A trigger activated switch for a firearm is disclosed. The switch
comprises a Hall-effect sensor configured to be mounted in the housing or
frame of the firearm, and a magnet disposed on a retractable member
coupled to the trigger of the gun. The trigger comprises a firing module
rotatably coupled to the housing to have a range of motion with respect
to the housing from a non-firing position to a firing position. The
retractable member is moveably coupled to the firing module and
articulates between a non-engaged position and engaged position with
respect to the firing module. The Hall-effect sensor is attached to the
firearm housing in proximity to the magnet when the retractable member is
in the non-engaged position. Motion of the retractable member from the
non-engaged position to the engaged position causes the magnet to
articulate away from the sensor, which then activates an auxiliary device
upon sensing motion of the retractable member.