Mike wrote:

"Ian Stirling" wrote in message
...
Sounds like you recommend a brew-it-yourself solution then ? :-)

In some ways yes.
However.

Many UPSs are designed for short term use.
For example, some have heatsinks that are only designed to put up with
a few minutes use at nominal load, as the tiny batteries put in it will
have discharged by then.
snip
Will do.


(If you manage to kill yourself or burn down your house as a consequence
of this posting, I reserve the right to point and laugh).

Well I've designed a kW audio amp before and that could fry you without
thinking about it.

So what's the problem?
All you need is a 50Hz sine-wave oscillator, some lead-acid batteries, and
a charger

Actually inverters are nasty to design, because you never know what
somebodies going to plug in.
For example, a large series universal motor being repeatedly switched
from backwards to forwards, ...


If you've got the skills, then you can take a good quality inverter, and a
largish 3-stage charger, and connect it to a bunch of batteries.
3 stage battery charger circuit