitors and consider the safety implications if some or all explode from a line surge. I've seen electrolytics go through the ceiling, and others rip the screws out of a metal case when they exploded.
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wrote:

The BEST large electrolytics are lead-acid :-)
John
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John Nice wrote:

That isn't a capacitor, and do you want a lead acid battery to vent inside a PC case? :)
There was a "UPS on a card" for the original PC/XT computers that took three slots that I saw one ad for.
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Michael A. Terrell Inscribed thus:

I've still got one of those ! Its sitting back in its box somewhere in the garage. If I recollect correctly it was only capable of sustaining the original IBM XT for about 5 minutes. Yes it gave you time to park the HDD heads and switch off. But considering that during a power failure you couldn't see anything on the screen and it didn't activate a shut down automatically, it was worthless !
Michael, mine took three slots and two of those were covered by the sealed lead acid battery. It also had a tendency to get quite hot whilst charging the battery. All in all an expensive gimmick !
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wrote:

Would you consider it worthless during the times when the power just blinked? This happens much more frequently than a power outage.
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Metspitzer wrote:

Yes. They cost more than a real UPS, and were unreliable.
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Pretty sure that display was fed internally by a mere 12 Volts.
I still have my "Hi Res" (for the day) Ball, green phosphor, monochrome 720x350 Hercules type display and I run it from a 12V dongle or even a 9V battery all the time.
The heater and the anode are the biggest loads. I'd bet that the XT integrated display does not get fed 120 VAC, so there would be no issue with parking heads, etc.. You would have time.
The place for the UPS is EXTERNAL to the PC. This thread is lame, because just like 63/37 solder, we scientists figured out the best way a long time ago.
The UPS is a separate entity from the computer. Dopes that try to build better mouse traps should be better at choosing what mouse traps need improvement first.
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Baron wrote:

That was my thought when I saw the press release. Of course, 95% of the early UPS for desktop computers were crap. Companies would spring up, then disappear a few months later.
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wrote:

The most parts efficient solution would be two 4700uf x 200v electros at the switchmode's line to DC conversion stage with diodes and resistors. The caps are about 40mm x 90mm in size, so plan on a suitable enclosure somewhere inside the computer case. It would likely run a few seconds, someone else can do the math. The Digikey prices are around 18 USD each so I would go buy the external UPS.
--
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THAT IS STUPID.

" Somewhere"? You did not think this through, did you, dumbass?

Certainly not you. You cannot even do the conceptual end.

No shit? D'oh!

You glom onto whatever you think is "cool" eh? Try to glom onto some brains first.
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George Jetson wrote:

You still aren't dealing with the turn on surge. What good would it do, if you trip a circuit breaker when you turn the computer on? You can't just stick a big pair of caps in the computer and call it a day.
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Michael A. Terrell Inscribed thus:

Its possible that the "power good" signal would be delayed enough to compensate for the capacitor charge time. Equally its also possible that the initial surge would simply shut down the PSU altogether preventing a power up at all !
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Baron wrote:

If it was a simple fix, someone would be selling power supplies touting the advantage. Gamers will buy almost anything at almost any price.
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Michael A. Terrell Inscribed thus:

Too true !
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Remember, there is often a fair bit of wire between your computer and your circuit breaker panel, it has resistance. All switch mode PSUs have a filter at there input with an inductor in line with the supply, inductance will limit current surges (If you did go down this road you might have to replace it with an inductor of higher current rating - but don't change the value).
How many other appliances or pieces of equipment do you have which also have high surge currents - motors, heaters, arc welder - do they trip your incoming breaker every time they are used? I doubt the size of capacitor mentioned here would have much effect in the grand order of things, especially as George mentioned resistors in his post - presumably current limiting.
--
Stuart Winsor

Midland RISC OS show - Sat July 9th 2011
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Michael is discussiong a power on surge. That power on surge can have other consequences. One common solution is to also install an inrush current limiter. Low voltage is desireable when first powering on electronics.
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