Picture of Usb lamp with dark sensor
this is a cheap and easy way to use the usb power for the purpose of getting light. it consists of led, a transistor and some resistors. this can be used as a light source for the webcams at night, it can also be used  as a table lamp . if you like the circuit please rate it .    
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Step 1: Parts list

12 x   bright white leds 1200 
1    x  2N3904
1    x 100 r resistor
1    x  10k resistor
1    x  usb cable 
1    x 10 r 1/2 watt resistor
1    x LDR

Step 2: Circuit diagram

complete the circuit according to the circuit diagram, connect the led in parallel (you can add more led if you need) also check fr the polarity of the led before placing it on the board because re-soldering makes the circuit messy

Step 3: Step 2

Picture of step 2

Step 4: Conclusion

 hope you like the circuit......