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.
This circuit acts on the dynamic range of an audio signal, which can be useful for recording,...
This is the conventional application of the UCN4202 to control a 12 V stepper motor with current...
Described in the December 1969 Radio Electronics magazine, this circuit is intended to supply the...