> # Appendix A.

> ## Standard Values for Electronic Components.

> Resistors, capacitors, some lines of RF chokes, and zener diodes come in standard values. The numbers may seem rather strange but they are based on a geometric series which will be explained later.

> There are sets of values for tolerances of plus or minus 5%, 10% and 20%. The table below gives the standard values for the decade between 10 and 91. A value an any other decade can be obtained simply by multiplying a number from the table by the appropriate power of 10.

> 5% | 10% | 20%
> 10 | 10 | 10
> 11 | NV | NV
> 12 | 12 | NV
> 13 | NV | NV
> 15 | 15 | 15
> 16 | NV | NV
> 18 | 18 | NV
> 20 | NV | NV
> 22 | 22 | 22
> 24 | NV | NV
> 27 | 27 | NV
> 30 | NV | NV
> 33 | 33 | 33
> 36 | NV | NV
> 39 | 39 | NV
> 43 | NV | NV
> 47 | 47 | 47
> 51 | NV | NV
> 56 | 56 | NV
> 62 | NV | NV
> 68 | 68 | 68
> 75 | NV | NV
> 82 | 82 | NV
> 91 | NV | NV

> Note, NV = No Value for this tolerance.

> ### Why these strange values?

> Let's take a 10 ohm 10% resistor as an example. That resistor could have any value between 9 and 11 ohms. It wouldn't make any sense to have an 11 ohm 10% resistor. That resistor could be anything between 9.9 and 12.1 ohms. The next higher 10% value is 12 ohms which may be anything between 10.8 and 13.2 ohms. True, there is a slight overlap but resistor values only have 2 significant digits and the next step up, 13 ohms would leave a substantial gap. The values are stepped so the tolerances just touch or overlap

> 1/4 watt 5% resistors are manufactured in values from 1 ohm to 10 Meg ohms

> Back to Fun with Transistors.
> Back to Fun with Tubes."
> Back to Table of Contents.

> This page copyright © Max Robinson. All rights reserved.