RAJLAXMI SAHA(4th YEAR EE) ORISSA ENGINEERING COLLEGE

INTRODUCTION COMPONENTS USED CIRCUIT EXPLANATION ADVANTAGES PRECAUTIONS CONCLUSION

NOW-A-DAYS DESKTOP HAS BEEN REPLACED BY LAPTOP WHICH IS A DEFORMED FORM. SO IT HAS BECOME EASIER FOR THEFT TO STEEL OUR VALUABLE LAPTOP. TO OVERCOME THIS KIND OF STEELING A LAPTOP PROTECTOR IS REALISED,WHICH WILL PROTECT BY ITS MINIATURE ALARM.

i) REGISTERS: RESISTORS ARE THE ELECTRONIC COMPONENTS WHICH OPPOSES CURRENT. RESISTORS OBEY OHM’S LAW. DIFFERENT KIND OF RESULT COMES WITH RESPECT TO APPLICATION OF VARIOUS VOLTAGES.

ii) CAPACITORS: A CAPACITOR IS AN ELECTRICAL OR ELECTRONICS DEVICE THAT CAN STORE ENERGY THE ELECTRIC FIELD BETWEEN A PAIR OF CONDUCTORS. THE PROCESS OF STORING ENERGY IS CALLED ‘CHARGING’. A 47microF 25V CAPACITOR IS USED.

iii) INTEGRATED CIRCUITS: IT CONSISTS OF MINIATURIZED ELECTRONIC COMPONENTS BUILT INTO AN ELECTRICAL NETWORK. HERE TWO ANALOG DESIGNED IC ARE USED. -IC TLO71(IC1):IC1 IS USED AS VOLTAGE COMAPARATOR. -IC CD4538(IC2):IC2 IS USED AS A MONOSTABLE WITH TIMING ELEMENTS R5 AND C1.

iv) DIODE: IN DIODES CURRENT IS DIRECTLY RELATED TO VOLTAGE. DIODES ARE NON-LINEAR,TWO TERMINAL, PASSIVE ELECTRICAL DEVICES. A 1 JUNCTION DIODE (1N4148) IS USED IN THIS CIRCUIT. v) BATTERY: A 9V BATTERY IS USED

vi) TRANSISTOR: TRANSISTOR AMPLIFY CURRENT AND VOLTAGE. IT MAY BE USED AS SWITCH. A pnp TRANSISTOR BC558(T1) IS USED IN THIS CIRCUIT.

vii) SWITCHES: a) TILT SWITCH: A TILT SWITCH IS MADE UP OF PLASTIC BOTTLE WITH TWO STAINLESS PINS AS CONTACT OR PROBES. IN TILT SWITCH 2/3 RD OF THE BOTTLE IS FILLED WITH WATER SUCH THAT THE WATER CANNOT MAKE CONTACT WITH THE PINS. b) ON/OFF SWITCH: A ON/OFF SWITCH OF 3A IS USED. THE USER CAN USE THE SWITCH AS PER HIS REQUIREMENTS.

viii) PIEZO BUZZER: A PIEZO-BUZZER IS USED AS AN ALARM. USERS CAN USE ANY BUZZER AS PER THEIR CONVINIENCE. ix) PRINTED CIRCUIT BOARD: ALL THE ABOVE EQUIPMENTS ARE MOUNTED ON THE GENERAL PURPOSE PCB.

THE UNIT IS INSIDE THE LAPTOP CASE IN HORIZONTAL POSITION. IN THIS POSITION, WATER INSIDE THE TILT SWITCH EFFECTIVELY SHORTS THE CONTACTS, SO THE OUTPUT OF IC1 REMAINS LOW. THE ALARM GENERATOR REMAINS SILENT IN THE STAND BY MODE AS TIGGER PIN 5 OF IC2 IS LOW. WHEN SOMEONE TRIES TO TAKE THE LAPTOP CASE, THE UNIT TAKES THE VERTICAL POSITION & THE TILT SWITCH BREAKS THE ELECTRICAL CONTACT BETWEEN THE PROBES. IMMEDIATELY THE OUTPUT OF IC1 BECOMES HIGH & MONOSTABLE IC2 IS TRIGGERED. THE LOW OUTPUT OF IC2 TRIGGERS THE pnp TRANSISTOR(T1) & THE BUZZER STARTS BEEPING.

1.CHEAPNESS: It is affordable for general use. 2.CLEANLINESS: It is clean as it doesn’t produce fume or poisonous gas. 3.AVAILABILITY: All equipments used in this circuit are easily available in the market. 4.EASY CONSTRUCTION: It is easy to construct for a person who has general idea about circuitry elements.

1.THERE SHOULD BE NO LEAKAGE IN TILT SWITCH. 2.BEFORE LEAVING THE LAPTOP THE USER SHOULD CONSIOUSLY ON THE SWITCH.

THE LAPTOP PERFORMS DIFFERENT TASK IN DAY-TO-DAY LIFE. SO,IT SHOULD BE PROTECTED. KEEP THE LAPTOP CASE IN HORIZONTAL POSITION & SWITCH ON THE UNIT.LAPTOP IS NOW PROTECTED.