1.) a ups with a built in voltage regulator with constant output,
     not a relay or sensor activated designed to switch between
     battery, charger, or source AC.


This is important- not all UPS's actually regulate voltage. My current UPS
only clicks over when the voltage drops significantly. As a result, a lot of
noise and brownouts get through - I believe the baseline APC models are like
this as well; you need the "Smart UPS Pro" before you actually get voltage
regulation. In any event, make sure you're aware of what you're buying. :)

Philo

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