In message , Andy Champ
writes
Mogga wrote:
On Sat, 16 Feb 2008 15:12:56 +0000, Emil Tiades
wrote:

On Sat, 16 Feb 2008 10:50:35 +0000, Mr Flibble
wrote:

Bit of bother with some of the local teenage hoods, and considering
installing one of these outside the house. Has anyone tried them, or
had any success with them ? What sort of range do they have ?
Bloody expensive to purchase outright though
http://www.personalalarms.com/store/erol.html#1X0
That page doesn't load for me. Either that or I'm too impatient
http://themidgeatershop.shopkit.net/
£499.00 (Inc. Vat)

:O

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



--
geoff