From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The principles of stroboscopic illumination and synchronisation using the 'STROBORAMA' instrument.
| Identifier | ExFiles\Box 155\3\ scan0135 | |
| Date | 1st March 1937 guessed | |
| interference of daylight or artificial light and observations may be easily conducted without darkening the room. The image of the mechanism appears so clear, and so sharp, that it is strongly impressed upon the eye, sending a strong, quick and lasting message to the brain. Written or spoken words fail to convey the value or effect of this strong illumination. Vision is a physical reaction on the optic nerve: the stronger the reaction the better is the vision. Perhaps the following illustration will bring out the point. If someone strokes your hand with a feather you feel it very slightly, and the impression disappears quickly. But if someone strikes your hand with a club you feel it intensely and the impression is lasting. In other words, powerful physical reactions send quicker and more lasting messages to the brain, and this is especially true of vision. CURRENT CONTROL AND SYNCHRONISATION: The production of intense illumination demands a high-tension current. Obviously, such a current cannot be passed through a mechanical contact-breaker, as backflash would inevitably ensue, destroying the instantaneous nature of the flash and giving a blurred image as a result. The means adopted to surmount this fundamental difficulty constitute the predominating feature of the "STROBORAMA", which thus represents revolutionary progress in the development of stroboscopic instruments. In the STROBORAMA for the operation of which 1-1/2 KW of alternating current of either 110 or 220 volts, 50 to 60 cycles, single phase, is required, a rotary contact breaker (Fig.l),Sy, constituting the synchroniser, produces intermittent discharges of a low-capacity condenser, charged to a few hundred volts by a continuous current generator M2G, in the primary winding of a high frequency transformer, which raises the tension to produce a discharge of the current through the Neon Tube,N. This discharge is the"priming current", which controls the passage of the illuminating current. ---------- The illuminating current is prepared in the high tension transformer T. Alternating current is raised to a high voltage(15,000 volts) required for illuminating the Neon tube; a rectifying valve changes the Alternating current to direct in order to maintain constantly charged a powerful battery of condensers, C. To discharge through the Neon tube, N, the current must pass across a spark gap, E, adjustable so that the resistance of the gap, added to the resistance of the Neon Tube, does not permit the condenser to discharge. When the priming current passes through the Neon Tube, it reduces the resistance of the system, and the condenser discharges through the gap and through the tube. It will be appreciated that only the priming current passes through the contact breaker, and, as the separate illuminating circuit has practically no self induction, an intense light flash of such extremely short duration is produced that parts of mechanisms moving at a linear or peripheral speed of 350 feet per second, appear with sharp and distinct contours, and without any distortion of form or size. By this simple arrangement, the "STROBORAMA" can control fast interruptions of an illuminating current of extremely high power. INDEPENDENT SYNCHRONISER. An invaluable feature of the Stroborama is its independent synchroniser. This not only saves the lengthy and tedious labour of effecting connection with the mechanisms to be observed, but it makes it possible to show the mechanism, not merely standing still, but also with a continuous forward or backward movement at any desired speed. This often uncovers parasitic effects otherwise impossible to detect. When an interesting portion of the motion is particularly desirable to study, it can be rocked to and fro: the experimenter may concentrate his observation on a specific amplitude of the motion, leaving his mind undisturbed by what may be taking place in other portions of the cycle. Another value to this feature is, that when different parts of a mechanism are moving at different speeds, they may be brought to rest successively, at a moments notice. Page 2. | ||