This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made of germanium of the time and the earphone is magnetic with high impedance.
This circuit is from National Semiconductor using an LM11, which is uncommon nowadays. The circuit...
Although it uses a dual-channel FET, which is hard to find today, this circuit was released in a...
We found this circuit in the April 1979 Radio Electronics magazine. Note the filter capacitor bank...