This two-transistor circuit is from a December 1964 Radio Electronics. Modern transistors can be tested. The headphone must be high impedance or crystal with a 2k2 resistor in parallel.
This simple radio was found in a Popular Electronics from the 90s. L1 and L2 have 100 turns on a...
This circuit was found in Radio Electronics magazine from the 90's. The circuit is for small NiCad...
This automotive circuit was obtained from an 80's schematic from the integrated circuit factory...