This circuit was found in documentation from the 1980s. The integrated circuit is from the time and the voltage depends on the desired power, and the component's datasheet should be consulted.
This simple receiver was found in a book on transistors from 1954. The coil determines the...
This configuration, quite common and found in other sites, is from European documentation from the...
The figure shows a simple way to obtain a negative voltage from a common source configuration. The circuit is...