This early electronic oscillator relies on magnetic coupling between an inductor in the input circuit and a secondary coil in the output circuit. The secondary coil feeds a portion of the amplified signal back into the input with the correct phase to sustain continuous oscillation. It was widely used in early radio receivers for regenerative amplification.
We built a simple Armstrong oscillator on the bench to demonstrate magnetic feedback to the students.
This topology is highly sensitive to the physical placement of the coils, making it a classic example of how parasitic coupling can either make or break an RF circuit.
Also heard as
- Meissner oscillator
Related terms
Tickler coil
A historic inductor coil used to feed a portion of an amplified signal back to the input.
Coil
A passive electrical component made of wire wound into a spiral or cylinder to create a magnetic field.
Inductor
A passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.