Resistors & Capacitors

Recognising resistors and capacitors.

Resistor Value Table

Resistor Colour Coding
In most common resistors:
A = 1st figure of the value
B = 2nd figures of the value
C = Number of noughts to add (to make value in Ohms)
D = Tolerance
Gold: 5%, Silver: 10%, none: 20%

Yellow/Violet/Orange = 4700
47000 = 47K

(K is 000, M is 000,000)
Brown/Black/Orange/Gold
Is 10K (5%) etc
.

 

 

The European designation is becoming common these days in which the multiplier (K or M) replaces the decimal point. i.e.

4700 ohms=4.7K ohms - written as 4K7

1M ohm as 1M0

51 ohms as 51R etc.

 

Capacitor Markings and Values (µ and n etc.)

µ = microfarads, n = nanofarads, p = picafarads. The relationship is easy - the common ones are:

0.001uF = 1n9(=1000pF)

 0.01uF = 10n

0.1uF = 100n

There are a variety of (sometimes obscure) capacitor colour codings but the commonest markings on modern capacitors are:

 

Decade Markings:

A three number system where the third number is the number of noughts after the first two - which are the base value.

101 = 100pF

102 = 0.001uF (1n)

103 = 0.01uF (10n)

104 = 0.1uF (100n)

- are the common ones but watch out for confusion:

203 = 0.02uF

 220 = 22pF

221 = 220pF

4R7 = 4.7pF - etc.


J = 5%

K = 10%

M = 20% are the common ones,

There may be a letter to indicate tolerance:

So 474J = 470000 = 0.47uF = 470n