Resistor rating - recording methods

Resistors are elements of electrical circuits that have resistance to the passage of an electric current. They are used in all electrical circuits, even in the most elementary ones. There are resistors for the following features: power, the value of the nominal resistance, accuracy class, type, etc. In this article we will consider such a concept as the value of the resistor. What it is? The nominal value of the resistance element means the value of the level of internal resistance to the passage through it of an electric current. In electrical engineering, the value of the resistor is denoted by the Latin letter R. It is customary to write this value in units such as Ohm. This unit received its name in honor of the famous German physicist Georg Simon Ohm, known for his work in the field of the study of electric current. Why do I need to know the value of the resistors? What would be the right choice of elements for the projected scheme or choose an analog for repairing devices.

Let's consider ways of recording the nominal values of resistances on the case of elements. There are three ways of labeling resistors: digital - includes only numbers; Symbolic - is combined, along with figures there are also letters; And, finally, color - it is a series of transverse bands of different colors, the number of bands varies, from 3 to 5.

Next, we will analyze how the resistor's value is recorded, depending on the type of element. Constant resistance elements of wire type are a cylindrical barrel. These elements are marked in all three ways. Digital recording is used only for resistors whose nominal value does not exceed 999 ohms. It looks like this: 2.0; 220; 750. Means, accordingly: 2 Ohm, 220 Ohm and 750 Ohm. The following kind of record uses Latin characters instead of a comma : R - means one; K is kilo, i.e. 1000; M - mega, that is 1000000. It turns out that with this method of recording, in order to obtain the value of the resistor, the numerical value must be multiplied by the value of the letter. An example of such a record: 220 R - means 220 Ohm; 3K2 - means 3200 Ohm; 1M1 - means 1100 kΩ.

The color coding of the nominal value recording is applied across the cylindrical body of the element. In Soviet-made resistors, the marking was applied with a shift to one side, this indicated the beginning of the decoding count. In modern elements, the last barcode bar is always gold or silver, and it means the resistance accuracy class (5 or 10 percent). In the event that the marking consists of only three bands, the default accuracy class is 20 percent. Encoding, consisting of 3-4 bands, in the first two contains the value of the nominal value, and the third - the value of the multiplier. The encoding of 5-6 bands in the first three contains the value of the nominal, and in the fourth - the value of the multiplier.

The next kind of resistance is a chip resistor or an SMD resistor. In such resistors, the marking can be digital and symbolic. It is simply deciphered: in the digital marking, the first digits indicate the value of the denomination, and the last one indicates the number of zeros; In the symbolic - the first two digits indicate the denomination, and the last character indicates the value of the multiplier.

The variable resistors use the standard nominal value recording with the help of numbers and letters of the Latin alphabet.