The Digital Object Counter using LDR (Light Dependent Resistor) is a simple system that can be made into use for counting objects in the product manufacturing area of an industry, etc. Two IC555 are used in Monostable and Astable mode for respective pulse generation.

1. Digital Object
Counter
Team Members ( Group 12 ):
1. Aviral Srivastava (20BCE11027)
2. Anant Kumar (20BCE11035)
3. Athuldev Kp (20BCE11050)
4. Raghuveer Singh Chouhan (20BCE11055)
5. Krutarth Dubey (20BCE11056)
6. Vivek Singh Chuphal (20BCE11069)

2. Objective of the Project
• The objective of our project is to build
a working model of a digital object
counter.
• To Count the objects passing through
the predefine path

3. What is a Digital Object
Counter?
1) A counter machine is an abstract machine used in
formal logic and theoretical computer science to model
computation.
2) In more understandable way, it is a device which
calculates the number of objects fed to its sensor and
displays accordingly.
3) With the knowledge of IC’s (series 74), Light Dependent
Resistor (LDR) and other electrical components we have
created and build a digital object counter machine.
4) The main idea on which the circuit works is the
detection of absence of light by the Light Dependent
Resistor and displaying the output.

4. Circuit Diagram:

5. Components used with specifications
1) IC 7490 Decade counter.
2) IC 7447.
3) IC 555 Timer. - X 2
4) Common Anode 7 segment display.
5) Light Dependent Resistor (LDR). - X 1
6) Rheostat (Variable resistor) – 100k ohm
7) Resistors
8) Capacitors: 10 µF - X 2, 0.01 µF - X 1
9) Light Emitting Diodes (LED) - X 2
10) 6V Battery for power supply
11) Connecting Wires
12) Bread boards - X 2

6. Working Principle of the Project
Digital Object Counter machine mainly
has four units:
1. Primary sensing unit - L.D.R
2. Counting unit - Decade counter IC
7490
3. Binary to 7-segment display
conversion unit - IC 7447
4. Display unit - common anode
seven segment display.

7. Advantages of the Digital Object Counter Circuit
1. Very Low Power Consumption
2. Wide Supply Voltage Range
3. Good Noise Immunity

8. Drawbacks of the Digital
Object Counter Circuit
1. Loose connections while fabricating
on the bread boards
2. Problem with supplying the
required voltage to seven segment
display

9. Measures to overcome the drawbacks
1. It’s better to use a PCB rather
than a bread board
2. It’s better to use a voltage
regulator as supply rather than
a dc supply battery

10. Applications of the Project
1. Digital Clocks
2. Digital Cameras
3. Money Counting Machines
4. Walk through metal detectors
5. X ray baggage scanners

11. 1. IC 7490
• It is used as divide by 6 counter by
supplying pulse at input 1 and
grounding reset pins R3 and R4 and
connecting QA with input 2. 7490
IC can work like bi –quinary counter,
which is used to store decimal digits in
the form of 4 bit binary numbers.

12. 2. IC 7477
• That is the purpose of 7447 driver IC. It takes BCD inputs
and generates the 7 output lines for the 7 segment LED.
• The 74xx47 chip is used to drive 7 segment display. You
must use the 74xx47 with a common anode 7-segment
display (e.g. Kingbright part number SA03). The input to
the 74xx47 is a binary number DCBA where D is 8s, C is
4s, B is 2s and A is 1s. The inputs DCBA often come from
a binary counter.

13. 3. IC 555 Timer
• The standard 555 timer IC is used in a variety
of timer, pulse generation and oscillator
applications. It can be used to provide time
delays, as oscillators and as flip-flop elements.
The 555 timer IC is an integral part of
electronics projects.

14. Seven Segement Display
• A seven-segment display is a form of
electronic display device
for displaying decimal numerals that is
an alternative to the more complex dot
matrix displays. Seven-segment
displays are widely used in digital
clocks, electronic meters, basic
calculators, and other electronic
devices that display numerical
information

15. 5. 100k Variable Resistor
• This 100k ohm Trimpot is a type
of variable resistor in a metal
packaging, It can be easily mounted on
PCB and adjusted using screw driver.
Specifications:- Model Type : Metal
Preset. Resistance Value
: 100k ohm. Resistance Tolerance : 5%

16. 6. LDR
• Photo resistors, also known as light
dependent resistors (LDR), are light
sensitive devices most often used to
indicate the presence or absence of
light, or to measure the light intensity.
• LDRs have a sensitivity that varies with
the wavelength of the light applied and
are nonlinear devices.

17. References for the
Project
1) http://www.buildcircuit.com/digital-
object-counter/
2) http://en.wikipedia.org/wiki/Counter_
machine
3) http://www.buildcircuit.com/ldr-
engineer/
4) http://www.articlesnatch.com/Article/
A-Short-History-Of-The-Currency-
Counting- Machine/8179440

18. Screenshot of the Circuit: