Recognize the role of capacitors in circuits from their names

Capacitors are almost indispensable energy storage elements in electronic circuits. They have the characteristics of blocking direct current, connecting alternating current and preventing low frequency. Widely used in coupling, DC blocking, bypass, filtering, tuning, energy conversion and automatic control circuits. Familiar with the names and meanings of capacitors in different circuits will help us to understand electronic circuit diagrams.

1. Filter capacitor It is connected between the positive and negative poles of the DC power supply to filter out the unwanted AC components in the DC power supply and smooth the DC power. Generally, large-capacity electrolytic capacitors are often used, and other types of small-capacity capacitors can also be connected in parallel in the circuit to filter out high-frequency alternating current.

2. The decoupling capacitor is connected in parallel between the positive and negative poles of the power supply of the amplifier circuit to prevent parasitic oscillation caused by the positive feedback formed by the internal resistance of the power supply.

3. Bypass capacitor In the circuit of AC and DC signals, the capacitor is connected in parallel at both ends of the resistor or is connected to the common potential from a certain point of the circuit, and a path is set for the AC signal or pulse signal to prevent the AC signal component from passing through the resistor. Produces pressure drop attenuation.

4. In the AC signal processing circuit, the coupling capacitor is used to connect the signal source and the signal processing circuit or as an inter-stage connection between the two amplifiers to cut off the DC, let the AC signal or the pulse signal pass through, and make the DC operating points of the front and rear amplifier circuits communicate with each other. Does not affect.

5. The tuning capacitor is connected to both ends of the oscillating coil of the resonant circuit and plays the role of selecting the oscillating frequency.

6. Pad capacitor is an auxiliary capacitor in series with the main capacitor of the resonant circuit. Adjusting it can make the frequency range of the oscillating signal smaller, and can significantly increase the oscillating frequency at the low frequency end. Appropriate selection of the capacitance of the pad capacitor can boost the low-end frequency curve upwards, approaching the ideal frequency tracking curve.

7. Compensation capacitor It is an auxiliary capacitor connected in parallel with the main capacitor of the resonant circuit. Adjusting this capacitor can expand the frequency range of the oscillating signal.

8. The neutralizing capacitor is connected in parallel between the base and the emitter of the triode amplifier to form a negative feedback network to suppress the self-oscillation caused by the inter-electrode capacitance of the triode.

9. Frequency stabilization capacitor In the oscillation circuit, it plays the role of stabilizing the oscillation frequency.

10. The timing capacitor is connected in series with the resistor R in the RC time constant circuit to jointly determine the length of the charge and discharge time.

11. The acceleration capacitor is connected to the oscillator feedback circuit to accelerate the positive feedback process and increase the amplitude of the oscillating signal.

12. Shortening the capacitor In the UHF tuner circuit, the capacitor connected in series in order to shorten the length of the oscillating inductor.

13. Clapper capacitor In the capacitor three-point oscillation circuit, the capacitor connected in series with the inductive oscillation coil plays the role of eliminating the influence of the transistor junction capacitance on the frequency stability.

14. Sila capacitor In the capacitor three-point oscillation circuit, the capacitor connected in parallel with the two ends of the inductive oscillation coil can eliminate the influence of the transistor junction capacitance, so that the oscillator is easy to vibrate at the high frequency end.

15. Amplitude stabilization capacitor In the frequency discriminator, it is used to stabilize the amplitude of the output signal.

16. Pre-emphasis capacitor In order to avoid the attenuation and loss of the frequency division amount caused by the audio modulation signal in the processing process, the set RC high-frequency component enhances the network capacitor.

17. De-emphasis capacitor In order to restore the original sound signal, it is required to attenuate the high-frequency components in the audio signal enhanced by pre-emphasis together with the noise, and set the capacitor in the RC network.

18. Phase Shift Capacitor Capacitors used to change the phase of an AC signal.

19. Feedback Capacitor A capacitor connected across the input and output of the amplifier to return the output signal to the input.

20. The step-down current-limiting capacitor is connected in series in the AC circuit, and uses the capacitive reactance characteristics of the capacitor to the AC to limit the AC current, thereby forming a voltage divider circuit.

twenty one. The flyback capacitor is used in the line scan output circuit, and is connected between the collector and the emitter of the line output tube to generate a high voltage line scan sawtooth wave reverse travel pulse, and its withstand voltage is generally above 1500V.

twenty two. The correction capacitor is connected in series in the deflection yoke loop to correct the extended linear distortion at the edge of the picture tube.

twenty three. The bootstrap boost capacitor utilizes the charging and discharging energy storage characteristics of the capacitor to increase the potential of a certain point of the circuit, so that the potential of this point reaches 2 times the voltage value of the power supply terminal.

twenty four. Capacitor for eliminating bright spots Set in the video amplifier circuit, it is used to eliminate the residual bright spots on the picture tube when it is turned off.

25. The soft-start capacitor is generally connected to the base of the switch tube of the switching power supply to prevent excessive surge current or excessive peak voltage from being applied to the base of the switch tube when the power supply is turned on, resulting in damage to the switch tube.

26. The starting capacitor is connected in series with the secondary winding of the single-phase motor to provide the starting phase-shifted AC voltage for the motor. Disconnect from the secondary winding after the motor runs normally.

27． The running capacitor is connected in series with the secondary winding of the single-phase motor to provide phase-shifted alternating current for the secondary winding of the motor. When the motor is running normally, it is kept in series with the auxiliary winding.