correctly configured, your computer will go into sleep mode when left unattended for a long sufficient time. So will your cell phone, as well as just about every other piece of sufficiently complex electronics. much easier circuits, though, are left at the mercy of a SPST switch; if you fail to remember to turn a flashlight off, it will be dead next time you requirement to utilize it. wanting an auto-off circuit easy electronics, [Kyle] threw together this car shutoff circuit.
The fundamental concept behind the cirucuit is to utilize 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, as well as when the timer is up, making the pin low again. This pin feeds into a PNP transistor which is in turn linked to a NPN transistor, producing a extremely small car off circuit for anything with an SPST switch.
[Kyle] states there are a few enhancements to be made – utilizing MOSFETS to deal with higher currents as well as potentially utilizing a smaller microntroller like an ATtiny 4/5/9/10 to shrink the circuit’s volume. It’s a excellent idea, bringing the concept of a flashlight with car shutoff into reality.