Two Digit Entry Counter

Two digit object counter

1.1

INTRODUCTION The objective of this project is to count the object passing on the

conveyor belt or the no of the person taken entry, automatically. In this modern world the machine are replacing the human labors. This is the circuit which makes the human being free from counting the no of object produced in the industry or in any other application. In short by using this circuit the human beings are made free from the tedious work of counting any no objects, as this circuit finds the application in the counting purpose. The counting purpose can be anything, either counting objects on the conveyor belt at the production level or counting the no of persons visited at the exhibition. Statisticians use special formulate to calculate the approximate number of people coming to and leaving a place at a given time. But none of these formulas can give 100% accurate and precise results. It is impossible to manually count the same. Now modern machines can do what men cannot. The circuit described here is meant to do just this very thing. The circuit can count up to almost ten thousand persons entering or leaving a place or can be use to count the number of articles passing on a conveyor belt (in a factory) etc. The circuit has unlimited application in almost all fields of industrialization. The counting capability can be increased to any numbers as per application. The complete circuit is based on popular timer IC 555 and CMOS IC 4033 and high quality LDR.

Institute of Technology, NU

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1.2 BLOCK DIAGRAM

7-S E GM E N T L E D D IS P LA Y

DECADE C OU N T E R

555 M ON OS TA B LE M U LT IV IB R A T OR

LD R R E C E IV E R

POW ER SU PPLY SOU R C E 9 VOLT BAT T ER Y


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2.1 CIRCUIT BLOCK DIAGRAM

P O W E R S U P P LY S OU R C E 9 V O LT B A T T E R Y

LDR R E C E IV E R

DECADE C OUN TER 2

7-S E GM E N T L E D D IS P L A Y2

DECADE C OUN TER 1

7-S E GM E N T L E D D IS P L A Y1

555 MO N O S TA B LE M U LT IV IB R A T OR


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2.2 DESCRIPTION DIAGRAM

OF

THE

CIRCUIT

BLOCK

The block diagram of the two digit object counter is shown in figure. The block diagram consists of the following section. •

LDR Receiver

•

555 Monostable Multivibrator

•

Decade Counter 1

•

Decade Counter2

•

Seven Segment LED Display 1

•

Seven Segment LED Display 2

2.2.1 LDR Receiver: A photo resistor or light dependent resistor or cadmium sulfide (CdS) cell is a resistor whose resistance decreases with increasing incident light intensity. It can also be referenced as a photoconductor. A photo resistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance.


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In this circuit the LDR is also used as an optical sensor. Whenever the object passes in between the LDR and the source of light, the light is interrupted due to presence of the object. This interruption of the light blocks the current to flow through it as the resistance of the LDR increases suddenly. This will make the pin no 2 of 555 IC at logic 0 for a moment.

2.2.2 555 Monostable Multivibrator: The 555 gets its name from the three 5-kohm resistors used in typical early implementations. The 555 timer is one of the most popular and versatile integrated circuits ever produced. Depending on the manufacturer, it includes over 20 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8).

Pin No

Name

Purpose

The 555 has three operating modes: 1 GND Ground, low level (0V) 2 TR A short pulse high → low on the trigger starts the timer 3 Q During a timing interval, the output stays at +VCC 4 R A timing interval can be interrupted by applying a reset pulse to low (0V) 5 CV Control voltage allows access to the internal voltage divider (2/3 VCC) 6 THR The threshold at which the interval ends (it ends if U.thr → 2/3 VCC) Institute of Technology, NU 7 DIS Connected to a capacitor whose discharge time will influence the5 8

V+, VCC

timing interval The positive supply voltage which must be between 3 and 15 V


•

Monostable mode: In this mode, the 555 functions as a "one-shot".

Applications include timers, missing pulse detection, bounce free switches, touch switches, Frequency Divider, Capacitance Measurement, Pulse Width Modulation (PWM) etc •

Astable: Free Running mode: the 555 can operate as an oscillator. Uses

include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation, etc. •

Bistable mode or Schmitt trigger: The 555 can operate as a flip-flop, if the

DIS pin is not connected and no capacitor is used. Uses include bounce free. Over here the 555 timer IC works in the Monostable mode. When the LDR sense the presence of the object and blocks the current which is reaching to pin no two of 555 IC, the pin is indirectly connected to logic 0. This will trigger the IC and since it is connected in the Monostable Multivibrator state it will give a pulse of 500 ms at the output pin i.e. Pin no 3 of the IC.

Monostable Mode: In the Monostable mode, the 555 timer acts as a “one-shot” pulse generator. The pulse begins when the 555 timer receives a trigger signal. The width of the pulse is determined by the time constant of an RC network, which consists of a capacitor (C) and a resistor (R). The pulse ends when the charge on the C equals 2/3 of the supply voltage. The pulse width can be lengthened or shortened to the need of the specific application by adjusting the values of R and C. The pulse width of time t is given by

which is the time it takes to charge C to 2/3 of the supply voltage. See RC circuit for an explanation of this effect.


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The relationships of the trigger signal, the voltage on the C and the pulse width are shown below:


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2.2.3 Decade counter 1 & 2: IC CD4033 is used as the Decade counter. Along with the Decade counter this IC is having the circuitry of the seven segment decoder. Hence to display the count of the counter we need not to use the separate seven segment decoder. The IC function dually as the Decade counter and the seven segment decoder.

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VDD 1

CLK

a

10

2

CLK INHIBIT

b

12

15

RST

c

13

14

LAMP TEST

d

9

CD4033

3

RIPPLE BLANK IN

e

11

4

RIPPLE BLANK OUT

f

6

g

7

5

CARRY OUT VSS 8

IC CD4033 consist of the 5 stage Johnson Decade counter and an output decoder which converts the Johnson code into the seven segment decoded output. The pin diagram of the IC is as shown in the above figure. •

Pin 1. is the clock input pin. Here the pulses that are to be counted are given. The counter advances to 1 count when the pulse at the clock pin goes from negative to positive transition, also in addition the clock inhibit pin should


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be kept low. When the pin 2. i.e. the clock inhibit pin is held high the counter advancement is stop through the pulses coming on the clock pin. •

Pin 2. is the clock inhibit pin. If the clock pin is continuously held high than the positive to negative transition of the clock pulse on the clock inhibit pin advances the counter by 1.

•

Pin 15. is the reset pin. When this pin is made high the counter reset and the count again start from 00.

•

Pin 3. and Pin 4. is the ripple blanking in and ripple blanking out pins. These pins together are used to blank out the insignificant zero in the integer or the fractional part. This will help to conserve the power and also it helps the user to easily read the data in the format of normal writing consistency.

•

Pin 14. is the Lamp test pin. This pin is used to check the working condition all the seven segments of the display. When this pin is held high, it overrides the normal decoder operation and put the seven outputs in the high state. This helps in detecting the actual cause of any malfunction.

•

Pin 5. is the carry out pin. This pin is connected to the succeeding IC’s clock pin when more than one IC’s are used. This pin will get an output pulse when the counter counts the 10 pulse i.e. from 0 to 9 and roll back to zero.

•

Pin 8. is the Vss i.e. ground and Pin 16. is the Vdd i.e. supply voltage.

•

Pin 10, 12, 13, 9, 11, 6, 7 are the decoder output pins i.e. a, b, c, d, e, f, g repectively.

2.2.4 Seven Segment LED Display 1 & 2:Two seven segment LED displays are used to display the count of the counter. Two display are connected to two different CD4033 IC.


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3.1 CIRCUIT DIAGRAM


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3.2 CIRCUIT DESCRIPTION & ITS WORKING There are three basic function unit of this circuit. These three units are LDR receiver, 555 timer IC and the IC CD4033 which is the combination of the decade counter and decoder. As shown in the circuit diagram the Light dependent resistor is used as an optical device. LDR is continuously exposed to the source of the light, hence the resistance of the LDR at all this time is almost zero and the current can easily flow through it. As current can easily flow through it , this will make the trigger pin of the 555 IC high continuously. But due to the presence of the object when the light is obstructed from falling on the LDR, the resistance of the LDR increases momentarily. This increase in resistance in the absence of the light is so high that it will obstruct the flow of current and thus will make the trigger pin of the IC 555 at the logic 0. Thus LDR detect the presence of the object and trigger the IC 555. Timer IC 555 is used as Monostable Multivibrator. Pin no 8 is connected to Vcc and pin no 1 is connected to the ground. Pin no 2. and pin no 6. i.e. trigger pin and the threshold pin respectively are directly connected to each other. Pin no 7. is the discharge pin which is connected to the resistor R17 and the resistor port P1. Pin no 5. is the charging voltage pin which is connected with the capacitor C1. Output pulse is obtained from the pin no 3. When the trigger pin is made to logic 0 due to the presence of the object, the IC is triggered and the capacitor connected at the pin no 5. starts charging through the threshold voltage


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available on the threshold pin. Threshold voltage is nothing but it is the Vcc. The capacitor charged towards Vcc. When the capacitor is fully charged it discharges through the Port P1. Thus the resistance of the port and the capacitance of the capacitor together decide the discharging time i.e. RC time constant of the capacitor. When the capacitor is fully discharge we get a pulse at the pin no. 3 i.e. output pin of the IC. The available pulse at the output pin is of approximately 500ms. The output pin of the 555 IC is directly connected to the clock pin of the IC CD4033 i.e. decade counter 1. The LED D1 is connected in between the output pin of 555 IC and the ground. Every time the pulse obtained at the output pin the LED glows. This helps us in knowing the proper working of the 555 IC in the Monostable Multivibrator mode. The resistor R16 is the current limiting resistor that protects the LED from high current. Pin no 1. of the CD4033 IC is the clock pin. Also it is connected to the output pin of the IC 555, from where it gets the pulse. Pin no 8. and pin no 2. is the Vss and Inhibit pins of the IC. Both are connected to the ground. Since Inhibit pin is connected to the ground the negative to positive transition of the incoming pulse on the clock pin advances the counter by 1. Pin no 16. and pin no 3 are the Vdd and RBI pins of the IC. Both the pins are connected to the supply voltage. Since RBI is connected to the Vcc it will blank the insignificance zero of the display. This helps in power conserving and also it becomes easy for the user to read the display. Pin no 15. and pin no 14. of the IC are the reset pin and the Lamp test pins. These two pins of both the IC’s is connected to ground normally. Also they are connected to supply voltage through push button switch. When we want to rest the counter the push button switch is pressed once and hence the Reset pin is connected to supply voltage i.e. logic 1. This will make the counter to reset and start counting from 00. Also along with the Reset pin the Lamp test pin of the IC is connected to the Vcc when the push button switch is pressed. This will roll over the decoder action and will send high to all the seven output pins. This helps in testing the working condition of all seven segments.


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Pin no 5. is the clock output pin of the IC 4033. This pin of the decade counter IC 1 is connected to the clock pin of the decade counter IC 2. Hence every time the counter of the IC 1 counts the 10 pulses i.e. 0 to 9 and rolls back to 0, it give a pulse on this pin no 5 and hence the clock pin of IC 2 gets the pulse. Thus we can say that after every ten advancement of the counter 1, the counter 2 advanced by 1. Pin no 10, 12, 13, 9, 11, 6, 7 are the decoder output pins i.e. a, b, c, d, e, f, g respectively.

Each pin of both the IC’s is connected to the respective

segments of the display through the resistor. These resistors are the current limiting resistors which protect the individual segments of the display from getting damage. Over here since the IC 1 is connected to the display 1 it acts as LSB and display 2 acts as MSB.

4.1 LIST OF THE COMPONENTS


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SR. No. 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17

Description

Number

General purpose PCB (large size) Resistor (R1 to R14) --- 220 Ohm, ¼ watt Resistor R15 --- 10K Ohm, ¼ watt Resistor R16, R17 --- 1K Ohm, ¼ watt Resistor R18 --- 100K Ohm, ¼ watt Variable Resistor P1 --- 10K or 20K or 50K Capacitor C1 --- 0.01 micro F, ceramic disk IC CD4033 --- U1, U2 (Decade counter) IC 555 --- U3 (Timer IC) Common Cathode SSD --- DS1, DS2 (LT543) LDR --- D2 Micro Switch --- S1 LED --- D1 IC socket --- 16 pin IC socket --- 8 pin Battery Snap Battery 9 volt

1 14 1 2 1 1 1 2 1 2 1 1 1 2 1 1 1


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5.1 ADVANTAGES •

Since the circuit operates totally on digital concept the noise interference is minimum.

•

As it does not use big heat sink and power transistor, the design is compact and can be fixed in small box.

•

•

Consumes less power.

•

Offers less Electro Magnetic interference (EMI) Integrated chip 555 and CD4033 is energy efficient circuit, so it is

environmental friendly.


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5.2 DISADVANTAGES

•

The circuit used the Seven segment display which consumes more power.

•

The current version of the circuit can not sense the object in the day light.


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5.3 LIMITATION •

There is limitation to the no of the object that the circuit can count. The current version of the circuit can count only 00 to 99. So it can not be used at the places where more no of counts are required.

•

Since efficiency of LDR used in the circuit is very low. So there are chances of miss readings.


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5.4 APPLICATIONS

•

News Paper Industries: The project can be used in the news paper industries to count the no

of the papers published. •

Pharmaceutical and Dairy industries: Both type of industries uses this kind of circuit to count the no of the

filled bottles or the strips of the tablets.

•

Exhibition center: It is used at the exhibition center to count the no of persons that have

visited the exhibition. Institute of Technology, NU

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•

Also it has found its application in the office automation system.

5.5 SCOPE OF THE FUTURE ENHANCEMENT

•

More number of the decade counter IC CD4033 can be used to increase the no of count. For example if we use three IC’ s count increase to 1000.

•

Instead of the LDR we can use photo transistor to increase the accuracy and efficiency of the system.


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5.6 CONCLUSION The even objective of the project is “Two digit object counter” that has been successfully achieved.

The project is also scalable foe several

improvement as stated in future enhancement in the chapter 10.5.


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5.7 COST OF THE PROJECT


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SR. No. 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17

Description

Number

Cost

General purpose PCB (large size) Resistor (R1 to R14) --- 220 Ohm, ¼ watt Resistor R15 --- 10K Ohm, ¼ watt Resistor R16, R17 --- 1K Ohm, ¼ watt Resistor R18 --- 100K Ohm, ¼ watt Variable Resistor P1 --- 10K or 20K or 50K Capacitor C1 --- 0.01 micro F, ceramic disk IC CD4033 --- U1, U2 (Decade counter) IC 555 --- U3 (Timer IC) Common Cathode SSD --- DS1, DS2 (LT543) LDR --- D2 Micro Switch --- S1 LED --- D1 IC socket --- 16 pin IC socket --- 8 pin Battery Snap Battery 9 volt

1 14 1 2 1 1 1 2 1 2 1 1 1 2 1 1 1

40 21 01 03 02 10 02 100 20 20 10 08 05 05 05 05 15 Total = 272


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6.1 REFERENCES Books: •

Fundamentals of Digital circuits By, Anand kumar

•

Electronics Devices & circuits vol. 2 By, A. P. Godse

Websites: •

www.atmel.com

•

www.semiconductor.philips.com/products/standard/microcontroller

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www.google.com

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www.alldatasheet.com

Other Material: •

Datasheet of the 555 timer IC

•

Datasheet of the IC CD4033


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Two Digit Entry Counter

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