Resistor - this is the main element of radio electronics

Resistor - this is the simplest element of radio electronic circuits, which has the property of providing resistance to the electrical current flowing through it. The name of this device came from the English word resist, which means resistance.

The nominal resistance of the resistor is measured in Ohms (Ohm, kOhm, mOhm), in honor of the scientist George Ohm, who discovered the law, according to which the resistance of the electrical circuit is equal to the ratio of the voltage to the current of the circuit.

The industry produces resistors with different values of the nominal resistance. There are three main types of these instruments: permanent, variable, trim.

A constant resistor is the most numerous class of elements that have unchanged resistance. The body of such a device is marked with a signifying the type of resistor, the value of the nominal resistance, accuracy class, power dissipation, etc. This information is coded in various ways. So, you can see the elements, in which all the data is recorded with the help of color marking (from three to seven color cross strips). To read these values, you need to use a special table, which can be found in the reference literature or in the technical description of these elements. The second type of record is alphanumeric. In this way, information is transmitted using symbols and numbers. So, a 10 ohm resistor can have the following marking: MLT 10R. MLT means the type of device.

A variable resistor is a device having a certain range of nominal resistance. On the body of this element there is an adjusting element (screw or rotary knob), with which you can set the necessary resistance of the device. On such devices, the nominal value marking is indicated in alphanumeric form - the limit from the minimum to the maximum resistance value is indicated. Such devices are widely used to adjust and adjust signals: as tone controls, levels, volume, tuning to the frequency in the radio receiving equipment.

Trimmer resistor is an instrument having a certain range of nominal resistance, but unlike variables, this range is insignificant. Such elements have found wide application in radio electronic circuits. They are designed to adjust and fine-tune the required parameters when designing radio equipment or in high-precision devices where the dispersion of characteristics is not allowed. They allow you to accurately set the required resistance, as a result, there is no need to solder-solder the resistors of a constant value to select the desired value.

In addition to the basic parameters, any resistor has a so-called parasitic characteristic - capacitance. What is this parameter? The parasitic capacitance of the resistor, as a rule, is very small and does not particularly affect anything. It must be taken into account only when designing high-precision equipment. A parasitic capacitance is present between the terminals of the element; It turns out that the capacitor is soldered in parallel with the resistor. Also, a capacitance can arise between the resistor and adjacent parts of the PCB and parts of the structure.

On this brief overview of such an element as a resistor we finish, more detailed information can be found in the textbooks on industrial electronics.