1. The positive and negative ends of the voltage source are connected with a capacitor (in parallel with the circuit), which has a good filtering effect in the rectifier circuit. When the voltage alternates, due to the charging action of the capacitor, the voltage at both ends will not suddenly change, ensuring the stability of the voltage.

When used for battery power supply, it has the role of an AC channel, which is equivalent to short-circuiting the AC signal of the battery, thus avoiding the parasitic oscillation of the circuit caused by the increase of the internal resistance of the battery caused by the reduction of the battery voltage.

2. For example, what kinds of circuits can be coupled with series or parallel capacitors? What is the difference between a non-discharge capacitor and a discharge capacitor?

In the AC multistage amplifier circuit, due to the difference in the gain and power of each stage, the DC bias value of each stage is also different! If the levels are coupled directly, all the levels will not work properly. By using the characteristics of capacitance, the coupling of inter-stage AC is solved and the inter-stage bias value is isolated, killing two birds with one stone!

3. The two coupling capacitors in the basic amplifier circuit, the capacitor pole and the DC pole are connected to each other, and play the role of communication and isolation. What happens if you reverse it? Will they also serve as communication and isolation? Why are they connected there?

Otherwise, the electrolytic capacitor will leak, change the DC operating point of the circuit, and make the amplifier circuit abnormal or unable to work.

4. What is the role of capacitance in the resistance-capacitance coupling amplifier circuit?

DC signals are isolated so that the static operating points of adjacent amplifying circuits are independent of each other and do not affect each other.

5. Can analog amplifiers be amplified without coupling capacitors? The amplifier adds a coupling capacitor between the transformer secondary coil and the triode. The explanation is that the AC resistance DC is switched on, and the output of the previous stage becomes the input of the next stage, so that the front and rear stages are not affected. The former stage is AC, the latter stage is AC, so how can the two affect each other? I can't figure it out. Adding a capacitor isn't unnecessary.

You made a mistake. The former stage is indeed AC, but the latter stage is AC plus DC. A triode requires DC bias. If there is no capacitor for DC isolation, the coil of the transformer will bias the DC of the bypass triode (because the inductor is DC connected).

6. The coupling capacitance of the basic amplifier circuit, where the coupling capacitance can be non-polar?

In a basic amplifier circuit, the coupling capacitance depends on the video rate. When the frequency is high, you need a non-polar capacitor, which is characterized by stability, high voltage resistance, relatively small volume, but small capacity. Its most important use is that it can cut off direct current through alternating current, which is widely used in high-frequency AC current path, bypass, resonance and other circuits. (Simply understood as high-frequency path)

When the frequency is low, because the capacitance of the non-polar capacitor is low, the capacitance reactance is relatively increased, so it is necessary to use a polar electrolytic capacitor. Because the electrolyte is added inside, the capacity can be made large, so that the low-frequency alternating current passes through and the direct current is cut off. However, because the middle of the inner pole is an organic medium, the voltage resistance is limited, and it is mostly used for low-frequency AC channels, filtering, decoupling, bypass and other circuits. (Simply understood as low-frequency path)7. Please tell the circuit master what the coupling capacitor does.

In an amplifier circuit, coupling capacitors are used to allow high-frequency AC signals to pass smoothly through the circuit and be amplified step by step, while the DC current is blocked at each stage.