For timing motion in one dimension on a piece of paper in the form ofdots spaced at equal interval of time. An electromagnet enclosed in abox operates on 12V AC through a pair of 4mm sockets. The screw shapedhammer on the armature mounted at the top of enclosure moves up/downwith the changing polarity of electromagnet and leaves well defined doton paper strip moving beneath carbon paper disc. Guides on top ofenclosure assure smooth and straight movement of paper strip. Amplitudeof vibration of hammer can be varied to get sharp dot and relativeposition of carbon discs with respect to paper tape adjustable fortheir optimum use. Includes a stand for mounting paper tape roll.Complete assembly mounted on a stable, non-skid base. Supplied completewith paper tape and carbon paper discs.