The
capacitors have specific values which are marked on to the body of the
capacitor, that helps to understand the capacitance and other properties
of it. The important values for the capacitor are the capacitance,
tolerance, voltage rating, temperature coefficient etc. These are
usually marked on the body of the
capacitor in the alphanumeric form. There are many decimal values that
are used as capacitor values where the reading becomes difficult without
the help of a capacitor value chart. To reduce the confusion involved
with the letters, numbers, and decimals
used in representing capacitor values and also to prevent misreading the
values of the capacitor, an international color coding scheme was
introduced. The capacitor color code represents a simple and efficient
way of reading capacitor values and tolerances.
Photo credit: live.partlist.org
There
are different build of non polarized capacitors such as the axial lead,
radial lead, and ceramic disc capacitors. The disc type of capacitor
color code is read from the top of the capacitor to the bottom of the
capacitor. The extreme end of the body of the capacitor is considered as
top of the capacitor and towards the axial leads is considered as the
bottom of the capacitor. The color marking at the top of the capacitor
is considered as the first color band. In radial and axial lead type of
capacitors the ring near any of the lead is considered as the first
color band.
Photo credit: smartdraw.com
The first band A
is usually the value for the temperature coefficient of the capacitor, which is
denoted as A. The second band B is the first digit of the capacitor in picofarads, denoted as B. The third band C is the second digit of the capacitor in picofarads,
denoted as C. The fourth band D is the multiplier of the capacitance in
multiples of 10, denoted as D. The fifth band E is the tolerance of
the capacitor in percentage, denoted as E.
More recently a different type of capacitor coding has come to be in use. In small types of capacitors such as film or disc form, instead of the color coding, the capacitance is given as a letter or a number code. The code consists of 2 or 3 numbers and an optional tolerance letter code to identify the tolerance.
When a 2 letter code is used, the value of the capacitor is denoted in picofarads such as 10 = 10pf, 22 = 22 pf, and 100 = 100 pf etc. The 3 letter code is used to denote the value of capacitor, the first two digits for the first and the second value of the capacitor and the third one is multiplier in picofarads which multiplies in multiples of 10. For example a capacitor with a value 251 = 25 * 10 = 250 pf and 102 = 10 * 100 = 1000 pF etc. There is an additional letter included in a 3 digit code to include the tolerance measurement of the capacitor. For example a capacitor with a value 103J printed on the body, which denotes the 1st and 2nd digits as the 1st and 2nd value of the capacitor and the 3rd one is denoted as the multiplier in picofarads and the letter J is the tolerance.
10 * 1000 = 10,000 pf and the letter J denotes a tolerance of +/- 5%
The capacitance is 10,000 pF which is equivalent to 10 nF or 0.010 mF with a tolerance of +/- 5%
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