CD4017, a 16-pin CMOS decade counter/divider, is a component of the LV-A logic family and falls within the 74LV series. It takes a clock signal from its input and sequentially activates the 10 outputs each time a clock pulse is received. This versatile IC, CD4017, finds extensive application in projects such as Light Chasers and Matrix Dies. It also serves various functions, including binary counter/decoder, frequency division, divide-by-N counting, and alarm systems.

To comprehend the operation of IC CD4017, a grasp of its pins is essential:

Input Pins:
a. Reset (Pin 15) – This pin resets the counter to zero. Connecting the fourth output to pin 15, the counter counts up to the third output and restarts from zero.

b. Clock (Pin 14) – The output is triggered when Pin 14 goes high. For the first clock pulse, pin 3 produces the output; for the subsequent pulses, pin 2, and so on. After ten pulses, it cycles back to the Q0 output.

c. Clock Inhibit (Pin 13) – This pin switches the counter "on" and "off." When pin 13 is high, the counter ignores clock pulses, preventing advancement. In this setup, pin 13 is grounded.

Output Pins (Pin Q0-Q9) – Sequential output reception, starting from pin 3.

Ground (Pin 8) and Supply (Pin 16) – Provide power and ground for the IC.

Carry Out (Pin 12) – Links multiple CD4017 ICs. In the circuit, this pin remains unconnected as only one IC is used.

Circuit Operation:

The counter initiates from zero upon pressing the switch, incrementing with each positive pulse at pin 14. The LEDs illuminate in sequence: LED2 for the first switch press, LED1 for the second, and so forth. Once LED4 illuminates, pressing the switch will not activate any LED as the counter counts to Q9 and resets (via a connection from pin 11 to pin 15).

Resetting the counter to zero upon circuit activation is achieved through C2 and R3, which toggle pin 15 high and low. A diode between pins 11 and 15 ensures the counter restarts by making pin 11 low and pin 15 high.

To counteract contact bounce that might generate multiple pulses, C3 and R4 introduce a short delay. This keeps pin 14 high until the switch is pressed again.

CD4017 Circuit Diagram

Project Components

• Capacitor
• Diode 1N4001
• LED
• Resistor

For more project details, check here.