A Decade Counter using 555 and 4017 IC's

Authors: Ekundayo Toheeb Dayo, Anumbor Ogor

Introduction

A decade counter has ten outputs which go HIGH in sequence when a source of pulses is connected to the CLOCK input and when suitable logic levels are applied to the RESET and ENABLE inputs (doctronics.co.uk, 2009).                

Internally, the 4017 decade counter contains five bi-stable sub-units. These are interconnected in a pattern known as a Johnson counter. The outputs of the bi-stables are decoded to give the ten individual outputs.

Objectives 

The aim of this project is to design a decade counter using a 555 timer astable configuration. The objective is to design a 4017 decade counter to drive higher currents loads, so it is OK to connect LEDs with series resistors directly to its outputs.

To see the 4017 in action, you need to build it in an astable configuration.

Bill of Material(s)
S/N	Components	Piece(s)
1.	555 Timer	1
2.	4017 decade counter	1
3.	330 ohms	10
4.	Jumper wires	20
5.	Led	10
6.	Capacitor(470 micro Farad)	1
7.	Resistors (1 k ohms)	1
8.	Battery (Power Source) – 9v	1
9.	Breadboard	1

Decade Counter block diagram

The output of the 555 timer goes in has the clock input of the 4017 decade counter. Next, the outputs of the 4017 counter is connected to a Resistors each and finally the second terminal of resistor connected to  each of the Leds.

NOTE: Pulse repetition frequency (PRF) is the number of times a pulsed activity occurs every second. This is similar to cycle per second used to describe other types of waveforms. PRF has a pulse period, which is the time between pulses.

                                                            T = 1/PRF

The Time interval for the Led to goes OFF and ON is important for this particular project, so we need a p.r.f value; based on that, design your 555 timer using the resistors and capacitors.

Given that the pulse repetitive frequency (p.r.f) = 1.44/ [C(R1 + 2R2)]

According to doctronics.co.uk (2009) , the specifications for astable configuration:

C = 10 nF – 470 nF

R1 = 1k ohms - 1M ohms

R2 = 1k ohms - 1M ohms

Where C is the capacitor and R is the resistor

For this particular project and design the Pulse Repetition Frequency is approximately 1 Hz and the Time, T is 1 second. 

See workings below:  p.r.f = 1.44/ [470 x 10^-6(1000 + 2(1000))]

                                                    = 1.44/1.41

                                         p.r.f = 1.02 (approximately 1Hz)

                Hence, the time, T = 1/1                  = 1second

Implementation and Set up

Using the Proteus 8 Professional ISIS software, as a simulating tool for this project, we have the below schematic diagram, before finally implementing on the breadboard preferably.

Schematic for Decade Counter

Connection Steps

- PIN 1 to Ground Railings, PIN 8 to Vcc Railings

- PIN 4 (RESET) is connected to Vcc

- PIN 2 (Trigger) using a Jumper wire to PIN 6 (Threshold)

- Connect one terminal to Resistor, R1 to + of Vcc Railings

- Connect the other terminal of R1 to PIN 7(Discharge)

- Connect one terminal of Resistor, R2 to PIN 7 (Discharge)

- Other terminal of R2 is connected to PIN 6 (Threshold)

-Connect the electrolytic capacitor, + terminal to PIN 6 and – terminal to Ground Railing

- The output of the 555 timer is connected to PIN 14 of the 4017 decade counter as the clock input to drive the decade counter.

- Connect PIN 13 and PIN 15 of the 4017 counter to Ground

- The ten (10) outputs from the decade counter is connected to a 330 ohms Resistor each

- Connect the anode of each of the LEDs to the other terminal of each of the Resistors (330 ohms)

- All the cathode of each of the LEDs is connected to the Ground.

Conclusion and Recommendations

 

The project shows how to implement a decade counter and turning the LEDs in sequence from 0 – 9. The Proteus ISIS is a good simulating tool for designers because it gives you the ability to to run projects and make crucial design-decisions before implementing it on a breadboard or printed circuit board.

Also, the 4017 decade counter IC is an extremely useful device and it is used in the Games Timer and in various construction kits including the Light Chaser and the Matrix Die. It can be used to generate a traffic light sequence.

References

http://www.doctronics.co.uk, 2009, Date Accessed: April 29, 2016, 2.05am.

https://www.herculestechnology.blogspot.com, Date Accessed: April 15, 2016, 5.30pm.