Ask the master to explain the divination of oscillation test!

1, master the influence of transistor (oscillator) working state, feedback size and load change on oscillation amplitude and waveform.

Influence.

2. Master the working principle of the improved capacitor three-point sine wave oscillator and the measurement method of oscillation performance.

3. Study the influence of external conditions on the stability of oscillation frequency.

4. Compare the frequency stability of LC oscillator and crystal oscillator, and deepen the frequency stability of crystal oscillator as follows.

He Gao's understanding.

Second, the experimental principle and circuit

Sine wave oscillator is a kind of oscillator whose oscillation waveform is close to ideal sine wave, which is widely used.

Class circuit, there are many forms of oscillating circuits that produce sinusoidal signals, but in summary, they are nothing more than RC, LC and crystal.

There are three types of oscillators. This experiment mainly studies LC three-terminal oscillator and crystal oscillator.

The basic circuit of LC three-terminal oscillator: according to the phase balance condition, the oscillator is formed.

Among the three reactances of the oscillating circuit, X 1 and X2 must be the same.

Natural reactance, X3 must be reactance of different properties, and

They should satisfy the following relations:

X3 = -(X 1+X2) (4- 1)

This is the phase balance condition of LC three-terminal oscillator.

Criteria for judgment.

If X 1 and X2 are capacitive reactance and X3 is inductive reactance, then

It is a capacitor three-terminal oscillation circuit; If X 1 and X2 are both

Inductance, X3 is capacitive reactance, and it is an inductive three-terminal oscillator.

(I can't send the picture, sorry)