Stroboscopic Method of Speed Measurement

Stroboscopic Method of Speed Measurement Points : Stroboscopic Method of Speed Measurement The stroboscope is a simple, portable manually operated device which may be used for measurement of periodic or rotary motions. Basically, the instrument is a source of variable frequency flashing brilliant light, the flashing frequency being set by the operator. The circuit used is based upon variable frequency oscillator which controls the flashing frequency. The speed is measured by adjusting the frequency so that the moving objects are visible only at specific intervals of time. The method of use of the stroboscope depends upon imperfect dynamic response of the human eye. If a strong light is caused to flash on a moving object which, at the time of each flash occurs, occupies a given position, the object will appear to be stationary. The stroboscope consists of a source of flashing light whose frequency can be varied and controlled. This source is called “strobotron”. Shaft Speed Measurement A distinctive mark is made on the shaft or on a disc attached to the shaft as shown. A stroboscope is made to flash light directly on the mark. The flashing frequency is adjusted until the mark appears stationary. Under these conditions, the speed is equal to the flashing frequency provided that the approximate speed of the shaft is known in advance and the flashing frequency is not allowed to depart too much away from this value. The scale of the stroboscope is calibrated in terms of speed which can be directly read off.