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  • Discuss the role of electrolytic capacitor in the circuit design

    Talk about electrolytic capacitor we shall know more about it

    1, filtering effect: in the power circuit, rectifier circuit communication into pulsating dc, and after rectifying circuit connected to a larger capacity of the electrolytic capacitor, using the charge and discharge characteristics (storage), make rectification after the pulsating dc voltage is relatively stable dc voltage.In practice, in order to prevent the PCB manufacturing circuit of each part of the power supply voltage changes due to load changes, so in the output of the power and the power input end of the load average dozens to hundreds of micro method of electrolytic capacitor.Due to the large capacity of general has certain inductance electrolytic capacitor, the high frequency and pulse interference signal cannot be effectively filter, so the parallel connection at both ends with a capacity of 0.001-0. LpF of capacitance, to filter out high frequency and pulse interference.

    2,coupling effect: in the low frequency signal transmission and amplification process, in order to prevent the two levels of static working point of the circuit before and after the mutual influence, often using capacitive coupling.Rhyme in the low frequency component is to prevent the loss is too big, generally adopt large capacity electrolytic capacitor.

    To know more about the judgment method of electrolytic capacitors

    Electrolytic capacitor common fault, reducing capacity, capacity disappear, breakdown electric leakage, short circuit and the capacity change is due to the electrolytic capacitor is in use or place in the process of its internal electrolyte caused drying up, and the breakdown and voltage too high or leakage is usually caused by poor quality in itself.Judge of PCB proofing power capacitor commonly used to measure the resistance of multimeter.The specific method is: will be two pin short circuit capacitor discharge, use multimeter black pens and answer the electrolytic capacitor anode.Red pens and connect the cathode (was measured with a digital multimeter to the pointer multimeter, pens and intermodulation), whose hands should be small to the resistance of normal direction, then gradually return to infinity.The greater the oscillation amplitude of the clock or return the slower, the greater the capacity of capacitance, shows that the smaller the capacity of capacitance conversely.Whose hands refers to somewhere in the middle is no longer changes, such as that the capacitor leakage, such as the resistance is small or zero, indicating value indicates the capacitance is breakdown short circuit.For multimeter use battery voltage generally very low, so the measurement is more accurate at low voltage capacitance, and when the condenser pressure is high, while measuring normal play, but when combined with high pressure is the possible leakage or breakdown phenomenon.

    More attention need to understand the use of electrolytic capacitors

    1, electrolytic capacitor with positive and negative polarity, so can't reverse connection when used in the circuit.In the power circuit, the output of positive voltage electrolytic capacitor anode to connect power output, negative ground.When output load voltage output is negative, the anode grounding.

    When the power supply circuit of the filter capacitor polarity meet when, because of capacitance filtering effect is reduced greatly.Power supply output voltage fluctuations caused on one hand, on the other hand, due to the reverse current is equivalent to a resistor electrolytic capacitor fever at this time.When the reverse voltage exceeds a certain value, the capacitance of the reverse leakage resistance will become very small, so electricity work soon, can make a capacitance due to overheat and burst damage.

    2, on opposite sides of the electrolytic capacitor voltage should not exceed the allowed working voltage, in the design of the actual circuit should have certain allowance, according to the concrete situation in design of stabilized voltage supply filter capacitance, if the ac power voltage is 220 ~ transformer secondary rectifier voltage can be up to 22 v, PCB proofing as selection pressure for 25 v electrolytic capacitor generally can meet the requirements.But, if the ac power voltage fluctuation is very big and could rise to more than 250 v, had better choose pressure above 30 v electrolytic capacitor.

    3, electrolytic capacitor in the circuit should not be close to the high power heating element, in case the electrolyte accelerated because of the heat to dry up.

    4, with positive and negative polarity of the signal filtering, can take two series capacitors with polarity method, as a non-polar capacitor.

    5, capacitor shell, auxiliary leading-out terminal and the positive and negative as well as the circuit board must be completely isolated.

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