Kitronik 2143K - Page 14

High Power Amp Teaching Resources
www.kitronik.co.uk/2143
Calculating resistor markings
Calculate what the colour bands would be for the following resistor values.
Value
1st Band 2nd Band Multiplier x
180 
3,900 
47,000 (47K) 
1,000,000 (1M) 
What does tolerance mean?
Resistors always have a tolerance but what does this mean? It refers to the accuracy to which it has been
manufactured. For example if you were to measure the resistance of a gold tolerance resistor you can guarantee
that the value measured will be within 5% of its stated value. Tolerances are important if the accuracy of a resistors
value is critical to a design’s performance.
Preferred values
There are a number of different ranges of values for resistors. Two of the most popular are the E12 and E24. They
take into account the manufacturing tolerance and are chosen such that there is a minimum overlap between the
upper possible value of the first value in the series and the lowest possible value of the next. Hence there are fewer
values in the 10% tolerance range.
E-12 resistance tolerance (± 10%)
10
12
15
18
22
27
33
39
47
56
68
82
E-24 resistance tolerance (± 5 %)
10
11
12
13
15
16
18
20
22
24
27
30
33
36
39
43
47
51
56
62
68
75
82
91