Test: Hartley Oscillator - Electronics and Communication Engineering (ECE) MCQ

Recommended frequency range of Hartley oscillator is 30KHz-30MHz. Frequencies higher or lower than this range will cause distortion.

Lower frequencies are theoretically possible in Hartley oscillator however in practice, the achievement of required inductive value is a problem.

The feedback used in Hartley oscillator is Voltage series feedback.

Center tapped inductors are used in Hartley oscillator to ensure feedback.

Inductive voltage divider bias is used in Hartley oscillator.

 There is only one capacitor is used in the tank circuit of Hartley oscillator.

There are two inductors in tank circuit of Hartley oscillator.

Frequency of Hartley oscillator can be expressed as 1/(2ᴨ√LC).

Active element used in Hartley oscillator is Transistor for amplification purposes.

As normal oscillators Hartley oscillator also uses positive feedback for sustained oscillation.

Inductance L1 and L2 are series and hence effective capacitance without mutual inductance will be L1+L2.

Common emitter transistor configuration is used in Hartley oscillator to ensure good oscillation.

Phase shift provided by tank circuit is 180 degrees to obey Barkhausen’s criteria for sustained oscillation.

The gain device in Hartley oscillator act as a band pass filter.

The phase difference provided by active element that is transistor is 180 degrees.

 Hartley oscillator make use of class C amplifiers because it can amplify signals less than 180 degrees and provide output of full cycle.

The Hartley oscillator is less preferred than due to Colpitts oscillator’s performance in high frequency regions due to stability.

 LC oscillators are also called self-limiting oscillators.

L1= 1mH
L2 = 2mH
Effective inductance L = L1+L2 = 1+2 = 3mH
C = 10μF
Oscillator frequency