Can I use Resistor to minimize the voltage of LED? Can this plan function to Crystal Radio?

Question

This is important

Answer 1

I think you mean to use a resistor to reduce the voltage drop in a forward-biased LED, which is about 2.5v. The answer is no. You should use a germanium diode with voltage drop of .4 volts for your project. Germanium diodes are much cheaper than LEDs. Why do you want to use an LED as the detector in a crystal radio? Unless you have a great deal of amplification of the RF signal, you will never get enough voltage from your antenna to use an LED as a detector.

Answer 2

You most certainly can use a resisitor to induce a voltage drop to a LED. You can also use a AA, AAA to power it directly without fear of burning it out. Just be sure that you use a resistor that has enough wattage to handle the drop without getting hot.

Crystal Radios do not use power to function. They convert the electromagnetic RF in the air directly to electrical current via the crystal.