On Sat, 02 Jun 2012 12:18:01 +0200, Martin wrote:

My neighbour has a large garden and a lot of it is down to
vegetables
and fruit. He has an electric fence, so simple, a wire running
around
the perimeter and attached to a battery.

Isn't there something attached to battery that generates high voltage
pulses or charges up a capacitor that discharges when the wire is
touched by something?

There ought to be, known as an "energiser", as you say they generate
a pulse of electricty every second or so. I've not seen them in
ordnianry garden centres or sheds in the UK but easy to get from an
agricultral supplies place.
--
Cheers
Dave.