LC oscillator circuit works
The electrical disturbance generated at the instant of power-on is amplified by an amplifier composed of a triode V, and then the resonant frequency F0 is selected from a plurality of frequencies by the LC frequency selective loop. The signal is fed back to the base of the triode through mutual inductance coupling between coils L1 and L2. Let the base voltage polarity be positive. The instantaneous polarity of the inverted set voltage is negative. According to the sign of the same name of the transformer, it can be seen that the polarity of the upper end of L2 is negative, and the polarity of the voltage fed back to the base is positive, satisfying the phase balance condition and deviating from other frequencies of F0. The signal does not satisfy the phase balance condition because of the additional phase shift. As long as the triode current amplification factor B and the ratio of the turns of L1 and L2 are appropriate, and the amplitude condition is satisfied, the oscillation signal of the frequency F0 can be generated.
LC oscillation circuit
Provide a stable clock signal to the microcontroller. Principle: Applying an electric field to the two plates of a quartz crystal, the wafer will be mechanically deformed, applying mechanical force to the plate to deform it, and generating a corresponding charge on the plate. This is called the piezoelectric effect. If a voltage is applied to the two plates, the wafer will be mechanically deformed, and this mechanical oscillation will also produce an alternating electric field (smaller comparison), but when the frequency of the applied alternating voltage is inherent to the wafer When the frequencies (determined by their shape and size) are equal, the amplitude of the mechanical vibration is increased, and the alternating electric field is also increased. It is called piezoelectric harmonics. Even if the crystal oscillator is removed, the circuit can still oscillate, and if you change the two capacitors into a tunable capacitor, you can get the desired frequency, and what else does the crystal oscillator do: crystal oscillator, ceramic resonant tank, RC oscillator, and Silicon oscillator is suitable
