i need to know this because my science project is due tomorro and i choose a alarm system as my project....i had a way to do it but i left the book with the instuctions in school! plz i need help its due tomorro!!!!!
2007-11-25 10:01:35 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
You can make a really simple-minded one with batteries, a horn, wires, and one or more normally closed momentary- contact switches.
You wire them all in series and mount the switch so that a closed door or a closed window holds it down (so it is out of its normal position and breaks the circuit open ). When the window or door is opened the switch is released and returns to its normal closed position. That lets the circuit be completed and the bell can ring.
Professional alarms usually have a small resistor across each switch so that a little current always flows and is enough to monitor that the wires are not broken (by keeping a little lamp on).
2007-11-25 10:15:17 · answer #1 · answered by Rich Z 7 · 0⤊ 0⤋
no
...but i'll go get macgyver's number for you
2007-11-25 18:05:36 · answer #2 · answered by man on the mountain 3 · 0⤊ 0⤋