. The telephone system of the British post office. A practical handbook . Figure 40. Short-Civcuiting Arrangements. 5t There are some magneto-generators which are joined up so as to cut outthe magneto bell and ring direct on to line, but it is very questionablewhether this is altogether an advantage. The amount of force requiredto turn the handle when the wire is disconnected and when the circuit iscomplete is very different, so that perhaps this indication might be deemedsufficient. This plan is adopted in connection with the call wire system inoperation at Manchester. Another plan for bringi
. The telephone system of the British post office. A practical handbook . Figure 40. Short-Civcuiting Arrangements. 5t There are some magneto-generators which are joined up so as to cut outthe magneto bell and ring direct on to line, but it is very questionablewhether this is altogether an advantage. The amount of force requiredto turn the handle when the wire is disconnected and when the circuit iscomplete is very different, so that perhaps this indication might be deemedsufficient. This plan is adopted in connection with the call wire system inoperation at Manchester. Another plan for bringing about this short-circuiting of the armature isto place a disc of brass upon the spindle. Near the edge of this disc ahole about half an inch long is cut. A sleeve is placed upon the spindle,and upon this sleeve is placed a crank which carries a pin fixed at right. Figure 41. angles to it and passing through this slot. The pin is held to one end ofthe slot. The other end of the slot is insulated with ebonite. On re-volving the crank the pin moves from the metal on to the ebonite at theother end of the slot, and then begins to rotate the armature. It will beseen that the disc and pin are in contact when the generator is at rest,and are disconnected when the pin rests upon the ebonite. In the formerposition the armature is short-circuited. In yet another form of generator, a spring with a small weight or bobfixed to the end of it is screwed on to the armature. The spring restsupon a contact. When the armature is rotated the bob, owing to centri- E a 5^ Ericsson Table Sei. fugal force, flies away from the contact, thus breaking the form of instrument is very little used, and is not so reliable as thefirst-mentioned device, which is now almost universally adopted. We have now considered all the essential parts of a magneto-generat
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelepho, bookyear1901
