Sequential LED Flasher with 555 Timer and 4017

Introduction

The 555 timer IC can be used to create a sequential LED flasher circuit by combining it with a 4017 Decade Counter. This setup allows us to flash multiple LEDs in sequence, making it useful for visual indicators or lighting effects. The 555 timer generates clock pulses, which are sent to the 4017 to drive the LEDs in order.

Objective

The objective of this experiment is to create a circuit that flashes multiple LEDs in sequence using a 555 timer and a 4017 Decade Counter.

Components Needed

1 x 555 Timer IC
1 x 4017 Decade Counter IC
10 x LEDs
10 x Resistors (220Ω)
1 x Resistor (R1)
1 x Capacitor (C1)
1 x Breadboard
Connecting Wires
Power Supply (5V)

Circuit Diagram

Procedure

Connect pin 1 (GND) of the 555 timer to the ground of the power supply.
Connect pin 8 (VCC) of the 555 timer to the positive supply (5V).
Connect pin 4 (Reset) to VCC to disable the reset feature.
Connect pin 7 (Discharge) to the junction of R1 and pin 6 (Threshold).
Place a capacitor (C1) between pin 6 and ground.
Connect a resistor (R1) between pin 6 and VCC.
Pin 3 (Output) of the 555 timer should be connected to the clock input (pin 14) of the 4017 Decade Counter.
Connect pin 16 (VCC) and pin 8 (GND) of the 4017 to the power supply and ground, respectively.
Connect the output pins (pins 0 to 9) of the 4017 to the LEDs through 220Ω resistors, and ground the other side of each LED.
Each clock pulse from the 555 timer will advance the 4017 counter, sequentially turning on the LEDs one by one.
Power the circuit and observe the LEDs flashing in sequence as clock pulses are generated.

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Results

When the circuit is powered, the LEDs will light up sequentially, one after the other, based on the clock pulses generated by the 555 timer. The speed of the flashing can be adjusted by changing the values of R1 and C1, which control the frequency of the clock signal.

Conclusion

In this experiment, we created a sequential LED flasher using the 555 timer and a 4017 Decade Counter. This circuit is useful for visual displays where LEDs need to light up in a sequential order. By modifying the timing components of the 555 timer, the speed of the flashing can be controlled, making this circuit suitable for a variety of LED-based projects.