CD4017 and NE555 Light Chaser Circuit

 Author:   Posted on:   Updated on:  2017-12-11T17:10:36Z
This is the classic circuit that uses NE555 timer and CD4017 counter to generate a sequence of pulses. If these pulses drive LEDs, a chaser can be built (also known as water flowing light). It can be used for entertainment purposes or for various light signaling. The following circuit uses 10 LEDs that turn on in a regular sequence. This is the maximum number of outputs. If you need less than 10 output channels, CD4017 features a reset pin that is connected to ground. The following output pin after the last used pin can be rewired to reset (after disconnecting it from ground). Thus, once the pulses sequence reaches the reset pin, CD4017 will start over again, limiting the number of output channels.

NE555 is configured as an astable multivibrator. Oscillation frequency is rather low for this application. It is determined by R1, R2+RV1 and C2. With the values used for this circuit, it can be adjusted between 10 and 65 Hz. The duty cycle is close to 50%. If you want to calculate it yourself, use this tool.
CD4017 and NE555 Light Chaser Circuit
The prototype I built is based on a kit. Soldering all those SMT parts was a challenge using ordinary soldering tools. But, in the end I succeeded. In the initial step, I soldered without caring about bridges between pads. Then, I removed excess solder using solder wick (braid). The result was a working circuit. Anyway, I'm still providing a PCB design that uses only THT parts. Here is the schematic.
CD4017 and NE555 Light Chaser Schematic
CD4017 and NE555 Light Chaser Schematic
The circuit can be powered from 3 to 15 V DC. If you want something bigger, CD4017 outputs can be connected to a transistor driver with the appropriate number of channels to drive higher current loads. Four outputs can be used even for driving a stepper motor (of course, with a driver). This is the PCB design.

CD4017 and NE555 Light Chaser PCB
CD4017 and NE555 Light Chaser PCB
You can download the PCB design as PDF from here. This one uses only THT parts that can be easily soldered. Don't forget the two jumpers near CD4017.

CD4017 and NE555 Light Chaser Turned On
CD4017 and NE555 Light Chaser Turned On
A short video with this circuit can be found on YouTube.

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