2B-Double Colored LED Running Light




By using Bi-Colored LEDs this project looks very pleasant and attractive.  By looking at glowing LEDs it appears as if red and green light is coming out of LED.  You can use this project for decoration and in business advertisement.  This project is small, simple and cheap.

Technical Description and Working System


This project  has been developed and tested OK in our TV Engineering Technical LAB.  The components and PCB used in our books are available for sale.  You can receive the project through post giving your order giving project code no.  The information about project code is given in the beginning and last pages in the books.  You can give your order through telephone.


In this project a very popular timer IC [NE555] and CMOS IC [CD4017] are used.  CMOS IC CD4017 is a decade counter.  IC NE555 is used as a astable multivibrator.  The low frequency clock pulse from this IC is given to the Sequential Decade Counter IC CD4017.  Pin no. 3 is the output pin of IC NE555.  The output of IC CD4017 changes in Sequential order depending upon each pulse received from output pin no. 3 of IC NE555.  The pin no. 11 & 15 of this ICs are connected together.  Due to this running light effect is produced.  The speed of running light can be changed with the help of VR1 [1ME] preset.

When speed is made high the LED seems to running both sides and from the

middle move back word.  At higher speed LEDs only twinkle.


Ten number of Bi-Colored LEDs are used in this project.  When LED no. 1 gives red light at that time LED no. 10 gives out green light.  The output pins of IC CD4017 are 3, 2, 4, 7, 10, 1, 5, 6, 9 & 11.   The position of LEDs are made clear in the diagram.  Thus at one time red and green light come outs from the LED according to the output pins.


The demonstration of lighting LEDs.


Output Pin     LEDs giving light together                Red LED        Green LED  3             D1             D10  2             D2             D9  4             D3             D8  7             D4             D7 10             D5             D6  1             D6             D5  5             D7             D4  6             D8             D3  9             D9             D2 11             D10            D1


Precaution While Making the Project


  1. Use IC base for CMOS IC. 2. Take care of the polarity of condenser connected at pin no. 2 of IC NE555. 3. Ground the middle pin of all LED. 4. As for as possible do not touch the CMOS IC with hand.