Could I power an LED light off a headphone jack?

Okay, the reason why I'm asking is long, but, with some electrical know-how, could I power an LED light off a headphone jack? It's a weird question, I know, but it's a serious one. To my knowledge, they're both DC power, and the voltage should be similar, so i think they should work, but I might need to throw in... show more Okay, the reason why I'm asking is long, but, with some electrical know-how, could I power an LED light off a headphone jack?
It's a weird question, I know, but it's a serious one.
To my knowledge, they're both DC power, and the voltage should be similar, so i think they should work, but I might need to throw in a resistor. I'm not sure.

If it were possible, could i turn Morse, or maybe binary code into a visual signal? (that's the end result I'm looking for.)

Thanks a lot for any help with this!
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