Xref: utzoo comp.periphs:1343 sci.electronics:4472 Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!rutgers!mcnc!ecsvax!cjl From: cjl@ecsvax.uncecs.edu (Charles Lord) Newsgroups: comp.periphs,sci.electronics Subject: Re: Computer uninterruptable power supply Message-ID: <6078@ecsvax.uncecs.edu> Date: 11 Dec 88 05:33:21 GMT References: <1167@viscous> Distribution: na Organization: Triangle R&D Corp,RTP,NC Lines: 24 As for computers that do what you suggest off-the-shelf, most laptops work just that way. I used to use an old Datavue 25, non-backlit LCD and all, just because with AC and batt was a "built-in" UPS. Those usually have a 12V to 5V DC/DC conv with a wall xfmr. There is at least one batt based PS for the XT/AT/386 boxes that has an intermediate battery stage. The problem with this type of system is that the computer needs relatively accurate and highly stable supply voltages, and would require regulating pre-battery and post-battery. The typical micro's PS is a switcher that rectifies 120VAC to 120VDC (nominal), then switches at a few kilohertz through xfmrs to the regulated voltages. There is never a 12v +/-3v intermediate stage. What you CAN do is what a friend did years ago with his Apple ][: He wired a bank of 10 each 12V gel-cells (a 120v battery) at that 120VDC stage in the Aztec power supply. Worked like a charm back in the days when UPS meant megabucks. -- * Charles Lord ..!decvax!mcnc!ecsvax!cjl Usenet (old) * * Cary, NC cjl@ecsvax.UUCP Usenet (new) * * #include cjl@ecsvax.BITNET Bitnet * * #include cjl@ecsvax.uncecs.edu Internet *