Instructables
Using the basic Solar charger developed here, we can build a very simple and effective reading light. Bright enough to light a small room, it is more than bright enough to work by, and a day's recharging is all it needs to provide over 2 hours of use. 

A garden-variety solar cell (2-volt, 20mA) is all that's needed, and the entire circuit consists of ten basic components.
 
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Step 1: The Parts List

The  components required are:

BC327 PNP transistor
BC337 NPN transistor
1N914 or 1N4148 Low power signal diode
10K resistor
5.6-ohm resistor
100uF 6v capacitor
330pF capacitor
100uH inductor (A larger can-type is chosen for its lower internal resistance. Thanks to acmefixer for bringing this up!)

1 x Red LED 20mA
1 x White LED 100mA. A wide angle unit (90-degrees or more) is recommended here to avoid glare and hot-spots. I also chose the piranha style so I can get the 90-degree angle when I assembled it.

Connecting and Mounting hardware.

Step 2: Assembly

 The simplicity of the circuit allows almost any method to put this together. I used a copper-padded perf board and I've included the wiring layout below. Remember the first view is from the component side and the second is a mirror image of the first.

Allow the space but do not solder the transistors till the very end to avoid any heat damage to them.
desculpa e que eu ñ prestei atenção mas se for 50% da iluminaçao
sou novato, tenho um carregador universal quebrado pretendo juntar ele com esse circuito para carregar baterias de 500, 900 e 1020ma cera que dar certo?
a iluminação dura quanto tempo?
qs (author)  douglas marcelo9 months ago
2 hours.
qs (author)  acmefixer4 years ago
It's made from a cut down 'AA' holder. The details were previously posted under 'My Blinkie Thingie' here