This is something I've always thought about. Essentially what the PC requires are +/-12Volts, and +/- 5V. Why dont they come out with a standard for a 'power supply port'? Since the current requirement for the -ve voltages is minimal, wouldnt it make a lot of sense to just connect the motherboard to a battery thru proper rectifiers to block current when the power is present? The most expensive electronic stage in a conventional UPS, the inverter, could be completely eliminated. The battery could have an external charger, or the 'port' could have a source trickling back from the SMPS to charge it. The negative voltages could be derived from the battery as well. I do have a feeling i am missing something here, but what is it? Anand ----- Original Message ----- From: "Peter Mcalpine" To: Sent: Wednesday, January 02, 2002 5:55 AM Subject: [EE]: Small UPS > Hi All and happy new year :) > > I want to make a small UPS, one that would be able to run my > PC for a little while if the power failed (enough so it can > shutdown it self down properly). > > 2 ways I have thought of doing it. > 1st would be a 240V to 12Vbattery back to 240V that can be run > in series with the incoming supply. > 2nd would be to modify the existing switch mode computer power > supply to include the battery. > > I would like to do the second method as that sounds easier :) > > Any suggestions or pointers to websites that may help me out? > > Thanks! > Peter Mcalpine > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads