Letterbox Indicator

{Intelligent letterbox}

INTEGRATED PROJECT ON

B120020007 Abhi Markandey B120020023 Akanksha Sharma B120020024 Akashdeep Singh

GROUP MEMBERS

PROJECT GUIDE→ Mr. Jagmohan Rana

CONTENTSIntroduction

Necessity of Electronic letterbox

Components Used

Theory

Working

Pictorial Representation

Another Innovative Idea

Circuit Diagram{General}

Advantages

References

INTRODUCTION

• A device in which a LED glows if a letter is kept inside it, indicating the presence of a letter.

• To detect the presence of a letter we have used a LDR and a source of light.

• The circuit gives you a visual alarm when somebody drops a letter in your drop box.

NECESSITY OF ELECTRONIC LETTER BOXModern world is very busy-• People like to do activities easily & save time.• They don't waste time for small things.A Digital & electronic letter box is required to

detect the presence of a letter-• Many posts remain unattended since post

boxes are not checked regularly.• Use the technology if available.

COMPONENTS USED• LED LEDs form an inevitable part in the modern

electronics. Specially made diodes to emit light when a potential is applied to its anode and cathode.

• LDR To detect the presence of a letter. LDR is a

special type of resistance whose value depends upon brightness of light which is falling on it.

• IC 555  It is an integrated circuit used in a variety

of timer, pulse generation, oscillator applications. It can be used to provide time delays.

THEORY• When somebody drops letter in your letter box then

LED connected to output stops glowing indicating you that you have letter.

• To detect the presence of a letter we have used a LDR and a source of light.

• In this the source of light and LDR is so adjusted that light will fall directly fall on LDR so that when letter is dropped inside the box it will block the beam of light and LDR will be under darkness.

• The circuit gives you a visual alarm when somebody drops a letter in your drop box.

WORKING• Install LDR and LED on opposite side of the box so light from

LED constantly falls on LDR so device remain off.• Consequently output pin 6 of IC1 remains high then this high

is supplied to pin 1 which is a NOR gate and it only gives output as 1 when both the inputs are low so LED will continue to glow indicating no letter.

• As letter is dropped light falling on the LDR is obstructed and its resistance goes high.

• As a result, pin 2 of IC1 goes low which also make pin 6 low and this low is supplied to pin1 of NI1 as a result we will receive logic 0 in output pin 3.

• Therefore we will  receive logic 1 at output of pin 4 because 0 is passed to NI2 gate input from pin 3 so whatever may be the input from pin 2 we will receive high at pin 4. This we will receive high on pin and LED connected will not glow indicating no letter.

PICTORIAL REPRESENTATION

ANOTHER INNOVATIVE IDEA

• There are post boxes with audio which are triggered by letter being dropped.

• In some cases, alarm continues till the letter is removed. So, that has to be switched off.

• In letter boxes with light indicators no such problem arises.

CIRCUIT DIAGRAM{GENERAL}

ADVANTAGESWe can find out

the presence

& absence of a letter.

Durable & cost

effective.

Useful gadget for

home & offices.

Reduces human effort.

Time saving as

letter delivery proceeds

with faster pace.

REFERENCES• http://www.engineersgarage.com/electroni

c-circuits/electronic-letter-box• http://en.wikipedia.org/wiki/555_timer_IC• http://en.wikipedia.org/wiki/Photoresistor• http://circuiteasy.com/electronic-letter-box

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