seven segment display 1

2 Digit Digital Object Counter

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2 Digit Digital object counter 

Here is the circuit Diagram Of the Door Entry Person Counter project, This object counter circuit is used as a Digital Object Counter using a Two Digit Seven Segment LED Display.

This can also be called People or Object counter Circuit diagram using IC 555 and IC 4033 or Digital IR Counter to Count Door Entries.

Here 4 IC used 0ne Comparator LM358, One Timer ic LM555, Two Ripple Counter IC 4033

This can be used at door for counting the no. of person, no. of products etc that is entering into any room/office through a dedicated path or particular Door.

Operation is Done using Interruption Of the IR light Between Photodiode and IR LED. IR LED Emits Infrared ray which is incident on Photodiode. When this light interrupted by any person or object .

2 digit Digital object counter circuit


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Object counters or product counters are important applications used in industries, shopping malls, etc. They count objects or products automatically and so reduce human efforts. In this project, I am introducing a simple object counter circuit without using any microcontroller.

Two 7  Segment Decoder ic CD4033 is used for showing the numeric value through two 7 segment LED display. two common cathode seven segment display units are connected with 7 segment decoder IC.  A 555 timer IC is used to generate a pulse for triggering the seven-segment decoder (CD4033).  555 timer IC is configured in a mono-stable mode for generating pulse. 

The input signal From IR sensor is compared by the Comparator IC LM358 Which is used to compare the input signal to which is high or Low.  And according to input signal of the non-inverting pin of comparator after comparing with V(ref) ie inverting input. 

If Vin <V ref then output is High(+)

IfVin > V ref then output is Low(-) .

When Output is low of comparator then Timer 555 is triggered through the negative pulse of comparator output is given on pin no 2 of 555 ic.


For more Detail About comparator working please click here which is described in another project. Door Security Alarm System

IR LED– IR LED is a Type of LED That Emits Infrared Light and infrared light is not visible by Human Eye. This IR Ight/radiation activates the PHOTODIODE.

PHOTODIODE– A photodiode is a PN-junction diode that consumes light energy to produce an electric current. These diodes are particularly designed to work in reverse bias condition, it means that the P-side of the photodiode is associated with the negative terminal of the battery and the n-side is connected to the positive terminal of the battery.  When light falls on the diode it changes light into electric current. photodiode

When photons of energy greater than 1.1 eV hit the diode, electron-hole pairs are created. The intensity of photon absorption depends on the energy of photons – the lower the energy of photons, the deeper the absorption is. This process is known as the inner photoelectric effect.

CD4033–  CD4033B consist of a 5-stage Johnson decade counter and an output decoder which converts the Johnson code to a 7-segment decoded output for driving one stage in a numerical display. It converts the input into numeric display which can be seen on 7 segment display or with the help of LEDs. This IC is widely used in 7 Segment decimal display circuits, Frequency division 7 segment displays, Clocks, Timers etc.

cd4033 counter decoder pin

4033 decoder

The clock input of CD 4033 is highly sensitive and can detect the e.m.f from the atmosphere or the static charge from the fingertip. It has 7 decoded outputs. A High pulse in the Reset pin clears the counter to its zero count. The Counter advances one by one with each positive Clock signal in its input when the clock inhibit pin is held low. When the Clock inhibit pin gets a high pulse, the Counter advancement will be inhibited. To ensure proper counting sequence, an Anti clock gating is provided in the Johnson counter. The Carry out pin signal completes one cycle for every 10 clock input cycles and this pin is used for cascading more ICs. The 7 decoded outputs a to g illuminates the proper segments of the 7 segment display to represents the digits 0 to 9.

Ripple blanking makes only one Zero to be displayed while all other Zeros remains blanked in multi-segment displays. For this, the IC has a Ripple blank input (RB In ) pin 3 and Ripple blank Output ( RB Out) pin 4.

For example in a Calculator, there are normally 8 displays. But it shows only one 0 and not 00000000.If the Ripple blank input is activated, the first chip will send a blanking signal to the RB In of the second chip to blank the display. The second chip will send the signal to the third chip and so on. For example to show the number 4012 in an 8 segment display, the chips will attempt to display 00004012. If Ripple blanking is activated, the first four chips will blank the four zeros and the 4th chip will not send a blanking signal to the blanking input of 5th chip. So the digit 4012 will be displayed. This is called Ripple blanking and it improves the readability of the display and is the most common feature of calculators.

Lamp test ( Strobe) pin 14

It is used to test whether all the segments of the display are working or not. This pin is active low at logic level 1.To enable the lamp test feature; momentarily bring the pin14 to ground. This will illuminate all the segments of the 7 segment display.It should be connected to ground in normal operation.

Carry out pin 5

The Carryout pin signal completes one cycle for every 10 clock input cycles and this pin is used for cascading more ICs.

Clock Inhibit pin 2

The counter advances one by one with each positive clock signal in its input when the clock inhibit pin is held low. When the clock inhibit pin gets a high pulse, the counter advancement will be inhibited.

Download CD4033B Datasheet 

The 7-segment display consists of seven LEDs (hence its name) arranged in a rectangular fashion as shown. Each of the seven LEDs is called a segment because when illuminated the segment forms part of a numerical digit (both Decimal and Hex) to be displayed. An additional 8th LED is sometimes used within the same package thus allowing the indication of a decimal point, (DP) when two or more 7-segment displays are connected together to display numbers greater than ten.

7 segment led

Each one of the seven LEDs in the display is given a positional segment with one of its connection pins being brought straight out of the rectangular plastic package. These individually LED pins are labeled from a through to g representing each individual LED. The other LED pins are connected together and wired to form a common pin.

The displays common pin is generally used to identify which type of 7-segment display it is. As each LED has two connecting pins, one called the “Anode” and the other called the “Cathode”, there are therefore two types of LED 7-segment display called: Common Cathode (CC) and Common Anode (CA).

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LM358 IC – 1

555 timer IC -1


150 Ohm – 2

CD4033 -2

10K resistor -2

100K resistor -1

10K POT -1


100uF capacitor -1

0.1uf capacitor – 1

IR sensors-1

LED -1

Common Cathode 7-Segment Display (Two-digit)-1 Or One digit- 2


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