Protection device for external alarm signal source e.g. for burglar alarm system

摘要

The protection device is provided as a metal cage (1) which fits over the external alarm signal source (7), formed from a number of metal hoops (5) which are sufficiently spaced to prevent a key for hardened plastics foam. At least one of the metal hoops is coupled to an electric monitoring circuit for detecting attempted sabotage of the external alarm source. The protection device may be fitted to a plastics external alarm source as an optional extra.