What is the formula for Hartley Oscillator Frequency?

The Hartley Oscillator Frequency formula is f = 1 / (2π√((L1 + L2) × C)), where f—Oscillation frequency (Hz); L1, L2—The two inductor sections (H); C—Tank capacitor (F).

What does f mean in the Hartley Oscillator Frequency formula?

f is Oscillation frequency (Hz).

Hartley Oscillator Frequency

Q: How do you calculate Hartley Oscillator Frequency?

Use the formula f = 1 / (2π√((L1 + L2) × C)). The Hartley oscillator is the inductive dual of the Colpitts: its tank uses a tapped inductor (or two inductors in series) with the tap providing feedback, resonating with a single capacitor. Enter the values you know in the calculator above and it solves for the remaining variable.

f = 1 / (2π√((L1+L2) · C))

Calculator

Frequency

Inductor L1

Inductor L2

Tank Capacitor

Result

—

Formula

f = 1 / (2π√((L1 + L2) × C))

Description

The Hartley oscillator is the inductive dual of the Colpitts: its tank uses a tapped inductor (or two inductors in series) with the tap providing feedback, resonating with a single capacitor. The total tank inductance is the sum of the two sections plus any mutual coupling. Hartley circuits are easy to tune with a variable capacitor and were widely used in radio receivers.

Variables

f — Oscillation frequency (Hz)
L1, L2 — The two inductor sections (H)
C — Tank capacitor (F)

Practical Notes

If the two coil sections are magnetically coupled, add 2M to the total inductance. The L1/L2 ratio sets the feedback fraction needed to sustain oscillation.

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