letter box
TRANSCRIPT
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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