EARTHING DEATILS

1. EARTHING BASED SECURITY
INTRODUCTION
 Thwart the attempt of burglary by detecting
intrusion with this alarm circuit.
Each door is protected by separate circuit built
around an independent 555 timer IC in conjunction
with reed switch magnet.

2. All the three units are powered from a single
power source.
The buzzer can be plugged into the earth line of a
socked in any room of the same building having proper
earth line connection.
There is no need of laying external wire up to the buzzer
unit from different rooms.

3.  For door –1 alarm unit, connect reed switch S1 near the
magnet of gate 1.Wire IC1 as a frequency oscillator and set
door-1 alarm unit to the desired frequency, say, between 1
Hz and 3 Hz, using VRI.
For door - 2 alarm unit, connect reed switch S2 near
the magnet of gate 2.
Wire IC2 also as a frequency oscillator and set door –2
alarm frequency between 5 and 7Hz using VR2.

4. For door –3 alarm unit, connect reed switch S3 near.
The magnet of gate 3.
Wire IC 3 also as a frequency oscillator and set door - 3 alarm
frequency between 10 and 12 Hz using VR3.
 The power supply required to operate the alarm circuit
consists of a bridge rectifier and filter capacitor C10.
In normal condition, i.e., when all the doors are
closed reset pin 4 of IC1 through IC3 remains low.

5. As a result, these do not oscillate and piezobuzzer PZ1
remains silent.
When door 1 in opened the magnet moves away from the
reed switch S1.
IC1 generates 1-3 Hz signals and the piezobuzzer beeps to
indicate the door-1 has been opened.
When door 2 is opened, IC2 generates 5-7 Hz signals and
piezobuzzer beeps to indicate that door 2 has been opened.

6. Similarly, when door 3 in opened the piezobuzzer
beeps at the rate of 10 to 12Hz,
this indication that door 3 has been opened.
Thus sitting in a room where the buzzer unit in fitted,
we can easily know which room has someone gained
entry into.
 Mains line wire is not connected to SOC1.

7. Live and neutral wires are connected to the primary of
the step-down transformer, which is a part of the power
supply.
All the three unites connected are powered from a
single rectified power supply.
Connect the reed switch near the particular gate magnet
through an external wire.

8. Plug-in the piezobuzzer into the earth and neutral
lines of socked (SOC2) fitted in the desired room of
the same building.
There is no need of laying external wires up to the
buzzer unit.
This project will work off the power line within the building.