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2026. 6. 30. 작업

증상

How does a lightbulb with two filaments know which one to light up?

처리 내용

A typical 1157 taillight bulb looks like this: The filaments have a common connected to the shell and the other end of each goes to each the two terminals on the bottom of the bulb. The bayonet pins are offset so the bulb can only be inserted one way. In the case of the 1157 bulb, the elements are 26.8W/8.3W, and have about a 10:1 difference in lumens (and about 1/4 the lifetime for the brighter brake light filament).