Transformer Oscillator

Transformer oscillator is also called Armstrong oscillator. This oscillator uses a transformer coupling to feed back part of the output signal
voltage, as shown in the figure. Because the transformer secondary coil is also a "feedback coil", this oscillator has This is sometimes called a "feedback"
oscillator, where the transformer secondary coil provides feedback to allow the oscillation to continue. The Armstrong oscillator is not as commonly used as the Colpitts
, Clapp, and Hartley oscillators , mainly due to shortcomings such as the large size and high cost of the transformer . The oscillation frequency is determined by the parallel connection of the inductance (Ll) and Cl of
the primary coil .