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
- 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