If you are traveling, you might need this device to charge your gadget along the way, since it is much cheaper to buy some standard AA batteries for backup than buying several rechargeable batteries of your gadget type. Below is a charger that more efficient than linear regulator like the “7805” while you are on the go. The most important component on this device is the “LT1301″. This is a small step up converter for to build switching mode power supplys with only a few external components. Below is the schematic diagram of the circuit:
To build this device, you need a LT1301 and a ic socket (8DIP), 2 electrolyte caps WITH! low ESR (6,3V 100uF), one inductor with a very LOW! DCR (around 0,03R) with 10uH should be able to handle switching currents at about 1,5 Amperes, one schottky rectifier like “SB130″ or “1N5817″ (important if you can’t get one of the two proposed rectifiers: low forward voltage drop, fast switching capability and it should be able to handle currents of 1 Ampere.), and A switch(on/off), an usb connector, a circuit board, a LED with resitor (limit led current to 2mA!, don’t loose your mA by pumping them through the LED) and don’t forget the battery holder.