I would like to construct a very thin and small (emergency) smart phone charger. For example, it would have enough power to boot the phone (let’s say a Samsung Galaxy Note 3) and power it, with GPS, for at least five minutes. I’d like the thickness to be not much greater than something like a 2032 button battery. Width and length are less critical than thickness.
I’ve thought about putting a number of the button batteries in series to get me 6-9 VDC, regulating the voltage, having a switch if needed, and outputting straight to a micro USB connector; with the whole assembly sandwiched between a couple strips of gorilla tape, plasti-dip, or similar. But how do I drop the voltage to 5.1 VDC and still keep it thin and SAFE for the phone? I’ve seen old posts about using a zener diode and a resistor, or using an LM7805. But I’ve also read where using the zener diode is risky for sensitive electronics (I don’t want to brick my phone) and it seems the LM7805 is thicker than what I want.
Are there existing thin regulator boards that I could use? Something off-the-shelf would be great. If not, what might I use to construct something as I’ve described?
Thanks in advance,
Andrew