If you ever come across an electronic component that looks like this (a small electrolytic capacitor or radial inductor) with simply the letters “HDX” and rattles if you shake it (even a little bit) then I’ll save you some trouble. It’s called a “vibration switch”! And, as you might guess, it’s a SPST switch that closes it’s contacts when it senses vibration. These are not as sensitive as a G-Force sensor but they can do the trick in telling something when it’s being picked up or moved around.
I needed a power supply that could give out enough peak current to power at least three Raspberry Pi 2s. Just idle one Raspberry Pi 2 can draw almost 500 mA but at peak processing speed one can draw around 2 Amps at 5V. I didn’t want to have to have three “wall warts” so I sat down and did some research on the internet and designed the circuit below. With proper heat sinking on the 2N3055 power transistor it should allow for a peak of almost 7 Amps at 5V.