A joule thief is a minimalist self-oscillating voltage booster that is small, low-cost, and easy to build, typically used for driving light loads.
It can use nearly all of the energy in a single-cell electric battery, even far below the voltage where other circuits consider the battery fully discharged; hence the name, which suggests the notion that the circuit is stealing energy or "joules" from the source. The term is a pun on the expression "jewel thief": one who steals jewelry or gemstones.
The circuit is a variant of the blocking oscillator that forms an unregulated voltage boost converter. The output voltage is increased at the expense of higher current draw on the input, but the integrated current of the output is lowered and brightness of a luminescence decreased.
You can DIY Joule Thief board very easy with 1 transistor and 1 resistant 1 k, wired coil, 1 battery cel 1v5