3 upvotes, 2 direct replies (showing 2)
View submission: Ask Anything Wednesday - Engineering, Mathematics, Computer Science
Let’s say I had a long string of LEDs, say 1km, with the LEDs spaced a meter apart, open circuit at the end. Could I, in theory, send a voltage pulse down the wires that’s below the voltage threshold of the LEDs but then send another precisely timed pulse that will constructively interfere with the reflected first pulse to create pulse that is above the threshold voltage of the LEDs and turn on a single LED where the two pulses interact?
Edit: LEDs are wired in parallel.
Comment by mfb- at 26/06/2024 at 17:25 UTC
4 upvotes, 0 direct replies
Getting only a single LED to light up is probably unrealistic, but the general concept works.
Comment by LanceWindmil at 26/06/2024 at 16:00 UTC
-3 upvotes, 2 direct replies
So there are two problems here
First LEDs are diodes, so they only let current pass on way. You could still do something similar with a circuit in parallel though.
The bigger issue is that electricity moves really fast. Pretty close to light speed. So to create a "wave" would be nearly impossible. As soon as you increase the voltage on one end it would increase the voltage in the whole circuit near instantly.
Instead what you'd get is the entire kilometer of LEDs blinking at once when the frequencies line up.