The capacitance of a capacitor is usually printed on them either in codes or directly, it is use to identify different capacitance values of different capacitors that are required in different circuits.It is very important to understand how to calculate capacitors codes, it's very simple to understand but those who find it difficult to read use capacitance meter to determine it.
There are many types of capacitors, here is how to calculate their capacitance values. The capacitance of capacitors like ceramic and mica capacitors are calculated in pico farad (P).
There are many types of capacitors, here is how to calculate their capacitance values. The capacitance of capacitors like ceramic and mica capacitors are calculated in pico farad (P).
1.Electrolytic capacitor.
Everyone is familiar with electrolytic capacitors, they have polarity with one marked side negative and other side's terminal of positive polarity, an example is shown above. Their capacitance value is usually printed on them in micro farads, like the one above which is 470uF, u is a short form of micro = 0.000001, also 470uF means 470×0.000001F.
Moreover, their maximum working voltage is printed on them. e.g 25v as shown above.
2. Ceramic capacitor.
EIA tolerance capacitance markings.
Letters Tolerance values.
J...................................................+/-5%
F....................................................+/-1%
K.................................................+/-10%
M.............................................+/- 20%
D................................................+/-0.5%
C.............................................+/-0.25%
B...............................................+/-0.1%
EIA working voltage codes and values.
Some capacitors which are small to print on, do have their working written in codes. The codes and their values are listed below.
Codes. Working voltage
OG.............................................4.0VDC IJ................................................63VDC 2D.............................................200VDC Ol...............................................5.5VDC Ok...............................................80VDC 2P............................................2020VC OJ..............................................6.3VDC 2A............................................100VDC 2E.............................................250VDC A.................................................10VDC 2Q............................................110VDC 2F.............................................315VDC IC................................................16VDC 2B.............................................125VDC 2V.............................................350VDC 1E...............................................25VDC 2C............................................160VDC 2G............................................400VDC 1H..............................................50VDC 2Z.............................................180VDC 2W............................................240VDC
Let's calculate the capacitance value of the capacitor shown above.
Calculations.
The first two numbers are significant i.e 10, the third which is 4 is the multiplier i.e 10× 10^4 = 10×10,000= 100,000pF. Converting to shorter form it will be 100,000×1/1000000000000 = 0.1uF✅ 3. Mica capacitors.
The value calculation of mica capacitors are very similar to ceramic types. Here the first two numbers are significant,the third number is the multiplier and the last letter is the tolerance value with the same values as ceramic capacitors code listed in the table above, while the last alphanumerics which is 400v is the working voltage. For better understanding let's calculate capacitor's value below.
Calculations.
The first two figures i.e 22 are significant, the third number is the multiplier, i.e 22×20^3=22000.
The fourth which is a letter J is the tolerance i.e 5% whole the next figures 2kV (2000v) is the maximum working voltage.
Thus the capacitance of the capacitor is 22000pf.
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Basic Electronics