0 Simple LED Flash Light

Small flash light uses 3V battery and 3V bulb. The problem with ordinary bulb is it consumes more power than the light it produces. Better flash light (torch) this time uses LED as the replacement of the conventional bulb. Using high brightness LED solves the power consumption problem, but the challenge now is how we can light up a high brightness LED using 3V battery since it requires more than 3V to start emitting light. The circuit configuration is very similar to two transistor flasher circuit. This simple circuit is steps the voltage up via transformer Tr to make the LEDs light up.

LED flash light circuit

NPN transistor pinout

Part List:
R1, R2 - 3.9 kilo ohms 1/4W
R3 - 22 ohms 1/4W
C1, C2 - 100nF mylar or ceramic capacitor
D1 - 1N4001 or similar diode (germanium type the better)
Q1, Q2 - 2N2222, 9013 or similar NPN transistor
Tr - any hand wound transformer ratio 1:3
LED - 2 white or any high brightness LED (see LED pinout)
DC - 3V battery (2 x AA cell)

Transformer:
You can buy a small transformer atleast 1:3 number of turns ratio or make one by just using an antenna bar or toroid core salvaged from an old cfl. Pins 1 and 2 are connected to the collector and battery source while 3 and 4 to the LEDs. Winding 1 to 2 is 10 turns #22AWG magnetic wire while 3 to 4 is 32 turns #26AWG wire.

transformer

Similar Circuits:
1.5V LED driver - can be used as torch and powered by 1.5V
LED light phototheraphy circuit - used for theraphy
Joule Thief - can be used even using "dead batteries"