Here's the situation on a laptop computer. An adapter takes 110V 60Hz AC from the wall and provides DC. The battery takes DC, saves it, and provides it. The computer runs on DC.
Here's the current situation on a desktop computer with a UPS. An adapter takes 110V 60Hz AC from the wall and provides DC. The battery takes DC, saves it, and provides it. An adapter takes DC from the battery and produces 110V 60Hz AC. The power supply takes 110V 60Hz AC from the second adapter and produces DC. The computer runs on DC. Huh?
``Maybe I don't want to pay for a battery,'' you say. ``Sometimes I just want an AC-to-DC power supply.'' But that's not the issue. My question is about desktop computers that do have batteries. Why do they convert AC-to-DC-to-AC-to-DC instead of simply AC-to-DC?
I looked around in March 2001 and found two companies selling battery-backed ATX power supplies: American Advanced Power (which sells through Globtek) and Amsdell. Why aren't these products more widely available?
Anyway, here are some power supplies I've used:
| Computer | Date | Source | Power supply |
|---|---|---|---|
| muncher | 1998-09-30 | ASA Computers | $113.50+$35.50: 300-watt PC Power & Cooling power supply + generic mid-tower ATX case |
| twog | 2000-07-17 | Micro X-Press | $85+$7: 300-watt Antec power supply (PP303X) and mid-tower case (KS282) + extra Ultra-Cool case fan |
| stoneport | 2001-02-27 | Micro X-Press | $77+$5+$6: 300-watt Antec power supply (PP303X) and mid-tower case (KS282) + extra case fan + smart fan |
| forcewall | 2001-02-27 | Micro X-Press | $77+$5+$6: 300-watt Antec power supply (PP303X) and mid-tower case (KS282) + extra case fan + smart fan |
| thoth | 2001-02-27 | Micro X-Press | $77+$5+$6: 300-watt Antec power supply (PP303X) and mid-tower case (KS282) + extra case fan + smart fan |
| crystal | 2001-02-27 | Micro X-Press | $81+$6: 300-watt Inwin IW-S508-IW P4 power supply and mid-tower case + extra case fan |
| silverton | 2001-03-19 | Minotaur | $76+$6.40+$8.20: 300-watt Enlight EN-72370X3A power supply and mid-tower case + extra Antec case fan + extra Antec case fan |
| fireball | 2002-03-14 | UIC freebie | not sure yet |