Stroboscopes, like automotive timing lights, use a bright flashing light to make rapid movement appear to stand still. However, the stroboscope uses a shutter type aperture to make rapid movement appear to stop or move slowly in either direction. A spinning plate with a slot in it is driven by a small electric motor. By looking through a slot in the backing plate and adjusting the speed of the motor, an observer can essentially slow down rapid movement so that its action or position can be viewed. Detailed plans for this stroboscope can be found in volume three of The Shop Wisdom of Rudy Kouhoupt.
