4017 LED Chaser (Knight Rider Light)

Circuit Diagram

How to Build It

1. Place the NE555 (as the clock oscillator) and the CD4017 (as the counter) on the breadboard.
2. Configure the NE555 in astable mode, with its output (pin 3) feeding the CD4017's clock input (pin 14).
3. Connect the CD4017's pin 16 (VCC) to the positive rail and pin 8 (GND) to negative — check the datasheet for exact pin numbers.
4. Connect an LED (with a limiting resistor) to each of the CD4017's first four outputs (pins 3, 2, 4, 7).
5. Connect pin 15 (RESET) to GND for continuous counting.
6. Power the circuit — the LEDs should light up one at a time, in a repeating sequence.

Bill of Materials