Mailbox for detecting package contents and letter bombs

摘要

An accumulator or a spur from the mains supply (1) supplies current to a light-reflecting case (4) in a mailbox, and to a pulse generator (14) outside a mailbox and an acoustic signal generator. The case has a triple reflector beneath the mailbox emptying flap. It emits a pulsing focussed ray from a transmitting diode through a polarizing filter onto the triple reflector. Breaking this ray triggers the detection process and warning messages are sent to an approaching person.