TechnologiesElectronics

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 body. But the real figure may be somewhat different. Usually this nuance is provided with the help of 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 classes are of greatest interest. There are three of them:

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

And what if such large deviations are unacceptable? There are precision resistors, the kinds 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 selection of the element for the circuit has the parameters of the limiting operating voltage, the nominal power dissipation and the temperature coefficient of resistance. The last indicator shows how 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 power dissipation indicates the limits of the use of the element. If the supplied characteristic is greater than can be processed, the resistor can simply burn out. Under the limiting operating voltage is understood such an indicator, in 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.

Non-adjustable permanent resistors are further divided into non-wire resistors. On the latter type, the wire is additionally wound up, so that they have a high resistivity. Permanent resistors are represented in the form of rectangles, from which there are special conclusions. The amount of permissible power dissipation is indicated inside the geometrical 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 still be called adjustable. In them, the resistance can vary from zero to nominal. They can also be non-wire. The first view 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

This is what semiconductor elements are called, when switched on, the indicator, such as resistance, changes from temperature to the electric circuit. As it increases, it goes down. If the temperature decreases, the resistance rises. If the process curve moves in one direction (increasing with increasing), then such an element is called a posistor.

Photoresistors

This is the name of the elements whose parameter of the parameter varies under the influence of light (and in some cases electromagnetic) radiation. As a rule, photoresistors with a positive photoelectric effect are used. Their resistance decreases when light falls on them. Photoresistors have a simple design, small dimensions 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 operation of the given devices.

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