DC-AC Inverter for light loads

[CWatters]

I have an alarm system that I would like to put on a UPS. Problem is the UPS that I've tried aren't very happy on the light load presented by the alarm. The power consumption is virtually zero unless the alarm is sounding. I think this is causing the UPS I have to generate a lot of noise that's messing with the alarm panel.

The panel operates from a 220VAC to 9VAC mains adaptor. I've looked at a few options such as increasing the battery capacity in the alarm panel itself and feeding the panel something like 12-13V DC (which should go through it's bridge rectifier) but these introduce other problems.

So what I'm looking for ideally is a 12V DC to 220V AC pure sine wave inverter that is stable on loads from 0 to say 50W. Do such things exist as I can't find one that specifically refers to light load operation.

An alternative would be a 12V DC to 9VAC pure sine wave inverter.

 

[Rive]

The class of UPS you need is called 'home network battery backup', like the BGE50/70/90 series.
I'm sure it exists for 220V too.

 

[jim hardy]

Pure sine is going to be expensive.

This el-cheapo inverter will be happy at light load. Here in US it's under twenty bucks at Walmart, surely there's a 220 volt version in your country.
https://smedia3.webcollage.net/0144...WSLYKQ&Signature=DBWkz5FQCSQVUd3V1+LODFnYkvo=

If the problem is in your alarm panel, ie it's intolerant of a harmonic-rich power source, this inverter won't do your job. A snip from the manual: