Theft prevention device esp. for cycles - contains siren which sounds if securing cable is severed, and is powered by rechargeable cells

摘要

This alarm unit is designed to be permanently fixed to a bicycle or motorbike. It consists of a cylindrical housing containing rechargeable Ni-Cd batteries (10), a siren under a louvred cover and an electronic detection circuit (7). In a hinged cap on one end of the housing is a coiled flexible cable. The bicycle is immobilised by feeding the free end of the cable through the wheels and round an immovable object (e.g. a lamp-post or railings). The free end is then plugged into a socket on the side of the device and locked in place by removing a key. The cable has four cores, two carrying a positive voltage and two a negative voltage. If any of the cores are severed, the 98dB siren (11) sounds. It is almost impossible to bridge the cables before cutting, as the core insulations are all the same colour to prevent identification.