This crystal or galena radio was found in documentation from the 1990s. The earpiece must be a high impedance crystal or magnetic earpiece and D1 can be any germanium diode.
Found in National Semiconductor documentation from the 90's, this circuit has an output current of...
With this circuit it is possible to raise the characteristics of a transistor by checking its gain...
The circuit presented is from the Linear Applications Handbook of the National Semiconductor of...