The CD 4017 is called a COUNTER or DIVIDER or DECADE COUNTER. It is a very handy chip for producing “Running LED effects” etc.
It has 10 outputs. Output “0” goes HIGH on the rise of the first clock cycle.
On the rise of the second clock cycle, output “0” goes LOW and output “1” goes HIGH. This process continues across the ten outputs and cycles to output “0” on the eleventh cycle.
The ”Carry Out” pin goes LOW when output “5” goes HIGH and goes HIGH when output “0” goes HIGH.
When RESET (pin 15) is taken HIGH, the chip will make output “0” go HIGH and remain HIGH.
When ”Clock Inhibit” (pin 13) is taken HIGH, the counter will FREEZE on the output that is currently HIGH.

• The CD 4017 is a divide-by-10 CMOS chip.
• Minimum supply voltage 6v
• Maximum supply voltage 15v
• Max current per output 15mA
• Maximum speed of operation 5MHz

The animation below shows how a CD 4017 works. It will count every time the voltage at pin 14 swings from low to high, provided pin 13 is low and pin 15 is not high. Click the power switch to start the action! You can click the Enable line to see what happens and the Reset line.

Circuits built around a CD 4017:

SCANNER circuit above illuminates one of the ten LEDs at a time.

KITT SCANNER scans back and forth across the 6 LEDs.