1 1.5V LED driver using transistor

1.5V cell cannot light up led since it requires around 1.8V to 3.8V as forward voltage. This simple circuit will help us drive  LED using only 1.5V or even 1.2V cell.

Part List:
1-1.5V cell
1-1N4007 or any similar diode
1-2N2222 transistor or any similar NPN transistor
1-1.2k-ohms  resistor
1-220-ohms resistor
1-white LED or any bright LED
    *see LED pinout if you are not sure with LED pins

Circuit schematic and parts:

LED driver schematic

Ferrite core and transistor pins

Winding the  coil and making the ciruit :
First  look for any magnetic core for your coil. Toroidal ferrite core from old cfl is recommended (see diagram above) but still you can use any magnetic core available at hand. Using #22AWG magnetic wire wind it 30 turns and mark the starting as 1, center-tap as 2 and ending of the winding as number 3. Follow the led driver schematic above and its done.

Note: You can remove diode 1N4007 and 220 resistor and replace it with another LED. Their main purpose is mainly for suppressing excessive voltage that can damage the LED. Another similar and much better driver is the light activated led driver (joule thief) which is also powered by 1.5V cell.