How do LED keychain flashlights get away with no dropping resistor?
Currently available LEDs are more energy efficient than incandescent bulbs, but less than florescent bulbs with the same light output. The power consumption of popular LEDs ranges from 30mW to 200 mW.
People can save money & energy by using LEDs instead of equivalent incandescent decorative bulbs.
The rated average working life of LED is 100,000 hours compared with 1,000 hours of incandescent bulbs.
LEDs emit cold lights as working LEDs generate very small amount of heat, so LEDs are much safer than equivalent incandescent light bulbs in terms of danger of fire. LEDs don’t have filaments to heat up in order to emit lights just like the case of incandescent bulbs. Lights are emitted from LEDs as a result of energy exchange occurring in the different semiconductor materials an LED is made of.
LEDs are usually shielded with solid transparent plastic materials so they are more rugged than incandescent and florescent bulbs that are usually sealed with glass.
LEDs can be powered by either AC voltage or DC voltage. The circuit that is required to appropriately drive LEDs is much simpler than that for florescent bulbs