What is the resistor and what it is for
Perhaps the most widely used in electronics element is a resistor or as it is called in a simple way - resistance. If you look at absolutely any scheme, you will find more than one resistance. And how the resistor and what it is about this and talk in this article.
Content
Determination and designation according to GOST
existing varieties
How does the resistor
The main characteristics
Application area
conclusion
Determination and designation according to GOST
So, first let's define our element with you. Resistor (from the Latin "Resisto") is literally translated as "resist." Even becomes clear from the name of the element main task - to resist flowing through the electric current element.
Resistance refers to a class of passive elements, i.e. it can only restrict the passing current and voltage. Symbol accordance with the GOST 2.728-74 presented below:
existing varieties
Classification resistors carried on several parameters, for example, by the method following the modification distinguish Manual:
1. excretory. This is a classic and popular option is used to mount through a circuit board. This design resistors are still used in simple applications where the use of SMD components impractical or impossible.
2. SMD. In these resistances do not have the usual "legs". These elements are created for the installation of automated systems, which greatly speeds up and simplifies production.
According resistors manufacturing techniques are the following:
1. wire. In these resistors as a resistive element protrudes wound on a core wire and in order to reduce the parasitic inductance, bifilar winding is used. In such wire resistances used with low resistivity and temperature coefficient.
2. Metallized and composite. The data elements as resistive elements are the films of specialized alloys.
The following materials are used mainly
And SMD elements or chip - resistors are produced thin-film or thick-film and as a resistive material applied
Structurally resistors differ by:
1. standing. The magnitude of resistance such resistance is set during production and is not changed.
2. variables. This so-called trimming resistors and potentiometers. Such products present governing body, with which you can change the resistance.
3. nonlinear. Such resistance element varies depending on factors affecting the product, for example, under the influence of temperature, light, stress, etc.
There are also resistors for special applications: high-impedance, high-frequency, precision (products with a very high accuracy class).
How does the resistor
Do you realize the main purpose of the resistor - the restriction of passing electric current through it. And in this case, running the Ohm's law:
U = I * R
let us imagine the most common flexible water hose through which the water flows under the pressure, and now lay on the brick hose for ease of understanding the principle of operation of the resistor. Since the tube diameter has changed from the hose implies minimal amount of water. And a current: passing through the resistor, its value decreases.
Thus, current flows through the resistor and the voltage drop occurs. From this it can be concluded that part of the power passing through the resistance was converted into thermal energy. Power can be calculated using the following formula:
P = I ^ 2 * R
It happens because the power dissipation in the resistor is very important to choose such resistance to be stably operated at a long finding products under load.
Note. Resistors are chosen with a margin of capacity of 20% -30%.
The main characteristics
The main characteristics of absolutely any resistor are the following three values:
1. Resistance
2. Maximum power dissipation.
3. Class of accuracy or tolerance. From this parameter depends on how much actual product specifications may vary and passport data.
Application area
So, you already know that the resistor performs the current limiting function of the circuit. The simplest example of such limitation is a conventional LED connection circuit. Limiting the magnitude of resistance in this case is calculated by the formula:
Just resistor may act as a voltage divider. The output voltage is calculated by the following formula:
Even with a resistor can be set current of the transistor, which in fact is the same limitation:
conclusion
This is just a small fraction of the information about this seemingly simple and complex at the same time as a resistor element. If you want to know more, you can always subscribe to a channel or to find information you are interested in the specialized literature.
Thank you for your attention!