First quarter of the period. The positively charged capacitor plate connected to the collector is discharged. The current in the oscillating circuit rises to its maximum value. An induction current occurs in the coupling coil in such a direction that the base has a negative potential relative to the emitter. Transitions base – collector and emitter – base are straight. The transistor is open. The energy from the source goes through the transistor to the oscillatory circuit (the key is closed).
Second quarter of the period. The loop current decreases. The top plate is charged negatively. In the coupling coil, the current changes direction. Based on positive potential. The collector-base transition is reversed. There is no current in the circuit (the key is open).
Third quarter of the period. The capacitor is discharging. The current rises to its maximum value, directed from the bottom plate to the top. In the coupling coil, the current is directed so that the base receives a positive potential. Transition base – reverse collector. There is no current in the circuit (the key is open).
Fourth quarter of the period. The current in the loop decreases without changing direction. The top plate is charged positively.
In a coupling coil, the current changes in direction. The charge on the base is negative. Transitions base – collector and emitter – base are straight. Energy comes from the source to the oscillatory circuit (the key is closed).
Thus, continuous electromagnetic oscillations occur due to the flow of energy from the source into the oscillatory circuit for 1/2 T.
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