Linear Modulated LED the led current follows the input signal but inverted the current goes from 4mA to 12mA the input gain is around 4
Not tried this but you could input a audio signal and the LED would fade in sink with the audio
Or you could send the led output down a fiber optic cable and use a photo transistor to demodulate the signal some distance away
Will experiment with this circuit and post
Modified version by hurz thank you
Further simplified by hurz
