. Elementary and dental radiography / by Howard Riley Raper . Fig. 19. Diagrammatic illustration showing the action of an electric switch. The singlearrows mark the course of what we shall call (not knowing a better name) the originalcircuit. The double arrows mark an extended circuit. The drawing shows the switch—one of the double knife variety—closed. With the switch open the current couldnot pass through the extended circuit. X-RAY MACHINES 2$ When the X-rays are used for their therapeutic value, long ex-posures are made; so long that undue heating of the electrolytic inter-rupter would be
. Elementary and dental radiography / by Howard Riley Raper . Fig. 19. Diagrammatic illustration showing the action of an electric switch. The singlearrows mark the course of what we shall call (not knowing a better name) the originalcircuit. The double arrows mark an extended circuit. The drawing shows the switch—one of the double knife variety—closed. With the switch open the current couldnot pass through the extended circuit. X-RAY MACHINES 2$ When the X-rays are used for their therapeutic value, long ex-posures are made; so long that undue heating of the electrolytic inter-rupter would be sure to occur. Hence, for this work the mercury turbineinterrupter (Fig. 21) is best. In principle the mercury turbine is amechanical interrupter, depending on no chemical change for its action,being operated by means of an electric motor. We shall not consider it. Fig. 20. Non-water cooled one-point electrolytic interrupter. further, for it should not be used for picture work, except in the absenceof an electrolytic interrupter. The mechanical interrupter, or vibrator (Fig. 22), is used only onthe smallest coils. The principle on which it operates is the one involvedin the construction of electric bells; Fig. 25 illustrates the principle. A isa movable arm with fulcrum at B. When the current travels, the pathmarked with arrows, the electro-magnet, C, draws the movable arm, A,over to it, breaking the circuit at D. When the circuit is broken theelectro-magnet loses its magnetism and the spring, E, draws the movablearm back, re-establishing the circuit. The rapidity of interruptions maybe regulated by altering the strength of the spring. A popular form ofvibrator is the ribbon vibrator illustrated in Fig. 26. 24 ELEMENTARY RADIOGRAPHY In tracing the current directly from the supplyRectifier. wire into the interrupter, we have assumed, as stated, t
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