Introduction

By taking the help of modern engineering and technology, in this project we are trying to protect the school campus as well as the school bus from accidents and undesirable situations. If the bus driver tries to drive the bus after drinking alcohol, the bus engine hesitates to start. A person can’t enter into the school campus if he or she has drunken alcohol. The school main gate is locked automatically for a drunk.

Components required

1. Battery
2. Relay
3. Resistor
4. Variable resistor
5. Diode
6. Capacitor
7. Transformer
8. LED
9. 7805 voltage regulator
10. Transistor bc547
11. Switch
12. IC 555
13. Alcohol sensor

Block Diagram

Fig:- Block diagram to protect school bus.

Fig :- Block diagram to protect school campus.

Components Description

Relay

Generally relay is defined as an electromagnetic switch. The relay used here is a 12 volt ice cube type.

Resistor

A resistor restricts the flow of current. The resistors used here are carbon film and quarter watt type.

Diode 1N4007

These are general purpose diodes. These diodes have high current capability and low forward voltage drop. The average rectified output current is one ampere.

Capacitor

A capacitor stores electric charge. Capacitors used here are electrolytic and mica type.

Transformer

It consists of two coils of insulated copper wire linked by an iron core. Transformers are used to step up (increase) or step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is   no electrical connection between the coils. Here we have used a shell type step down transformer which step downs 230 volt AC to 12 volt AC. It can  supply maximum 1A current.

LED (Light Emitting Diode)

It is a transducer which converts electrical energy into light energy.

NE 555

The 8-pin NE 555 timer is the most useful ICs ever made in the world. Its popular name is timer IC. It is used in many electronics projects. Just adding a few external components, it can be used to construct so many circuits. The 555 has three operating modes: Monostable mode, Astable mode and Bistable mode. It can withstand maximum supply voltage up to 16 volt. It has a maximum power dissipation up to 600mW.

7805 voltage regulator

The 7805 voltage regulator IC gives us a constant 5 volt DC power supply from a 12 volt rectified output voltage. So , where the rest of the 7 volt goes ? Actually, the rest 7 volt goes nowhere. It is dissipated as heat in the heat sink provided to the voltage regulator IC.

Transistor bc547

A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit. BC 547 is a general purpose transistor. It is an npn epitaxial silicon transistor. Its maximum collector current (DC) is 100mA.

Alcohol Sensor

The alcohol sensor is a sensor which detects ethanol in the air. When a drunk person breathes near the alcohol sensor it detects the ethanol in his breathe and provides an output based on alcohol concentration.

Working

When the bus driver starts the school bus before that he has to breath near the alcohol sensor to confirm his consciousness test. If he has not drunken alcohol everything goes fine. If he has ethanol in his breath, the sensor detects it and interrupts the ignition current to reach into the bus engine as a result engine doesn’t start. This saves the lives of entire bus students including the driver.

While entering of a suspicious person into a school campus there will be a provision for alcohol test at the entrance of school main gate. If ethanol is present in the breath of the introducer, then the gate is locked automatically without allowing the drunk into the school campus. This avoids the undesirable situations in a school campus.

Advantages

1. This saves the lives of students in the school bus including the driver. This supports road safety.
2. This avoids the undesirable situations in a school campus.