Fredxxx wrote in :

On 24/02/2014 21:14, Bill Wright wrote:
harryagain wrote:


The other good news is that they use electricity all the time.
Whereas a battery operated doorbell only uses power when a finger is
on the button.

So how much does 1kWh cost if you get it from AA cells?

Most small transformers consume a few watts, say 5? 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.

When we bought the house we wanted a Buzzer (AC) and an illuminated
button. The house already had a transformer.

It is the replacement DIN rail that is the problem. I guess that a
wireless one would be my choice now.

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DerbyBorn