(57) Device for monitoring that a complete locking operation is carried out for a combination
lock, including means (A) arranged adjacent to the dial (1) whereby the combination
lock is manually manipulated, arranged to sense the rotary direction of the dial (1),
and in association with a related electronical circuit to initiate counting of the
number of revolutions for the dial (1) when same is rotated in a direction resulting
in the release of the combination wheels within the lock, and to perform counting
until a predetermined number of revolutions while the rotary direction is maintained
unchanged. The means arranged adjacent to the dial (1) may include magnetical, conductive,
optical or mechanical sensors for monitoring the rotary direction of the dial (1).
An electric switching means is arranged to be operated when the door is closed, which
is lockable by means of the combination lock, or to be influenced when the lock bolts
are moved to a locked position, and to initiate the circuit for sensing rotary movement
of the dial (1). A timer circuit is preferably connected at the same time, arranged
to cause transmission of alarm, preferably of audio type, should the dial (1) not
be rotated predetermined number of revolutions in a predetermined rotary direction
within a time period monitored by the timer circuit. The entire device is preferably
arranged to receive a voltage supply from a battery voltage source, preferably with
a battery voltage monitoring circuit, arranged to indicate when the battery voltage
drops below a predetermined lower limit.
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