This paper deals with the filtering of images of objects in a CAD system, that simultaneously move in very fast and slow motion, so that their dynamics can be observed in truthfully time scaled VR. Micro-Electro-Mechanical systems (MEMS) are miniaturized mechanical or optical equipment less than a millimetre in size. While some have movable parts, such as membranes, valves, cantilevers, others may have only fixed parts. Those with movable parts, can flick, pump or pulsate at rates of up to 500 Hz, while other components in the same MEMS move at slower speeds. This poses a series of problems for truthfully time scaled visualizations. Due to the human being’s vision limitation, and the computer’s frame rate (which is normally 30 times per second), very fast movements can not be observed clearly, e.g. when a gear rotating in clockwise direction is in high frequency, it appears rotating counter-clockwise. In MEMS a simple truthful time scaling may result in one of the objects still at non-observable fast motion, while another practically reaches a standstill. To solve the dilemma we simulate to illuminate the moving objects with a simulated stroboscopic light. The stroboscopic simulation is demonstrated with an example of rotating gears created in a virtual interactive VRML environment. In this paper we present the results of a systematic combinatorial analysis for finding the stroboscopic illumination intervals and stroboscopic flash duration that produce useful dynamic images.