Seven Multi-Colour LED Fan / Wheel

A programmable LED fan displays required text, connecting LEDs in a straight line vertically and programmed to control the LEDs glow.  Then the LEDs are fixed to rotating frame on a DC motor for proper display of the text.


In our project, seven numbers of RGB (Red-Green-Blue) LEDs (Light Emitting Diodes) are used to display the text in multi-colour.  Four leads of each RGB-LED is connected to RED LED, GREEN LED, BLUE LED and COMMON in a single package.  The common may be connected to either all the 3 Anodes of RGB LEDs (Common Anode RGB) or all the 3 Cathodes of RGB LEDs (Common Cathode RGB).  We used Common Anode RGB LEDs in our project and all the seven LEDs are checked before soldering.

Since, we used seven LEDs with three colours per LED, we require 7 x 3 = 21 pins to control them easily and  directly.  So, we used 40 pin micro-controller, ATMEGA16A, which has 32 digital I/O pins.

A separate 5VDC power supply circuit board is made for the micro-controller, ATMEGA16.

The Full Circuit Diagrams for LEDs with micro-controller and 5V regulated power supply are is available here:


To have synchronizing the text on revolution, an A3144 Hall sensor is fitted on the rotating frame and connected to Interrupt (INT0)  of the micro-controller, ATMEGA16A.  A small magnet is fitted on the base plate below the Hall sensor with small air gap.  The text starts displaying whenever the ATMEGA16A receives interruption signal from Hall sensor due to magnetic effect.

The above main circuit board with 5VDC power supply is fitted on a frame with a hole to fix on a DC motor shaft. After fixing the main circuit board with 5VDC supply board and battery on the frame, then, the whole assembly has to be weight balanced.  The Main circuit board may be fixed in two ways (see the video). A 9V/12V DC motor may be used to rotate the frame.  To regulate the speed of the motor, a voltage regulator IC LM317 is used and its circuit diagram is available here:


Live as if you were to die tomorrow. . .     Learn as if you were to live forever.

– Mahatma Gandhi

click the link / attachment to download the file and rename as SevenMutliColourLedFan.HEX , then upload to ATMEGA8 using any suitable AVR programmer.

For source code (in C-language), (SevenMutliColourLedFan.C) please send message through contact formThe code will be sent to your e-mail.