International Library of Technology · Scranton, International Textbook Co. · leaf 709
with a small button over each drop,which when pushed will complete the circuitand cause the drop to fall if there happens tobe any door or window open. These are veryuseful for testing out to see if everything isclosed. All these appliances belong to the an-nunciator itself and do not affect the… … Fig. 28. when the alarm is set, and a movement of the window ordoor breaks this contact. Two batteries are required for 42 INTERIOR WIRING. 28 this system, one being a closed-circuit gravity battery indi-cated at b in Fig. 28, connected in series with a resistance rof about 200 ohms, the magnet…
Electrical engineering
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