Variable resistor and its application area
Variable resistor or, as it is also called,The rheostat is designed to adjust the resistance of the electrical circuit in order to obtain the desired value. Depending on its design features, it can change the resistance both smoothly and in stepwise order.
Usually a variable resistor is used invarious kinds of equipment and devices. It can be seen as a volume knob, as a lighting control, etc. At the same time, its application area is so large that at the present time there is practically no electrical device that, one way or another, would not be equipped with a variable resistor.
There are four main types of rheostats, which differ from each other constructively, but perform the same functions.
The first type represents wire resistors. They are very common and can clearly show the operation principle of all variable resistors. The essence of their work lies in the fact that the wire wound on the frame is energized, and with the help of the third contact it is removed from different places of the frame. Naturally, in every concrete place resistance will be different.
The second type is a variable resistorslider. It is made of wire, which has a large intrinsic resistance, it is regulated in the same way as in wire resistors. However, there are differences. In the wire resistor, the voltage is removed from the contacts, which provides a step change in the resistance, and in the slider this change occurs smoothly, since the slider freely slides along the wire.
The third type is a variable resistor that uses an electrolyte. To do this, the resistor contacts are immersed in it, and the adjustment is made by changing their distance.
One of the most intuitive and simple typesvariable resistors is a tube. It consists of parallel connected lamps, and the resistance changes in it by turning them off or on. Such a variable resistor is very inaccurate and unreliable, since its values directly depend on the degree of lamp heating, and therefore can vary with time.
It is worth noting that due to the rheostat it is possibleChange not only the resistance, but also the strength of the current and voltage. For this, the variable resistor is connected to the electrical circuit in parallel or in series, depending on the need to change a particular parameter.
Thus, the variable resistors usedfor regulating the amperage, can be called rheostats, and resistors for voltage regulation are called potentiometers. It is these that are used as regulators for sound volume, output voltage, power, etc. On their basis, a large number of different types of linear and angular displacement sensors have been constructed.
Due to their qualities and properties, variable resistors are considered one of the foundations of modern electronics and electrical engineering.
