Twinkling LED Christmas Star


Xmas is just round the corner, and this is the right time to build your own festival lights using LEDs. Presented here is a simple LED-based Xmas light/star circuit which can be constructed using inexpensive components. At the heart of this battery operated circuit is a tiny microcontroller PIC12F675 (IC1). Here, brightness and oscillation of the white LEDs (LED1-LED6) are digitally controlled using Pulse Width Modulation (PWM) signal generated by IC1. The trick of using a random number generator for light modulation will create a credible simulation of the sparkling starlight.

Twinkle Christmas Lights Schematic

Twinkling LED Christmas Star Schematic

Notes:

  • Can be powered from any regulated/unregulated 9V dc supply source
  • For compactness, replace IC2 (LM7805) with 78L05 available in TO92 package
  • Each output pin of the IC1 is limited to source or sink only 25mA of current
  • BS170 (T1) can handle a maximum current of 500mA
  • White LEDs are used deliberately. It is easy to convert white light into different colors (using additional stuff like LED caps)

Due to commercial reasons, I am not able to include the source code (written in C) here. However tested hex code can be downloaded from my Google Drive Account: Click here to download: http://goo.gl/jf8tJK


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