After long time I'm posting on the blog, since I was busy with my works, I was unable to resist myself from putting this cute feature for our devices :
It's a good Pick:
Kyle Wengenroth, Electronics geek, has recently made this device using AVR Tiny85, since the code is not long enough for this project, we can use any of the small micro-controllers with lesser space in ROM, using this concept(PIC may be bulky(DIP) but it is also good).
The basic idea behind the circuit is to use a microcontroller as a timer controlling two transistors. When Kyle‘s circuit is power cycled, the timer inside an AVR starts, making a pin high, and when the timer is up, making the pin low again. This pin feeds into a PNP transistor which is in turn connected to a NPN transistor, creating a very tiny auto off circuit for anything with an SPST switch.
Download the Code,Circuit.
Have a Look :