In the previous post, we discussed about Ceramic capacitors. Now, we will discuss about the Electrolytic capacitor. Electrolytic capacitor is named so because the dielectric which is used in it is an electro chemically treated oxide form. Electrolytic capacitor comes under the category of polarized capacitors. As discussed earlier, the term ‘polarized’ means that these capacitors have a positive and negative end, and they should be connected that way only. A wrong connection may lead to abnormality / malfunction / defect in Electrolytic Capacitors due to the breakage of the very thin dielectric layer.

Electrolytic capacitor various sizesThe various properties of Electrolytic capacitor are as follows:

  • Dielectric Constant (K) – Like wise to the case of Ceramic capacitor, The Electrolytic capacitor also has high dielectric constant (K). Due to this, it offers high capacitance values still in reduced sizes.
  • Temperature limitation – As this type of capacitor contains an electrolyte jelly in it, it cannot be used below  -40ºC (as the low temperature may lead to the freezing of this jelly) and above +105ºC (as the high temperature may lead to the evaporation of this jelly). Earlier, I had mentioned -10ºC to +85ºC temperature range. However, I have changed it when my friend Harry updated me about the current development in temperature rating of Electrolytic capacitors.
  • Polarization – As mentioned above, Electrolytic capacitors are polarized.
  • Cost – They have a very low manufacturing cost.
  • Size – They are available in various sizes, from a huge one to a smaller one according to the requirement. It is why, like ceramic capacitors, the installation space is not an issue.
  • Reliability – They are quite reliable and one of the most used capacitors in the capacitor family. They also possess high tolerance value.
  • Capacitance range – They are normally available in large capacitance values ranging normally from 01 µF to few farads.
  • Voltage rating – They have a very low voltage rating. This is in fact one of the drawback of Electrolytic capacitors.

They are often used for circuits involving small frequencies like coupling / decoupling functions, power supply etc.

How to check the capacitance value and polarity of Electrolytic capacitors?

Answer

Capacitance Value: The capacitance value (as well as working voltage) is clearly written on Electrolytic capacitor. There is no decoding involved in this.

Polarity: The negative end is indicated with a minus (-) symbol. The other end which is unmarked will be Positive end.

In case, the negative end is not marked with a minus (-) symbol, then you can also identify it by a thin odd colour band above it.

In case if both is not available, then you can still identify it by seeing length of both the leads of Electrolytic capacitors. The length of negative lead is always kept smaller than the positive end at the time of manufacture for its identification.

Electrolytic capacitor2