If you are building an AM crystal radio. [1] You will also need a high-impedance speaker [2] if you want to operate it without a power supply, otherwise you wil

If you are building an AM crystal radio. [1] You will also need a high-impedance speaker [2] if you want to operate it without a power supply, otherwise you will need an amplifier. You can avoid using a commercial diode by making your own point contact diode as done in Foxhole radios [3] and you can make your own piezoelectric speaker from Rochelle salt [4]. Here [5] is one personal projects site touching all those topics. In conclusion, you should be able to build a simple radio from copper wire, aluminium foil, a pencil, a razor blade, and baking powder. [1] https://en.wikipedia.org/wiki/Crystal_radio https://en.wikipedia.org/wiki/Crystal_radio [2] https://en.wikipedia.org/wiki/Crystal_earpiece https://en.wikipedia.org/wiki/Crystal_earpiece [3] https://en.wikipedia.org/wiki/Foxhole_radio https://en.wikipedia.org/wiki/Foxhole_radio [4] https://en.wikipedia.org/wiki/Potassium_sodium_tartrate https://en.wikipedia.org/wiki/Potassium_sodium_tartrate [5] https://rimstar.org/science_electronics_projects/index.htm#SCIENCE_PROJECTS https://rimstar.org/science_electronics_projects/index.htm#S...