By this token, the physics of semiconductors, which is required to explain how the crystal detector receiver works, is also uncommon knowledge among beginners!

By this token, the physics of semiconductors, which is required to explain how the crystal detector receiver works, is also uncommon knowledge among beginners! Both computers and semiconductors can be explained qualitatively, bringing in the ideas like a one-way valve, or following written instructions. This, of course, would gloss over a ton of things, much like the optimized crystal radio blissfully lacks the RF filter in the audio frequency circuit: the mechanical properties of the earphone suffice. "All models are wrong, but some are useful", as they say.