D.S.S hand made on GPB (General Purpose Board)

Introduction

• You can use this simple and reliable security system as a watch-dog by installing the sensing loops around your building. You have to stretch the loop wires two feet above the ground to sense the mises. Wire loops a, 2 and 4 are connected to the A, B and G inputs of 7-segmentsdecoders 4511(IC1) respectively, while the D input of IC1 is grounded permanently. The loops are not also connected to a dual 3- input NOR gate and inverter CD4000 (IC2) to activate the alarm.

  Fig. 1 shows the circuit of the digital security system, while Fig.2 shows the proposed wiring diagram for the loops around the Premises. Before using this security system, make sure that loops shown in Fig 2 are connected as Shown in Fig 2 are connected as shown in Fig .1. If you don't want to use a buzzer, switch it off by opening switch S2.

  The circuit works of 9V regulated power supply. However, battery back-up is recommended. A common- cathode, 7-segment display (LTS340) is used for displaying whether the Loops are intact or not.

   

  If Loop 1 is broken, the display will Show 1 .If two or all the three loops are broken, the display will show the sum of the respective broken loop numbers.For example, if loops 1 and 4 are broken, the display will show 5(1+4). When all the three loops are intact, the display will show 0. All the three inputs of gate Nl remain low to give a high output.This high output is further given to gate N2 and, as a result, Its output remains low. This keeps transistor Tl in cut-off position and the buzzer does not sound. When any loop is not broken, the output of NOR gate Nl goes low, while the output of gate N2 goes high. Transistor Tl conducts and the buzzer sound to alert you.You can mute the buzzer by switching off power to circuit through switch S1.

What is Included?

• Project Definition ( by Email )

  Project Circuit Diagram ( by Email )

  Project Report ( by Email )

  Project ( by Courier)