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The Decade Counter.

The CD4017 DIP16 Decade Counter. Guess what the 'decade counter' does, it counts from zero to nine and then does it again with the appropriate clock input. Note that the output pins on the 4017 are numbered from zero to nine, which is 10 output pins. If you want theory I suggest you get on the WWW.

I have simplified the breadboard example by including only output zero for now so the hookup wires can be seen.

You will need:

  1. Breadboard
  2. One CD4017 IC
  3. 10 220 ohm resistors
  4. 10 LED 3.3V 20mA
  5. Lots of hookup wires

Breadboarding the 4017.

After getting the basic hookup done as above you can continue with the rest of the LED/Resistors. On the pinout diagram below you can see the pins of the 4017 numbered, don't confuse the pin numbers with the output's. For instance, pin one is output 5. Also notice here that pin 14 is the clock input where the output from the 555 astable will connect, you can see the red wire coming from there in the picture below.

4017 Pinout and Circuit.

Below you can see the completed breadboard. What a mess, huh? If you carefully hook output 0 to your first LED, and output 1 to your second LED, and so one they will blink on an off in a series.

4017 Light Chaser.

See the big red wire crossing over the whole mess and plugging into the buss that pin 14 is on? This is the clock signal coming from the 555 astable time built in the previous example. Continue to the Light Chase link at the top of this page to see the complete project.