What is the tolerance in resistors?
I was told an interesting fact about resistor tolerance by my electronics teacher in school. Basically, you will never find a 5% tolerance resistor with the resistance it claims. Resistors are made to be, for instance, 50 ohms. Once the resistors have been made they are tested. Some of them may be 18 or 476 ohms, and they will be scrapped. Some are 48 or 53 ohms, and they are sold as “50 ohm 5% tolerance”. If they are 50.02 ohm, however, they will be sold as “50 ohm 1% tolerance” resistors which get a higher price. The upshot of this is, if your resistors are available in 1% and 5%, then “5%” tolerance resistors will be between 1% and 5% different from their rated value. This may or may not be representative of current industrial practice, and might have been false but used as an example to teach us the value of testing your components for true rather than indicated value, but it’s something to think about anyway. If the value of your resistors is crucial, test them until you find one
