Trinity Amps Trinity Tweed Amp, Builder'S Manual

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Version 3.2 Page: 69
How to read Capacitor Codes
Large capacitor have the value printed plainly on them, such as 10.uF (Ten Micro Farads) but smaller
disk types along with plastic film types often have just 2 or three numbers on them?
First, most will have three numbers, but sometimes there are just two numbers. These are read as Pico-
Farads. An example: 47 printed on a small disk can be assumed to be 47 Pico-Farads (or 47 puFf as
some like to say)
Now, what about the three numbers? It is somewhat similar to the
resistor code
. The first two are the 1 st
and 2
nd
significant digits and the third is a multiplier code. Most of the time the last digit tells you how
many zeros to write after the first two digits, but the standard (EIA standard RS-198) has a couple of
curves that you probably will never see. But just to be complete here it is in a table.
milli, micro, nano, pico
1 mili Farad (or any other unit) is 1/1,000th or .001 times the unit. (10
-3
)
1 micro = 1/1,000,000 or 0.000 001 times the unit (10
-6
)
1 nano = 1/1,000,000,000 or 0.000 000 001 times the unit (10 -9 )
1 pico = 1/1,000,000,000,000 or 0.000 000 000 001 times the unit (10 -12 )
Table 1 Digit multipliers
Third digit
Multiplier (this times the first two digits gives
you the value in Pico-Farads)
0 1
1 10
2 100
3 1,000
4 10,000
5 100,000
6 not used
7 not used
8 .01
9 .1
Now for an example: A capacitor marked 104 is 10 with 4 more zeros or 100,000pF which is otherwise
referred to as a 0.1 µF capacitor.
Most kit builders don't need to go further but there is sometimes a tolerance code given by a single
letter.
So a 103J is a 10,000 pF with +/-5% tolerance
Typical Capacitor Markings