Stroboscopic timing system por record player turntable - uses compound array of markings to provide synchronisation at either 50 Hz on 60 Hz AC supply

摘要

The stroboscopic system uses an array of markings, alternatively light and dark to indicate by the stroboscopic effect the speed of rotation of a record player turntable. The markings comprise short radial lines near the edge of the upper surface of the rotating platform. In order that the platform speed may be checked using either 50Hz or 60Hz supply, two interdigitated marking patterns are provided. Over a 20 degrees range identical markings are provided to give both 5 and 6 equal spaces. This permits stroboscopic timing using 50 or 60 Hz supply.