Such a device is commonly called a crystal radio[1] and they truly are ridiculously simple. If you don’t need a tuner or an amplifier, which in this case was li

Such a device is commonly called a crystal radio[1] and they truly are ridiculously simple. If you don’t need a tuner or an amplifier, which in this case was likely, the only components required to build an AM receiver are an antenna, a diode, and an earphone. The name derives from an early type of diode based on a piece of crystalline mineral, discovered by Braun in 1874[2]. [1] https://en.wikipedia.org/wiki/Crystal_radio https://en.wikipedia.org/wiki/Crystal_radio [2] https://en.wikipedia.org/wiki/Crystal_detector https://en.wikipedia.org/wiki/Crystal_detector