The Stroboscope is a portable strobe lamp equipped with a handle for easy carrying. It is powered through a flexible power cable fitted with a grounded ac plug.

The stroboscope has two modes of operation that are switch-selectable. In the internal mode of operation, the strobe lamp is triggered from the ac line frequency. In the external mode of operation, the strobe lamp is triggered by a separate signal source, from 1 Hz to 120 Hz, applied to the external input terminals. In this mode, the stroboscope can be used as a "strobe tachometer" to measure slip speed. Any function or audio frequency (AF) generator module can be used as the external signal source. The strobe fires at the precise instant the triggering signal rises and passes through zero.

The Stroboscope, when used with phase shift indicators (Model 8906 or 8909), can accurately measure the rotor pole shift of a synchronous motor/generator, as well as the slip speed of non-synchronous machines.