Hartley oscillator

Schematic Diagram

The Hartley oscillator is an LC electronic oscillator that derives its feedback from a tapped coil and is varied in frequency by a variable capacitor. A Hartley oscillator is therefore a type of inductively coupled variable frequency oscillator.

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

• Integrated Publishing's Hartley oscillator (http://www.tpub.com/content/neets/14181/css/14181_81.htm)