Electrolytic capacitor, tantalum capacitor, ordinary capacitor

1、 Electrolytic capacitor ： The metal foil is the positive pole （ Aluminum or tantalum ）, The oxide film of the metal close to the positive electrode （ Alumina or tantalum pentoxide ） It's dielectric , The cathode is made of conductive material 、 electrolyte （ Electrolyte can be liquid or solid ） And other materials , The electrolyte is the main part of the cathode .

2、 Ordinary capacitors ： Isolated conductors form a capacitance with infinity , Conductor grounding is equivalent to connecting to infinity , And connected with the earth as a whole .

The full name of tantalum capacitor is tantalum electrolytic capacitor , It also belongs to a kind of electrolytic capacitor , Use tantalum as the medium , Unlike ordinary electrolytic capacitors, electrolyte is used , in addition , Tantalum capacitors do not need to be fired with aluminum coated capacitor paper like ordinary electrolytic capacitors , So it has almost no inductance , But it also limits its capacity .

Tantalum capacitors have a longer life than electrolytic capacitors , But at present, tantalum capacitors are not as large as electrolytic capacitors , The voltage is not as high as that of electrolytic capacitor .

There is electrolyte inside the aluminum electrolytic capacitor , It expands when heated , Overheating will explode （ If there is an explosion-proof valve, it will open the explosion-proof valve , Leakage ）, So the working temperature of electrolytic capacitor is generally the highest 105 degree , There is no liquid inside the tantalum capacitor , High temperature resistance , There is no danger of leakage .

Besides , There is no electrolyte inside the tantalum capacitor , Very suitable for working under high temperature
Tantalum capacitors are characterized by long service life 、 High temperature resistance 、 High accuracy 、 Excellent high frequency filter performance , But the capacity is small 、 The price is also more expensive than aluminum capacitors , And the ability to withstand voltage and current is relatively weak .

Electrolytic capacitors are the most common capacitors , Its capacity is relatively large , And it has polarity , It is generally used in low-frequency filtering and signal coupling 、 Input and output . The working frequency of electrolytic capacitor is very low , commonly 1KHZ following ,, Tantalum capacitors have better high frequency characteristics , The frequency range covers electrolytic capacitors .

Electrolytic capacitors can withstand high voltage , Common electrolytic capacitors （ As used in switching power supply ） Yes 400V The above , Tantalum capacitors are difficult to withstand high voltage , The general working voltage is 10V about , High has 16V Of , No matter how high it is, it's rare , Especially low capacity , The pressure resistance is lower , I've seen 470UF The highest is 35V Withstand pressure , It's customized by military enterprises .

Electrolytic capacitors are not suitable for use in places with large temperature changes . . The material and technology of electrolytic capacitor determine that it is easy to be affected by ambient temperature , The tantalum metal of tantalum capacitor is very strong and stable .

. When the ripple current of electrolytic capacitor exceeds the rated value, the greatest danger is heating 、 The explosion 、 Leakage , If the ripple current of tantalum capacitor exceeds the set value, it will explode 、 catch fire , And the tantalum capacitor resists overcurrent （ Ripple current ） Poor ability , Very easy to catch fire , This is the biggest weakness of tantalum capacitors .

The polarity of the electrolytic capacitor , Pay attention to the side of the electrolytic capacitor “-” Yes 、“+” It's positive , If the electrolytic capacitor is not marked with positive and negative electrodes , It can also be judged according to the length of its pin , The long foot is positive , The short leg is negative .

The role of electrolytic capacitors

1、 The first use is to put it in the circuit to block DC , It can be used as a DC switch , That is to say, the direct current is approximately regarded as an open circuit , The communication is approximately regarded as closed .

2、 The second use is in switching power supply circuit design , After the rectifier circuit comes out , To connect a large capacity electrolytic capacitor , It can make the pulsating DC voltage very stable , Harmful AC components are introduced into the earth .
( Electrolytic capacitors are only suitable for use in DC circuits , Therefore, the AC circuit will be broken down and short circuited , No matter how high the voltage is . If the diode is connected in series in front of the electrolytic capacitor , Maybe it can act as a rectifier , But it won't be long . After the polarity of electrolytic capacitor is reversed , Finally, it was punctured , It may even explode . )

3、 The third use is mutual coupling . Generally, it is connected between the two-stage circuits of low-frequency signal transmission and amplification , It can prevent two static working points from interfering with each other , Only AC signals are allowed to pass through .

4、 The fourth purpose is the function of bypass , Provide low impedance loops for some components in AC circuits .

5、 The fifth purpose is to store energy , Used to release the required current under certain conditions .

6、 The sixth purpose is to adjust the resonant frequency , Such as radio circuit ,LC Crystal oscillator circuit .

PCB Icons in design
Electrolytic capacitor

Ordinary capacitors

Tantalum capacitor picture

Source of the article
What is the difference between tantalum capacitors and electrolytic capacitors ？
The role of electrolytic capacitors
Tantalum capacitance , What is the difference between electrolytic capacitor and ordinary capacitor ?
What is the difference between electrolytic capacitor and ordinary capacitor ？