This circuit uses the self-oscillating properties so the output voltage is increased at the expense of higher current draw on the input.
Step 1: Materials
A Standard transistor
(Capacitor is optional) But the the output will be more steady
Step 2: Follow the Schematics on the Last Step
You don't need any soldering. Just follow the schematics and twist the wires in place.
Now you can use the rest of the battery life with a dead battery.
You can also place this in your electronics to help pull out the remaining bit of electricity that is stored within the battery.