If a capacitor is f.ex. marked 2A474J, the capacitance is decoded as described above, the two first signs is the voltage rating and can be decoded from table 2 here below. 2A is 100VDC rating according to the EIA standard. Some capacitors are only marked 0.1 or 0.01, mostly in these cases the values are given in uF.
These capacitor codes are standardised by EIA, but also some other generally used industry codes may also be seen in common use. These codes are typically used for ceramic and other film type capacitors. The temperature coefficient is quoted in terms of parts per million per degree C; PPM/°C.
A: In a three-digit capacitor code, the first two digits represent the significant figures, and the third digit represents the multiplier. To determine the capacitance, combine the first two digits and multiply them by 10 raised to the power of the third digit. For example, a code of “104” translates to 10 x 10^4 pF = 10,000 pF or 10 nF.
Colour code: Some older capacitors use a form of colour code. This type of capacitor marking is used less these days but may be seen on some older capacitors. Tolerance codes: Some capacitors have a tolerance code. The code used is actually the same as that used with resistors as it utilises the EIA scheme:
Many larger capacitors like electrolytic capacitors, disc ceramics, and many film capacitors are large enough to have their markings printed on the case. On a larger capacitors there is sufficient space to mark the value, the tolerance, working voltage, and often other data such as the ripple voltage.
Chart1: CAPACITOR MARKING CODE STANDARDIZED BY THE ELECTRONIC INDUSTRY ALLIANCE (EIA) The voltage rating on a capacitor indicates the maximum voltage it can safely handle. This parameter is ensuring safety and performance, as it prevents over-voltage failures that can damage both the capacitor and the surrounding circuitry.