How to determine the resistor for LED light with Rechargeable Lithium Battery

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Description: 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...

Electronic Salvage SMD resistor from CFL to LED Flashlight powered by rechargeable lithium battery

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Description: 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.