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Hartley oscillator


Schematic Diagram

The Hartley Oscillator is an LC oscillator that derives its feedback from magnetically coupled energy in a tapped coil. Hartley oscillator are inductively coupled variable frequency oscillators.

Hartley oscillators may be series or shunt fed.

Structure:

One centre tapped inductor.
One tuning capacitor.

Advantages:
Frequency simply varied by capacity net value in the tank circuit.
Output amplitude remains constant (over the frequency range).
Feedback ratio of inductor 1 to inductor 2 remains constant.

Disadvantages:
Harmonic content rich.
Not suitable for a pure sine wave.

See also: Colpitts oscillator | Clapp oscillator | Vackar oscillator | Armstrong oscillator

External links, references, resources