Project title:-

Security alarm

Security Alarm circuit

Outline:-

Objectives

Circuit Diagram

Component information

Component data sheets

Working of circuit

Application

Objectives:-

To design a siren which alarm the person when somebody tries to steal the

luggage.

Circuit Diagram:-

Component information:-

This circuit is based on resistors ,transistors, capacitors, and speaker.

1. Resistor-

Resistor is a two terminal passive component used to control the flow of

current into the circuit. A current through resistor is directly proportional to

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 consist of two PN junction diode connected back to

back. Transistor are of 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-

Speaker is a transducer which produce sound in response electrical 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 store charge they should be carefully discharge before

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)

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, the system

may use a 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