Fork me on GitHub

Project Notes

#107 RingCounter

Test the classic CD4017 walking-ring counter

Notes

This is a classic circuit, often marketed as a hobby kit under various names like “water flow effect” or somesuch.

In fact, it is a straight-forward demonstration of the basic operation of the CD4017 Decade Counter/Divider with 10 Decoded Outputs:

  • a 555 astable oscillator provides a clock pulse to the CD4017
  • the CD4017 counts in the “1 of 10” cyclic manner
  • the CD4017 outputs directly drive a series of LEDs
  • so one LED will be on at a time

In this circuit, the variable resistor R1 gives control of the pulse frequency between 11Hz and 64Hz.

The circuit can be powered over a wide range - from about 4.5V to 15V, depending on the ratings of the specific chips. LED brightness will be affected by the supply voltage, and below 9V it might be desirable to replace the 1kΩ current-limiting resistors with a lower value. When powered by 9V battery source, the maximum current drawn is around 11.2mA.

Note that since only a single LED should be on at a given time, the 10 x 1kΩ current-limiting resistors could be replaced by a single resistor on a common cathode ground link for the LEDs. But it depends on the specific LED ratings, as this subjects all the “off” LEDs to a reverse voltage equal to the voltage drop across the resistor.

See RingCounterController for a variant of this project using an Arduino to control the 4017.

Interesting side-note: a very similar circuit is used in some SMD soldering training kits, such as this kit on aliexpress:

SMD kit

Construction

Breadboard

The Schematic

The Build

Credits and References

About LEAP#107 CMOS555 Timer
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.