Basic radio theory, circuits and calculations

Tolerance and effect of temperature on components

These are important aspects of all electronic components, particularly resistors and capacitors.

Tolerance
The tolerance on the value of a component is a measure of how accurate its value is. For example, a resistor of nominal value l0,000, and a tolerance of±10%, may have an actual resistance between 9,000 (ie 10,000- l0%)and 11,000 (ie 10,000+ 10%). The usual tolerances on the values of resistors and capacitors are ±20, ±10, ±5, ±2 and ±1%.

Temperature effects 

Generally the value of a component increases as the temperature increases. A constant known as the 'temperature coefficient' is a measure of this increase, and thus (for most items) the temperature coefficient is positive.

There are a few exceptions, eg ceramic capacitors having a negative temperature coefficient can be made. Carbon and semiconductors have a negative coefficient.

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