Paul wrote: > I knew about not plugging in laser printers. I just wanted to make > sure that this older model (Back-UPS Pro 280) was good enough > quality.I had been reading about how UPS's in general don't provide > very good quality power in a blackout, so I wanted to make sure I > didn't need an upgrade that way. I have two computers upstairs, each > on a Back-UPS Pro 280, and then in my basement lab (fiendish > experiment division), I have a Back-UPS Pro 420. > > I don't think American Power Conversion makes either of these models > any more. They say they've moved to more energy efficient designs. > > Does anyone know if the Tripp Lite BC PRO450 is any good? Someone > gave me one with a dead battery, and I don't want to buy a new battery > if it's not worth using. The Back-UPS's I have all use the same > battery, but the Tripp Lite uses a smaller one. > > I've also heard that these computer UPS's aren't meant for non- > computer equipment, such as stereos or aquarium pumps.
Most UPSes output what the manufacturers call a modified sine wave. This is advertising speak for a modified square wave. Line power (what comes out of the wall) is a sine wave, very curvy. The modified sine wave is in no way curvy. A computer power supply, or any switching power supply, doesn't care. In fact the switching power supply itself produces a square wave. Ordinary transformers don't work well with a square wave. But small ones will typically tolerate it, especially for short durations. Note that many wall warts these days are switching power supplies not linear supplies (with transformers). You can buy UPSes (as well as AC Inverters) that produce a true sine wave output but they cost about 2-4 times as much as square wave units. The modified square (sine) wave UPSes produce both peak and RMS voltages that (roughly) match the line voltage. Switching power supplies are affected by the peak voltage. Lamps are affected by the RMS voltage. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
