This traditional signal injector configuration was obtained in a 1977 amateur radio manual. The frequency is given by the capacitors and the supply can be made with 1.5 or 3 V.
This circuit with transistors from a 1995 publication. The circuit is powered by a voltage taken...
Found in a 90’s American publication, this circuit has a voltage gain close to 1, as shown in the...
In the figure we show how to use a small Hartley oscillator as a continuity tester. The component...