On Fri, 05 Jun 2009 11:26:12 +0100 someone who may be "Dave Plowman
(News)" wrote this:-

It must be quite a capacitor if it powers the sounder for an hour.

You can get such things - but all the bell boxes I've seen use an ordinary
re-chargeable battery.

That was certainly the case when I was involved with such things
too.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54