High-speed stroboscopic tachometer unit with digital readout

The usefulness of an accurate, yet simple, tachometer with a top range of 50,000 rpm is apparent. If the operation can be based on the stroboscopic principle and thus exert no loading, the application includes even very small motors where external load would appreciably affect the reading. High accuracy is not easily attained with conventional meters as the readout mechanism. Thus, if accuracies of the order of ±1 rpm out of 50,000 are contemplated, a digital or decade readout is indicated. This paper discusses the functional operation and the unit design of a system capable of accurately measuring and reading speeds from 20 to 50,000 rpm with an accuracy of ±1 rpm without mechanically loading the motor shaft being observed.