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Basic info of capacitors

Capacitor is kind of electronic components that can very quickly store and release electric charges. A capacitor basically consists of two mutually insulated conductive plates. Capacitors are needed in virtually all electronic circuits.


A capacitor is measured by the size of its capacitance. A capacitance is the electric capacity of a capacitor.

How to read Semec capacitance code?

The first two are the 1st and 2nd significant digits and the third is a multiplier code.

The last digit tells you how many zeros to write after the first two digits.

Rated Voltage

Each capacitor is designed for a particular rated voltage, which it must stand up to without adverse effect during continuous operation. Also, there are DC and AC and DCC voltage specifications are distinguished from AC.

In Semec capacitors line card, SCA metallized Polyester film capacitor, X2 Metallized Polypropylene Film capacitor and Y1/Y2 Semec Safety standard capacitor are AC Voltage. Other Film capacitor, Ceramic Capacitor, Tantalum Capacitor are DC voltage.

Capacitance Tolerance

Tolerance is the permissible relative deviation of the capacitance from the rated value, expressed in percent.

Below is general capacitance tolerance of SEMEC capacitors:


And special capacitance tolerance will occur upon to change with special request, such as ±1% or others possible.

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