larkim was thinking very hard :
I know there are some battery only devices, but they are all horrible and
don't meet SWMBO's audio requirements nor visual aesthetic requirements. And
wiring something up doesn't meet my requirements. (And wireless ones are
either crap, don't work in my house, look ugly or don't make the right sort
of ring for SWMBO!).

All maybe true in the distant past, but pay a bit extra for a good
quality modern one and none of that is true. If range is an issue, then
get one of the longer range versions.

The only good reason to have a wired system with a transformer, is if
you must have a light on the push. Run on battery they do not last
long. A wired battery one without a light is otherwise fine, but most
installing one these days choose a wireless option.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk