How do I keep my LEDs from burning out in a magnetic induction coil?
Solution for the receiver: You can use a Zener diode for „eating up“ too much power. 

Place a small resistor in series with your LED. This will increase the voltage linearly with the LED current. Once this voltage reaches the break through voltage of the zener, any additional power will be absorbed by the diode and the LED current stays at its maximum. 

This circuit will also have the advantage of protecting your LED from too much reverse voltage during negative half wave. Of course, your zener must be able to handle that power. 







simulate this circuit &ndash; Schematic created using CircuitLab