Electronic circuit design term project security alarm circuit

1. Project title:-
Security alarm

2. Security Alarm circuit
Outline:-
 Objectives
 Circuit Diagram
 Component information
 Component data sheets
 Working of circuit
 Application
Objectives:-
To design a siren which alarmthe person when somebody tries to steal the
luggage.
Circuit Diagram:-

3. Component information:-
This circuit is based on resistors ,transistors, capacitors, and speaker.
1. Resistor-
Resistor is a two terminal passivecomponent used to control the flow of
currentinto the circuit. A current through resistor is directly proportionalto
the voltage applied across resistor terminal, it comes in two variety.
2. Transistor-
Transistor is a three terminal electronic device used to amplify weak input
signals. A transistor consistof two PN junction diode connected back to
back. Transistor areof different type such as bipolar junction transistor,
Field effect transistor and photo transistor. They are mostly used in
electrical appliances due their smaller size and light weight. In addition they
posses less power hence have greater efficiency.
3. Speaker-

4. Speaker is a transducer which producesound in responseelectrical audio
signal applied at input.
4. Capacitor-
Capacitor is a two terminal passive component which stores electric
charge. Capacitors consists of two conductors which are separated by a
dielectric medium. It works when potential difference applied across the
conductors polarizes the dipole ions to store the charge in the dielectric
medium. Capacitor comes in two variety.
 Polarised capacitor
They have polarity means + and - sign. They are basically used to store
charge. As they storechargethey should be carefully dischargebefore
troubleshooting the circuit.
 Non polarised capacitor
They does not have polarity and can be mounted any way. They are
basically used to remove the fluctuation present in conversion of AC to DC.
Component Data sheets:-
1. Transistor C945(NPN)
2. Transistor C1383(NPN)

7. Working of circuit:-
This circuit sounds when B point is connected to A through the switch .when
switch in A position the circuit is in normal condition when we move the switch to
B the transistor C945 is connected to the capacitor circuit is closed and the
voltage is supplied to the speaker to sounds.
Different alarms have different working mechanisms. For instance, thesystem
may usea beam light, which sweeps the area next the door and a photo sensor
on the other side of the room. Whenever the beam is broken, the photo sensor
notices the variation in the amount of light and rings a bell.
Applications:-
This security alarm circuit can be used to protect your valuable documents and
jewellery from theft or intruder. Just put the switch under the mat or in front of
locker so that when unauthorised person come it will walk over the switch and
this will trigger the circuit and alarm start sounding.
 The main advantage of this circuit is that it can be used as police siren or
ambulance siren.
 Home security