What kinds of resistors exist?

When creating technical schemes, details are needed. Resistors are one of the most important. It is difficult to imagine a diagram even for five details, wherever they find their application.

What is a resistor

This term was created thanks to the Latin"Resisto", which can be translated as "resist". The main parameter of these elements, which provides interest, is the nominal resistance. It is measured in Ohms (the number of Ohms). The nominal values ​​indicate the device casing. But the real figure may be somewhat different. Usually this nuance is provided by using classes and tolerance tolerances. We will now consider them. If you have something that is not clear about the types of resistors, the photo will help fix it.

Classes and tolerance tolerances

In the general case, the most interesting are the classes. There are three:

1. First. Provides for deviations of up to five percent of the nominal value.
2. Second. Provides for deviations, which can reach ten percent of the nominal value.
3. The third. This includes devices in which the size of the deviation can reach twenty percent of the nominal value.

And what if such large deviations are unacceptable? There are precision resistors, the types of which provide such a maximum difference:

1. 0.01%.
2. 0.02%.
3. 0.05%.
4. 0.1%.
5. 0.2%.
6. 1%.
7. 2%.

Other options

Significant importance in the choice of an element forthe circuits have the values ​​of the limiting working voltage, the rated power dissipation and the temperature coefficient of resistance. The last figure shows how much the changes in the degree scale will affect the operation of the device. Depending on the material used in the production, this indicator may increase or decrease. The nominal dissipation power indicates the limits of the use of the element. If the supplied characteristic is greater than can be processed, the resistor may simply burn out. Under the limiting operating voltage is understood such an indicator, at which reliable operation of the device will be ensured.

Main types of resistors

They are distinguished by four:

1. Unregulated:

a) are constants.

2. Unregulated:

a) trim;

b) variables.

3. Thermoresistors.

4. Photoresistors.

Unregulated fixed resistors in additionare divided into non-wire. The latter type is additionally wound around the wire so that they have a high resistivity. Constant resistors are depicted in the form of rectangles, from which there are special conclusions. The amount of permissible power dissipation is indicated inside the geometric figure. If the resistance value is in the range from 0 to 999 ohms, the units of measurement are usually not indicated. But if this indicator is more than a thousand or a million, then the notation kOhm and MOhm, respectively, is applied. If this indicator is specified only approximately or it can change during the setting, then add *. Due to this, the types of resistors of different parameters easily differ among themselves.

Variables

We continue to consider the types of resistors.This type of device can also be called adjustable. In them, the resistance can vary from zero to nominal. They can also be non-wired. The first is a conductive coating that is applied to the dielectric plate as an arc where a spring contact moves, which is fixed to the axis. If you want to change the resistance value, it is moved. Depending on a number of features, this parameter can vary according to these dependencies:

1. Linear.
2. Logarithmic.
3. Indicative.

Trimmer Resistors

They do not have a protruding axis.Changing the parameters of this type of resistors is possible only with a screwdriver or an automatic / mechanical device that can perform its functions. This and the previous type of resistors are used in cases where a person must regulate their power, for example, in sound columns.

Thermoresistors

So called semiconductor elements, withInclusion of which in the electrical circuit such an indicator as the resistance, varies with temperature. When it increases, it goes down. If the temperature decreases, the resistance rises. If the process curve moves in one direction (increases with increasing), then such an element is called a posistor.

Photoresistors

This is the name of the elements for which the indicatorparameter varies under the influence of light (and in some cases, electromagnetic) radiation. As a rule, photoresistors with a positive photoelectric effect are used. At them resistance decreases, when on them the light falls. Photoresistors have a simple design, small size and high sensitivity, which allows them to be used in photocells, counters, control systems, control and regulation devices, sensors and many other devices.

Conclusion

Here such there are resistors, kinds, purpose, a principle of work of the given devices.