thssdwv@iitmax.IIT.EDU (David William Vrona) (11/05/90)
I heard recently that it is not a good idea to plug a transformer, like those used on modems, calculators, and the like, into a UPS. Something about the UPS not having a true sine wave ??? Is this true? What's the scoop?
jgd@rsiatl.UUCP (John G. DeArmond) (11/06/90)
thssdwv@iitmax.IIT.EDU (David William Vrona) writes: >I heard recently that it is not a good idea to plug a transformer, like those >used on modems, calculators, and the like, into a UPS. Something about the >UPS not having a true sine wave ??? Is this true? What's the scoop? Gee, I guess my system is in a lot of trouble, 'cause I got a whole rack of modems and stuff plugged into our square wave UPS. Actually, it works just fine. An Anchor modem (VERY cheap) that has a marginal wall tumor gets a bit warm but everything else works just fine. The only problem I've had was with this same Anchor modem and its under-rated wall tumor. Since the peak value of the square wave AC is lower than line current, marginal linear power supplies may have undervoltage problems. My solution with the Anchor was to simply replace the wall tumor with a larger one. PCs and other devices with switchmode power supplies work just fine with no additional heating. You generally hear death and destruction tales about square wave inverters from those UPS vendors that sell sine wave units. I'd never suggest that marketing could affect engineering :-) John -- John De Armond, WD4OQC | "The truly ignorant in our society are those people Radiation Systems, Inc. | who would throw away the parts of the Constitution Atlanta, Ga | they find inconvenient." -me Defend the 2nd {emory,uunet}!rsiatl!jgd| with the same fervor as you do the 1st.