In message , "Dave Plowman (News)"
writes
In article ,
Fredxxx wrote:
Most small transformers consume a few watts, say 5?

Where did that figure come from?

Given there are
8,700 hours a year that equates to 43.5kWHrs, which at 10p per unit
would be roughly £4.35

That pays for quite a few alkaline batteries at Poundland. Plus
batteries don't "buzz" in the bedroom above.

Batteries go flat. Usually at the most inconvenient time.

As this is a DiY group, how about having 2 batteries, main and standby,
with an auto change over circuit that gives an indication when it has
operated so that you have a couple of years warning that you need to
change the flat battery?


--
Bill