Flexible design of the compact and light weight Travel Book Light presented here provides extra light for reading books, laptops and tablets. This circuit is ideal when traveling on the road or by air. It is realized using a Lithium-Ion (3.7V) battery, plus one White LED (1W). The whole circuit can be assembled on a very small (25x50mm) common/custom circuit board. Standard dimension of the commonly available 3.7V Lithium-Ion battery pack is 5.4 x 3.4 x 0.6 cm. Weight is near 23 gm.
Diagram of the LED Book Light is shown here. After the quick look, you may think that this circuit is filled with superfluous components. In fact those components are added intentionally to make the design more flexible. The preset pot (10K) can be used to control the intensity of the light output to some extent.
The power mosfet (STP60NF06) allows you to add more LEDs and/or drive the LED(s) from an external PWM signal. Note that BL-5CT Li-Ion battery for Nokia mobile phones can deliver 1050mAh of current at 3.7 Volts! Here is a Li-Ion battery charger circuit.
Since the white LED produces plentiful light for the purpose, no attempt is carried out to drive it very “hard”. The 1W white LED is selected only because of its compactness!