Popular science monthly . DOORCLOSED CIRCUIT B4TTERV B/^TTERY Spring contact in a door-lock for soundinga burglar alarm when the door is opened disengaged from the spring the circuit isbroken, allowing the armature of thebell magnets to spring back, closing thecircuit.—Charles W. Christman. 947 !)4S Popular Science Montlib/ A Dead End Switch of the Multiple-Point Type DIAD end switches usually bring tomind the picture of a rotary diskwith some sort of puzzling springs andcontacts mounted around its edge. The KNOB CONTACT^ SirrrcH uver. One of the contacts shown in detailand the wiring diagram
Popular science monthly . DOORCLOSED CIRCUIT B4TTERV B/^TTERY Spring contact in a door-lock for soundinga burglar alarm when the door is opened disengaged from the spring the circuit isbroken, allowing the armature of thebell magnets to spring back, closing thecircuit.—Charles W. Christman. 947 !)4S Popular Science Montlib/ A Dead End Switch of the Multiple-Point Type DIAD end switches usually bring tomind the picture of a rotary diskwith some sort of puzzling springs andcontacts mounted around its edge. The KNOB CONTACT^ SirrrcH uver. One of the contacts shown in detailand the wiring diagram for the switch switch illustrated here is, to all appearances,a regular multiple-point type, yet it isdoing all that any dead end switch canpossibly do. As will be seen the contacts fit into ahole cut through the front of the case andextend about 14 ? to the rear. The rearend is soldered to a short spring-brass stripthat normally keeps it pushed outward,the end of the strip making contact with asmall screw. The switch-lever should bestiff and its edges curved to glide over thepoints, moving them inward about s in- The parts arc attached to a board of in-sulation, either wood, vulcanite, slate orhard rubber; the wood, however, is easiestcovered. The operation will be apparent if youkeep in mind that the switch-Icvcr breaksthe circuit beyond each point on which itrests. Thus, considering the hook-up, shouldllu lever be placcfl on point I, itwill push the spring out of contact withtlic small screw, leaving coil A in thecircuit,
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
