You don't need PN junctions for an AM radio. Accidental point-contact diodes might be enough nonlinearity (for mixing) and rectification. Here's a fun jumping

You don't need PN junctions for an AM radio. Accidental point-contact diodes might be enough nonlinearity (for mixing) and rectification. Here's a fun jumping off point for a deeper dive: http://www.sparkbangbuzz.com/ http://www.sparkbangbuzz.com/