*Linear* regulators burn up the excess voltage as heat, switching regulators convert the excess voltage to current. Unless you are dealing with a few tens of milliamps or less, linear regulators are obsolete and much better solutions are available.
http://www.ebay.com/itm/DC-DC-Converter-Buck-Step-Down-Regulator-LM2596-Power-Supply-3-30V-To-1-21-18V-/120962074605?pt=LH_DefaultDomain_0&hash=item1c29e6c7ed
I've used the LM2596 and related parts in many applications and they work very well.
A UPS is nothing more than an inverter with a built in battery and charger, and when it comes to inverters, the ones in inexpensive consumer grade UPS's are lousy. They're intended to run for a few minutes once in a rare while when the power goes out, and usually the batteries are trashed after a few power outages. You'd be lucky to get 20 minutes of run time from a SLA battery that would fit inside a compact Mac if you want to step it up to 120V to feed the power supply.
http://www.ebay.com/itm/DC-DC-Converter-Buck-Step-Down-Regulator-LM2596-Power-Supply-3-30V-To-1-21-18V-/120962074605?pt=LH_DefaultDomain_0&hash=item1c29e6c7ed
I've used the LM2596 and related parts in many applications and they work very well.
A UPS is nothing more than an inverter with a built in battery and charger, and when it comes to inverters, the ones in inexpensive consumer grade UPS's are lousy. They're intended to run for a few minutes once in a rare while when the power goes out, and usually the batteries are trashed after a few power outages. You'd be lucky to get 20 minutes of run time from a SLA battery that would fit inside a compact Mac if you want to step it up to 120V to feed the power supply.