We often use CD4017 CMOS-IC when we want to build a 10 LED running light just for some fun or as a hobby.

Why do we use it?

The reason is that CD4017 is one of the most versatile counters.

For example, if it counts up to 10 and has 10 separate outputs, it will also +show a single output pin for each count from 0 to 9. This device is so functional that it contains the counter and the decoder section both making it very helpful.

It just can’t be understood simply by looking at it. You must learn about it properly by making many circuits using 4017 as shown below.

CD4017 CMOS-Decade counter/divider

This is also used to build all kinds of timers e.g. LED sequencers and controller circuits.

The figure below is a block diagram showing the inside of IC 4017 / HCF4017 . it will count with 5 D-type flip-flops.

Decoding and control are by 16 inverters and 15 gates.


Figure 1 block diagram inside CD4017 Pinout

To understand the importance of pins, take a look at the table below.


LM4017 Pinout

See the CD4017 pinout and function of each pin from the figure below.

CD4017 pinout

1). Pin 16 is a positive power supply and pin 8 is a ground connection.

The power supply ranges from 3 volts to 16 volts and the maximum power supply voltage does not does not exceed 18 volts.

2). Pin 13 has Clock enabled pins to control the clock.
When it is 0, the clock is enabled and the counter advances one count for each clock pulse.

When it is 1, the clock input is stopped and the counter does nothing even when the clock pulse arrives.

3). Pin 14 works when the clock triggers one count.

The clock pulse must be “clean” which means that its part must be lubricated.

If the clock is “noisy” the counter may advance two or more times during each clock pulse as the counter will count on the positive-going clock signal.

4). Pin 15 is the reset pin. Normally, it is “0”.

When it is turned to “1”, the counter is reset to “0”.

5.) Pins 1-7 and 9-11 are the decoded output pins.

The active count pin stays high and all others remain low.

The first LED1 has the first output and is labeled “0” as you will see later when the IC is used as a counter.

Also, in the 10LED, the output is normally LOW and goes HIGH in sequence and one LED will light at a time.

6). Pin 12 carries the output outside. It has the clock input of an additional counter or an external circuit informing that the count is complete.

How it works

I want to see you improve in Electronics learning. This can be done by using CD4017 well. Here is a step by step process that will make everything simpler for you.

Meet basic frequency divider

When a frequency of 10Hz is fed into the input pin 14, it is equally divided between the 10 outputs.

So, the first output or any other output will turn ON and OFF only once per second.

We can see that this chip can divide the frequency by 10. That’s why people often call CD4017 a decade counter/divider.

If you really want to use this function or any other frequency dividers, you must go on reading below.

Divide by 9 circuit using CD4017

Divide by 9 circuit CD4017

Output Buffer

Every output of CD4017 has a buffer which can drive an LED. This buffer gate is also present inside the IC but it does not involve external circuits. The falling waveform is also internal.

The cycle on its input indicates it achieves a low state during quiescent conditions. Changes to this low state are shown on the falling edge of the waveform.

Each output buffer of CD4017

Control Pins

Look at the following figure and learn with us.

Reset-clock inhibit-pin-4017

The counter circuit has 2 other important pins:

  • Reset pin
  • Clock ENABLE (Clock inhibit) pin

These are the control pins so they must be connected to either high or low pins. They must not be left floating around. This applies to the reset & clock inhibit pins too.

Reset Pin
When the reset pin is connected to a low voltage (Vss), the IC will count the full 10 outputs.

When we try to feed a voltage of above 2/3 VDD, for example if the VDD is 9V, it is 6V. It is a pulse of short duration into the reset pin. This will reset the IC to the first status. It is the output (pin number 3).

If we keep the reset pin set to high, the counter will still stay at pin 3.

Clock ENABLE pin
When we connect the clock enable (clock inhibit) pin to low status, the IC will count the full 10 outputs. This is explained above.

In contrast, when we connect it to a high status, the counter will freeze or restrain the output in operation.

In short, for that purpose we often connect pin 13 to ground.

Make stability control pins

Reset-clock inhibit-pin-4017

We should add R1 and R2 with the 100K to 1M resistor so that the spikes can be prevented from entering the control pins. While at the same time, the pin is given a high impedance path to any control voltages.

Even we use R1, R2 with a 1M resistor, the two pins will look like they are connected to VSS or to the ground because no current is flowing and hence there is no voltage across the resistors.

Frequency divider

What is more to learn? We should go back to learn how the CD4017 will divide by 9 or 8 or 6 or 5 or 4 or 3 or 2. See the diagram below.

Divide-by-9 Circuit

Divide by 9 circuit CD4017

Do you get the clear idea now? See next…

We connect the output number 10 to the reset pin which will make the counter count to 9 and then reset.

Divide-by-six Circuit

Divide by 6 circuit CD4017

Then, we connect 7th output to the pin 15 (reset). It will also make the counter count to 6 and then reset.


A divide-by-N circuit for the CD4017 requires the N + 1 output to be connected to the reset pin.

This circuit proves helpful for addition, divisions or for a circuit that requires easy alteration.

For standard division, a number of cheaper and better IC’s are also available.

How to Cascade the 4017 counter

We can cascade two (or more) 4017 counters to produce a single counter. See the circuit diagram, we use two 4017.

How to Cascade the 4017 counter

Ideally, it is a pre-set counter in which the outputs are diodes that are gated to a signaling device such as a lamp or bell.

We have arranged the circuit to create a forward reading display and any number of chips. More can also be added to increase the range.

Then, the carry-out pin 12 is connected to the clock in the next counter. The reset and clock inhibit pins must connect to ground (Vss).

The advantage of including the 100K resistors is that they allow a simple push-to-make switch. It can control the circuit for “reset” or “freeze”

10 LED flash using IC-4017

This is the circuit diagram of a light LED flash with a show of 10 LED.

This circuit uses an integrated number in circuit CD4017 to perform the Decade Counter/Divider with 10 Decoded Outputs.

10 LED flashing using CD4017

This is an integrated digital circuit CMOS. It uses the 9V power supply.

For a signal input, you must continue with the circuit that can produce general frequency which will use IC NE555 perfectly.

LED Chaser circuit using 555 and 4017

LED Chaser circuits using IC 4017 + IC 555
If you want to learn a basic digital system, you might find it difficult and boring.

Let’s try to create an LED chaser circuit which is much more interesting. It is used in computer games and in many scientific and mathematics applications.

So it is best for a beginner or for kids to learn about a digital system.

Also, my son loves them so I love it too. Continue Reading

Two way 12 LED running lights using 4017


If you want a new style in your home decor or just some beautiful lighting, this may be the perfect project for you. This shows two ways of LED running lighting. This is one of the 4017 project that uses 12 LED lamps that are arranged in 2 rows. Each row is of 6 LEDs. A green one and a red one, alternatively. You can use a different color of your choice.

0-99 counter using 2x LM4017 IC

If you want the counter circuit ranging from 0 to end at 99, I think this circuit maybe on the same wavelength as you for sure.

It uses an LM4017 decade counter/divider as shown in the circuit diagram below.

When a signal clock is fed at 14 pins, it will cause a position logic at a pin output. It will range from 0 to 99.

For switch S1, choose RUN or RESET.


Please see the circuit picture and improve your understanding.

We almost forget to mention the integrated number this circuit requires. It uses low voltage 3V to 15V power supply because it is IC digital CMOS.

10 Key Code Lock Switch Circuit

Key Code Lock Switch Circuit Using IC-4017

A simple Key code lock switch circuit uses IC-4017 digital with 10 switch bottom to control output by Relay. No microcontroller is as easier and cheaper as this one!

1 Hz Time base circuit using IC-4017

1 Hz Timebase circuit using IC-4017

We mostly need a standard digital clock of 1 Hz but our input signal is in square waveform of 10 Hz. We need to reduce it with digital frequency divider circuit to about 10 times lesser.
I suggest that IC 4017 (Decade Counter / Divider with 10 Decoded) must be used.

Bicycle distance meter circuit using 4N26, CD4017

The distance by using a bicycle wheel can be measured with this circuit.

The required circuit includes a few parts of normal electronic circuits. The important part included in it is a reed switch that detects a magnetic force of CD4017.

Bicycle distance meter circuit using 4N26,CD4017

The figure shows a Decade counter with 10 decoded outputs IC. It is then connected to Optocoupler 4N26, and displays a frequency counter.

2 Coin toss Game circuits diagram

Coin toss electronics using IC NE555-CD4017

Press Switch-S1, you will see the LED blink alternately. When the switch is released, S1 LED will stop showing Coin or Toss.

Automatic Day Indicator Circuit

The Automatically Day indicator circuit

The figure shows an Automatic day indicator circuit with an LED display for each day. This circuit uses the principal of light- turned on during the day due to the sunlight. To set an LDR-sensor, CD4017 acts as drive LED of 7 pcs for 7 days there.

Electronic dice circuit using CD4017

Electronic dice circuit using CD4017

The figure shows an image that looks like a real dice. We use only the press switch being thrown with 6 LED Display.

10 LED roulette circuits using TC4011-LM4017

The 10 LED roulette circuit using IC-4017 and IC-4011

They use the principles of digital ICs. It creates an integrated LED flashing following a rhythm which then stopps at one of the LEDs.

Enjoy creating a game and also gain knowledge from digital ICs.

Love Test Game Circuit using 8 LEDs

555 Sound effect generator circuit

This circuit would be a great starting point if you love music. It can be used to compose music for about 1000 tracks.

We will use an IC-555 timer and IC-4017 Decade Counter Divider with 10 Decoded.

Simple sound effect generator circuit using IC-555 and IC-4017

It also has the sound effect generator with adjusting tone music that has a tempo which becomes slow-fast as you want it with VR11. VR1-VR10 is used to adjust the tone according to need. More than 1000 tones can be adjusted.

LED Dancing light circuit with Music

The main features include a running light by changing the voice of the tiny microphone.

Led light movement the audio signal with LM358- IC 4017

In the circuit, we use 4017 to drive 10 LED display. LM358 which is a preamplifier and signal converter is also used along with a few general devices.

Besides 4017 on my website, there is also more stuff to explore.

10 step LEDs charger using IC 4017 only without PCB board

Amazing 4017 IC led chaser

Which is better? Which circuit would you like to build?

Have fun with the IC-4017.

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