Most of the capacitor
values has been written on them especially on electrolytic capacitors, like
10μF that stands for 10 micro-Farads. For them, the value is straight-forward. There
are some smaller types of capacitors with a coded 2 or 3 digits number on them.
If there are 2 digits printed on them, then this is the exact value in
pico-farads. For example, 21 means 21 Pico-Farads. For the 3 digits code, the
first 2 digits are the significant digits (in pico-Farads) and the third is the
multiplier. The multiplier digit is as follows:
Multiplier
digit |
Multiplier
value |
0
|
1
|
1
|
10
|
2
|
100
|
3
|
1.000
|
4
|
10.000
|
5
|
100.000
|
6
|
|
7
|
|
8
|
0,01
|
9
|
0,1
|
A capacitor with code 322 means 32*100 pico-Farads = 3200 pF=3,2 nano-Farads.
Sometimes, a tolerance letter is also added at
the end of the code. These letter tolerances are as follows:
Tolerance
letter |
Tolerance
value |
D
|
+/- 0.5
|
F
|
+/- 1%
|
G
|
+/- 2%
|
H
|
+/- 3%
|
J
|
+/- 5%
|
K
|
+/- 10%
|
M
|
+/- 20%
|
P
|
+100% ,-0%
|
Z
|
+80%, -20%
|
So a 103J is a 10,000 pF
with +/-5% tolerance
Capacitance
is measured in “farads.” There are picofarads (pF),nanofarads
(nF), and microfarads (μF).
Color
coded capacitors always have 4 bands, and are measured in picofarads
– the smallest unit of measurement.
Equivalents:
1,000,000pF (picofarads) = 1,000nF (nanofarads) = 1μF (microfarad)
Capacitors color code
Things may get a little
more complicated in this section so make sure that reading a value from a
carbon resistor is clear for you.This color code is
mostly applied to ceramic capacitors, but could be also met to other types of capacitors
too. It is not very popular, but is good to know how it works. And here is how
it goes:
Same as a resistor, a
capacitor's color code is read in even way. Notice that on the left side as you
see the cap there mast be an thicker strip or the strip must be at the edge of
the capacitor. If you have a disc type capacitor then there is no problem of
course. The first strip is the temperature coefficient. You can ignore this
strip. The second and the third strip are the significant digits and the fourth
strip is the multiplier (result in pico Farads). Use the same methodology as
reading a resistor to get the value of the capacitor. For example:
Lets choose a capacitor having color coding as below:-
Second strip: Orange (3)
Third strip: Red (2)
Fourth strip (Multiplier): Orange (x 1.000)
This capacitor's value should be 32*1000=32.000 pF=32nF
Second strip: Orange (3)
Third strip: Red (2)
Fourth strip (Multiplier): Orange (x 1.000)
This capacitor's value should be 32*1000=32.000 pF=32nF
The tolerance is
different for capacitors less than 10pF and for capacitors more than 10pF. For
the previous example, the capacitor is more than 10pF. If the last strip was
green, the tolerance should be +/-0.5%.
Above given table for capacitors is self explanatory.
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