Manual

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T
his burglar alarm makes a buzzing sound when
anyone sneaking into your house trips over a wire
a
nd breaks it off or disconnects it from a terminal.
Try to figure out how to connect a switch to the door
of your house, so that the alarm sounds when a
burglar opens the door, instead of stretching out the
wire.
Start by sliding the switch to position B and
assembling the circuit. When you complete the
wiring, connect the terminals 13 and 14 to the long
wire, and slide the switch to position A to turn on the
power. No sound comes from the speaker, at this
time.
Detach the wire from terminal 13,to test the alarm.
The speaker gives out a beep. This beep is the
alarm that tells you a burglar is about the break into
your house.
As you can observe in the schematic, this burglar
alarm uses the operational amplifier as an astable
multivibrator, as the electronic buzzer in the last
experiment did. You can change its frequency by
using different values for the 10kW resistor and the
0.1mF capacitor. Note how the tone of the buzzer
alters when you set the 10kW resistor to 47kW or
switch the 100kW and 220kW resistors with each
other.
N
otes:
EXPERIMENT #92: BURGLAR BUZZER
Schematic
Wiring Sequence:
o 1-29
o 2-30
o 3-114
o 5-14-83-70-110-121
o 13-89-68109
o 81-63-132
o 67-90-92-113
o 69-82-84-91
o 119-124
o 122-131
o 13-14 (LONG WIRE)
EP-130_62315RevC.qxp_EP-130_062812 6/23/15 11:17 AM Page 111