They are mostly used in high power applications, have a long life and are precise. Wire wound – An insulating substrate is wound by nichrome wire.However, their inaccuracies of operation lead to the makers look for other alternatives. Its low cost, reasonably low noise and lesser wear than other materials made it popular among the manufacturers. Carbon Composition : One of the most common type, this material is made from carbon granules.The resistive material can be either of the following types: Therefore, the main part of a typical variable resistor is the resistive material. Its position cannot be seen or confirmed, therefore a stopping mechanism is needed to be integrated to prevent over rotation. The resistive strip can also be laid down in a straight manner and the wiper in this case is called a slider.
So what will happen to the resistance offered by the pot? It will decrease. As we move the wiper towards terminal 3, we see that the effective length decreases. Our point of focus is the second length, as that is what decides the output of the resistor. Let’s suppose the wiper is placed at position “a”, we can say that it divides the resistive track into two tracks of different lengths, from terminal 1 to point a and the other track being from point a to terminal 3. The arrow placed on the resistive strip (arc shaped track), indicates the current position of the wiper terminal. Recall your basics of resistance the resistance of a material is directly proportional to the length of the material. To do so, a resistive strip is placed in between two fixed terminals of the device, a third terminal which is a movable one, is made to glide over this strip. These resistors offer a different resistance value, which means their resistance values can be adjusted to different values so as to provide the necessary control of current and/or voltage. It is the position of this terminal on the resistive track that decides the resistance of the variable resistor. The other terminal is a moving terminal, mostly known as the wiper. The terminals are made of conducting metal. Out of the three, two are fixed terminals at the ends of a resistive track. The voltage and current follow ohm’s law and are proportional to each other.Ī typical variable resistor has 3 terminals. Linear resistors, as we know are those resistors whose resistance remains constant, even when the voltage and current through it changes. When we use the term variable resistor, it means we are talking about linear resistors by default. Variable Resistor: Working Principle and Construction The variable resistor is represented by a zig-zag line and an arrow across (or above) it, like that shown in the figure below. Figure 1 shows some real life variable resistors. Therefore, in applications where current control or voltage control is needed, these type of resistors come handy. They can also be used to control the voltage across devices in a circuit too. As the resistance increases in the variable resistor the current through the circuit decreases and vice versa. Let’s start! What is a Variable Resistor?Ī variable resistor is the type of resistor which changes the flow of current in a controlled manner by offering a wide range of resistances. Here, in this article we shall discuss about variable resistors, its definition, types and uses. Resistors are broadly classified as fixed and variable resistors, according to the type of resistance value they offer. Available in wide varieties, these resistors can be used in various applications. One of the critical pieces in an electric circuit, the resistor is the most omnipresent electronic component. Variable Resistor – Working, Construction, Types & Applications