Magnetic compass bearing attachment devices for use as a separate entity and either with or without binoculars or the like for selectively and temporarily holding the bearing of the compass rose or card, after an object or target sighting has been made therewith. The devices are purely mechanical and include a weight-activated, pivotally mounted bell-crank lever system of which the weight, responsive to respective front and back tilting of the device during use, moves the card clamping end of the bell-crank lever between card-release and peripheral card-clamping positions. The weight in one form is connected at one side of the lever and is a float member immersed within damping fluid, as is the clamping lever, whereby a center of lift of the float shifts from one side to the other of a clamping axis to help effect said respective clamping lever positions with the clamping being in a direction from beneath a damping-fluid-immersed compass card. In another form the weight and clamping lever are disposed above a freely rotatable compass card, and an arm of the lever applies clamping pressure under the same basic principle of operation, but from above the compass card of a compass assembly which need not be of the damping fluid immersed type. A further refinement includes the provision of a tubular peep sight affixed preferably diametrically beneath the compass casing and transversely to the aforementioned pivotal clamping axis, to facilitate use of the devices independently of binoculars.
A portable hand held battery operated flashlight having mounted thereon, a magnetic compass which receives illumination from the flashlight or which may have its own illuminating means. The compass is mounted such that compass readings may be taken by the holder of the flashlight whenever the flashlight is illuminated.
A low cost head tracker for a virtual reality head set for determining the orientation of the head set relative to the earth's magnetic field includes a magnetic sensor responsive to the earth's magnetic field, and disposed on the head set and arranged with respect to a vertical axis of rotation of the head set to produce a displacement signal relative to the angular displacement of the head set with respect to a calibration orientation relative to the earth's magnetic field, and a signal processor connected to the magnetic sensor, and responsive to the electrical displacement signal for producing an output signal proportional to the orientation of the head set relative to the calibration orientation.
