Burglar security alarmPresented by group members1-junaid arshad2-pc badar mehmood3-imran younas4-gc irshan hussain5-gc hanzala liaqat

Applicationes of security alarm

• Burglar security alarms are used for the security purposes in homes and offices.

Circuit elements

• Elements which are required to make a simple security alarm are as follow

• 1-transistors(pnp@npn)type

• 2-capacitors

• 3-resistors

• 4-buzzer

Circuit elements

• capcitors

• transistors

elements

• resistors

• buzzer

Circuit diagram

Functioning of the circuit

Phase 1:we have applied a 3 volts of dc source to the whole circuit. In phase no 1 a capacitor is attached In parallel with voltage source . Capacitor has the same voltage as does battery.

Capacitor is just acting as dc purifier it will just let pass ac through it and will resist dc through it due to which all the dc will flow ahead the circuit and no ac will flow

Phase no 2

Phase 2 comprises of pnp transistor in which collector is connected with the upper node .base is connected with the collector of npn transistor.

When circuit is open all the current will flow through the npn transistor which will act as a an amplifier and will convert high voltage into low voltage which will flow from collector to the base of npn transistor now as the pnp transistors collector is forward biased with the base it will allow the current to pass through the emitter and the buzzer will buzz of

Phase no 3

• Now when circuit is closed all the circuit will be shorted and current will flow through the outer path . Now as npn transistor receieves low voltage it will amplifie it to high voltage now the collector of pnp transistor is reverse biased with its base and no current will flow through it due to which buzzer will not buzz