Richardson's handbook of projection (1927)

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576 HANDBOOK OF PROJECTION FOR (see D, Fig. 187), whereupon the shaking magnet pulls the tube over to one side, or, in other words,#"rocks" it, thus allowing the mercury in cathode B, Fig. 183, to bridge over and form a connection with the mercury in starting anode C which shunts the current from the starting anode relay D, Fig. 187, circuit, and operates to demagnetize its coil, thus allowing its plunger to fall and open the shaking magnet circuit, whereupon the tube, by its own weight, rocks back into vertical position, thus breaking the mercury bridge between anode C and cathode B. After the tube has started operating, and the arc has been struck, the series underload relay which is connected in the D. C. circuit picks up, thus cutting the starting anode relay and shaking magnet entirely out of circuit. If the tube does not start at once the shaking magnet will continue to rock the tube until it does. INSTALLATION.— After the rectifier set has been uncrated and placed in its operating location (see "Installation," page 569), the tube should be placed in the holders E, F, as per Fig. 185. This is accomplished by pressing the narrow part of the tube, just above anode arms A, Al, Fig. 183, into upper clip E, Fig. 185, carefully lowering the tube until anodes A, Al, Fig. 183, rest on the lower clips, F, Fig. 185. Having the tube in place, you will find four wires covered with a sort of glass bead insulation, these wires terminating in brass spring clips, Fig. 188. Connect the two upper ones (either one to either anode) to anodes A, Al, the small lower one to starting anode C, Fig. 183, and the large lower one to cathode B, Fig. 183, as shown in Fig. 185. Next connect the A. C. supply lines to the two terminals, marked A-C, at the upper left-hand corner of the panel — that is to say, the left-hand corner as you stand facing the tube on the back side of the machine. Next connect the positive D. C. terminal, Fig. 185, marked + to one side of the projector table switch, and through the projector table switch to the upper carbon arm of the lamp, and connect the negative (marked) D. C. terminal to the other side of the projector table switch, and through it to the lower carbon arm of the lamp. Connect the adapting links in the front of the panel according to the voltage of your alternating current supply, as already directed. Having accomplished all this, with the triple-pole switch closed in the upper position, as per Fig. 184, and with the A. C. supply and D. C. projector table switch closed, the rectifier is ready to start.