"Emil Tiades" wrote in message
news
On Sat, 16 Feb 2008 23:34:24 GMT, geoff wrote:



All you need is a tweeter and a 20KHz oscillator!

From the "this is what you old farts would hear" articles, it's more
like beats - so you would need two oscillators, somewhat higher than 20k
of course

You would also need a teenager in a cage for tests

Why a cage?
Why not just a random passer by?


Anyway these things don't work against the trouble makers just the ones that
hang around the shops.
The trouble makers will just destroy the device and probably torch the shop.
It isn't an offence to hang about, if you think it is just remember that the
next time you stop in the street to talk to someone you know.