On 09/11/2016 00:52, Dave Plowman (News) wrote:

snip

Assuming the 18v supply can provide enough current - which is likely since
an electronic device is replacing a mechanical one (I guess) a simple
voltage regulator should do the job.

Friedland make some doorbells which will *only* work on AC. They also
make doorbells which work on 8V AC or 6V DC. The implication there is
that the bisexual ones are solenoid operated and the higher AC is needed
to overcome the coil impedance at 50Hz.

Page 62 of this...

https://www.friedland.co.uk/Document...gue%202008.pdf

Why guess? I'm sure you've come across these on old houses - the
illuminated push button with a dim under-run (for longevity) lamp which
goes out when you press the bell.

Cheers
--
Syd