Today we are going to use math and science to build a rechargeable LED light. For the science part, you will need: Rechargeable Lithium Battery, 150 ohm resistor, and white LED light (from Christmas LED lightbulb). For the math part, you...
I salvaged SMD resistors from broken CFL nightlight to make LED flashlight. Since it has 150 ohm SMD resistor, I can solder together a small portable flashlight powered by rechargeable 250 mAh lithium battery.