Introduction
The CD4017 is a decade counter that can drive LEDs in a sequential pattern, commonly used in running light displays. In this experiment, we will use the CD4017 to build an LED sequencer that lights up multiple LEDs in sequence, driven by a clock signal from a 555 timer.
Objective
The objective of this experiment is to use the CD4017 decade counter to create an LED sequencer where the LEDs light up in sequence, simulating a running light display.
Components Needed
- 1 x CD4017 Decade Counter IC
- 1 x 555 Timer IC (for clock signal)
- 9 x LEDs (different colors can be used)
- 9 x Resistors (220Ω for each LED)
- 2 x Resistors (10kΩ and 1kΩ for the 555 timer)
- 1 x Capacitor (10µF for the 555 timer)
- 1 x Breadboard
- Connecting Wires
- Power Supply (5V)
Circuit Diagram
Procedure
- Connect pin 8 (GND) of the CD4017 to the ground of the power supply, and pin 16 (VCC) to the positive voltage supply (5V).
- Connect pins Q0 to Q8 of the CD4017 to the anodes of 9 LEDs, each in series with a 220Ω resistor. The cathodes of all LEDs should be connected to ground.
- Configure the 555 timer to work in astable mode to generate a clock signal for the CD4017:
- Connect pin 1 (GND) to ground and pin 8 (VCC) to 5V.
- Connect pin 2 (TRIG) to pin 6 (THRESH).
- Connect a 10kΩ resistor between pin 7 (DISCH) and VCC.
- Connect a 1kΩ resistor between pin 7 (DISCH) and pin 6 (THRESH).
- Connect a 10µF capacitor between pin 6 (THRESH) and ground.
- Connect the output (pin 3) of the 555 timer to the clock input (pin 14) of the CD4017.
- Optionally, connect pin 15 (RESET) of the CD4017 to ground to prevent the counter from resetting prematurely.
- Power the circuit. The LEDs will light up sequentially, with each LED turning on after every clock pulse from the 555 timer.
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Results
Upon powering the circuit, the LEDs will light up one by one in sequence, creating a running light display. The speed of the sequence can be adjusted by modifying the frequency of the 555 timer's output clock signal.
Conclusion
In this experiment, we successfully used the CD4017 decade counter to create an LED sequencer, demonstrating its use in controlling multiple LEDs in a sequential pattern. This setup is commonly used in various light displays and offers a simple yet effective way to sequence outputs in digital electronics.
