As an indispensable basic component in electronic circuit, the resistance value is related to the working state of the circuit. How to view and judge the resistance value of a resistor is a basic skill for electronics enthusiasts and engineers. This article will introduce several common methods to determine the size of the resistance value of a resistor.
1. Color coding method
Traditional carbon or metal film resistors take color ring coding to indicate their resistance value. The first three rings of the four-color ring resistance represent the number of resistance values, while the fourth ring represents the tolerance. Each color ring corresponds to a specific number, and by memorizing the code of these colors, we can quickly read the resistance value of the resistor. For example, the resistance of the red, black and red gold strip, red represents the number 2, black is 0, which is 20, and gold indicates a tolerance of ±5%, so the resistance value of this resistance is 20 ohms, and the tolerance is ±5%.
2. Numerical notation
Surface Mount technology (SMT) resistors Some modern resistors have numerical values printed on the surface. These markers are three or four digits, with the first two or three digits representing significant digits and the last digit representing the number of zeros that follow. For example, a resistor with the number "100" indicates that the resistance value is 10 ohms; The number "102" means that the resistance is 1000 ohms, that is, 1000 ohms.
3. Digital display method
Some digital multimeter or resistance tester readings function. When using these tools, just touch the two pins of the resistance to the test end, and the precise resistance value will be displayed on the device screen. This kind of method is simple and easy, especially suitable for the occasion of accurately measuring the resistance value.
4. Compare measurements
If no measuring tool is available, a reference resistance with known resistance values is also used for comparison measurement. The resistance value of an unknown resistor can be roughly estimated by inspecting changes in voltage or current in parallel or in series. Although these methods are not precise enough, they give fair estimates in some cases.
There are many ways to identify and judge resistance values, from traditional color coding to modern digital display, and each method has its own applicable scenarios. Whether it is electronic production or ordinary protection, mastering these basic identification skills is very useful. Through the accumulation of practice and experience, you will be more skilled in reading the language of resistance, and accurately obtain its resistance value parameters.
