# what is a variable resistor

January 1st,
2021

When a variable resistor is used as a potential divider by using 3 … Definition of Variable Resistor It is an electronic component. The control is called a VARIABLE RESISTOR when the wiper is connected to one end of the track, effectively making it a two terminal device having a variable amount of resistance across the two terminals. Mostly two types of taper are marked, namely linear and logarithmic taper. A variable resistor is a device that is used to change the resistance according to our needs in an electronic circuit. A variable resistor, although used in different industries, is used in a relatively similar way. As the resistance of the resistive track changes, the voltage across the load changes. These aren’t the rotary kind of potentiometers like you have with light dimmers. Some examples of variable resistors are the volume control knob on a radio and a dimmer switch used for a light. As the wiper contact slides away from the connected end of the resistance track, the resistive value of the resistor increases and current goes down through the circuit. taper indicates that the relation between the two is linear, meaning the resistance ratio will be directly proportional to the mechanical position. They are used as rheostats. In a logarithmic track, the halfway point of the element is not one-half total possible resistance. of the resistor. A variable resistor is the type of resistor which changes the flow of current in a controlled manner by offering a wide range of resistances. By adjusting its internal configuration, we can obtain variable resistance at the load side. The resolution is nothing but the smallest value of resistance through which a  variable resistor changes. The linear resistors are two different types of resistor which are the following. This means the relation between the mechanical position and the resistance ratio is logarithmic, when plotted in a graph. of terminals = 3 2. A resistor is a passive circuit element which decreases the current flow and/or drops the voltage on purpose. It provides a variable value of resistance across electrical circuits. . It can be used as a three-terminal as well as a two terminal device. It is usually used in the circuit that needs to adjust the resistance frequently and plays the role of adjusting the voltage, adjusting the current, or controlling the signal. This means the relation between the mechanical position and the resistance ratio is logarithmic, when plotted in a graph. By adjusting the wiper terminal, it can be used to represent a wide range of resistances in a circuit from anywhere near 0Ω to the specified resistance rating of the potentiometer. Variable Resistors can also be found in Audio control, Television, Motion control, Transducers, Computation, Home Electrical Appliances, Oscillators, sensors etc. The most common type of V.R is shown below. Connecting in this way helps to reduce or increase the current through the circuit by just changing the position of the moving wiper. If the resistance of the current value is directly proportional to the applied voltage is called the linear resistance. Here, the two fixed terminals are connected across a voltage source. Although both potentiometer and rheostat are same devices, the names potentiometer is given to configuration when a variable resistor is set to provide a variable voltage on the output. Here, in this article we shall discuss about variable resistors, its definition, types and uses. When it has two terminals, it acts as a variable resistor… Here one of the fixed terminals and the moving terminal is used. A variable resistor with a resolution 0.005 means, that the smallest value by which the resistance changes is 0.005 ohm. There’s another important characteristic of a variable resistor which one needs to know before choosing a resistor for a specific application. Based on the material used for construction, potentiometers are classified into two types, It is this feature which decides the geometry of a potentiometer. Depending on the construction of the resistor, the wiper will often be controlled with a sliding switch or knob. Variable resistors can be categorized into three types: Its position cannot be seen or confirmed , therefore a stopping mechanism is needed to be integrated to prevent over rotation. An insulating substrate is wound by nichrome wire. The resistance will change based on where the wiper contacts the element. The resistive track can be of an arc shape or can be a straight one. We usually refer Potentiometer as a POT. A variable resistor allows for finer control over current by changing the amount of resistance. It divides voltage in ciruit. Therefore, in applications where current control or voltage control is needed, these type of resistors come handy. They can also be used to … As a variable resistor, it serves to vary the amount of voltage or current in a circuit. A typical variable resistor has 3 terminals. The terminals are made of conducting metal. When resistance decreases the flow of the current increases. Variable resistors are resistors that change resistance from zero to a certain maximum value. A variable resistor allows more control over current flow by changing the amount of resistance. They’re the push button variety. Out of the three, two are fixed terminals at the ends of a resistive track. We can connect any three terminal variable resistors (mostly potentiometer) as a rheostat too. There are two common types of resistor; fixed and variable resistors. A very stable type of material, it has a low temperature coefficient and is highly resistant to temperature. It can be directly mounted on circuit and mostly its value is adjusted only once during the calibration process of the circuit. The resistive strip can also be laid down in a straight manner and the wiper in this case is called a slider. A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. Magneto Resistor – Symbol, Working, Types & Characteristics, Carbon Film Resistor – Working, Construction & Applications, Photoresistor – Symbol, Working, Types & Applications. The resistor values are changed with the help of the temperature and applied voltages are called linear resistors. Presets are mostly mounted in calibration circuits. As resistance increases, the amount of current decreases. A potentiometer is a 3-terminal variable resistor. It is done by wiring the other unused fixed terminal and the moving terminal together, as a single terminal. The rheostat is represented by the symbol shown in figure: The preset is represented by a symbol shown in figure below: Variable resistors are mostly used where voltage control and current limiting is needed. one end of the resistance track and wiper terminal are connected with the circuit, so that the current through the resistor limits according to the position of the wiper contact on the resistance track. Potentiometer Kit - 5pcs Multi-Turn Trimmer (1K -100K Ohm), 10pcs Single-Turn Linear Variable Resi… A digital potentiometer is a variable resistor which is controlled by digital signals instead of by mechanical movement. Variable resistor: One of the major applications of a pot is a variable resistor or adjustable resistor. Connecting in this way helps to reduce or increase the current through the circuit by just changing the position of the moving wiper. The variable resistor means its resistance value can be adjusted (similar to a potentiometer). For example, a 9 kΩ V.R will provide resistance ranging between 0-9k. LDR is an acronym for Light Dependent Resistor, so… Typically, a variable resistor means a potentiometer or trimmer potentiometer. Variable resistors have two basic components. I have one in my master bedroom. That is if there is an increase in resistance, the current through the circuit will decrease. In the potentiometer the resistance of the track remains the same as the wiper moves, and only the potential on the wiper changes. A variable resistor works by adjusting the path that current has to flow. : When a variable resistor is used in a circuit to control the current flow, it is known as a rheostat. This is the latest variable resistor circuit symbol specified by the national standard. A rheostat is the simplest type of variable resistor, designed to handle the full current of the circuit. It has a voltage dividing property, which helps to find out the electrical emf. 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. Variable resistors are mostly used for device calibration. Another example is a variable capacitor. One of the critical pieces in an electric circuit, the resistor is the most omnipresent electronic component. Mostly they are used as a three terminal device. The code on the bottom varies but the last part of each code is N4A . The element in a potentiometer is usually a carbon film. Our webiste has thousands of circuits, projects and other information you that will find interesting. The light dimmer basically varies the voltage that is sent to the lamp that is being controlled. The resistive material can be either of the following types: Now that the working principle has been discussed, let’s have a look into the characteristics of a variable resistor. Their use is limited as they are really costly, and can be used in low power applications only. I believe they use switches. A high resolution is a favourable characteristic of a variable resistor. Types of Variable Resistors Potentiometers. A variable resistor is a resistor of which the electric resistance value can be adjusted. It usually has three terminals, one of which is used for reference voltage, which increases precision. When resistance increases in a variable resistor, the amount of current that is allowed to flow in a circuit decreases. To complete the circuit, the wiper makes contact anywhere along the length of the element. As resistance increases, the amount of current decreases. The resistance here varies in a logarithmic manner. The basic form of POT can represented as: Features of Potentiometer 1. A potentiometer is a variable resistor that allows much finer control than a rheostat, because it also functions as a voltage divider. The variable resistor is represented by a zig-zag line and an arrow across (or above) it, like that shown in the figure below. It is known as the. Preset resistor is a variable resistor that is only operated during menufacturing and tuning a circuit. As the resistance changes, the current changes inversely. A variable resistor allows for finer control over current by changing the amount of resistance. The load circuit here is connected across the wiper terminal. eval(ez_write_tag([[250,250],'circuitstoday_com-large-mobile-banner-1','ezslot_19',126,'0','0'])); CircuitsToday.com is an effort to provide free resources on electronics for electronic students and hobbyists. The third fixed terminal is left unused. Some examples of variable resistors are the volume control knob on a radio and a dimmer switch used for a light. There’s another important characteristic of a variable resistor which one needs to know before choosing a resistor for a specific application. Here the voltage source is connected across the resistive track that is it is connected across the two fixed terminals. A regular capacitor would let you store electrical charges. This is particularly used in circuits where control of voltage is needed. It is known as the resolution of the resistor. A variable resistor is used because a potential divider with 3 terminals is known as a potentiometer. The output circuit is connected across the moving terminal. Hence it is also called as adjustable voltage divider. As we move the wiper towards terminal 3, we see that the effective length decreases. Two basic components make up variable resistors. They are commonly used as volume controls and in voltage regulators. Now that we have discussed the main characteristics of the variable resistor, let’s now have a look into the types of variable resistor. Obviously you would expect to see these things in electronic components as everything is pretty much stuck onto an electronic circuit board, without the need for much wiring. This image showing a variable load resistor available for the experimental purpose in labs. When the ends of the resistor track connect with inputs of circuits, a … It is the position of this terminal on the resistive track that decides the resistance of the variable resistor. Changing the resistance as a user is actually very simple. For example, every time that you use a light dimmer for a room, you’re using a variable resistor. It looks like a voltage divider circuit, as shown below. However, their inaccuracies of operation lead to the makers look for other alternatives. As shown in Figure, it is a three terminal variable resistor. 3. This means that they help connect circuits while leaving the resistance track open. In an electrical circuit, a resistor acts as a fixed restriction to current flow without switching the current completely on or off. As the wiper contact slides away from the connected end of the resistance track, the resistive value of the. It consists of a resistor and a rotating or sliding system. In this video I have describe about what is variable resistor, different parts of variable resistor and how we test variable resistor. As the wiper passes over the coil, resistance increases or decreases. Their only drawback is that they have limited resolution. The most important characteristic of a variable resistor is given by the relation between the mechanical position of the moving terminal and the resistance ratio. Digital potentiometers are integrated circuit (ICs), some variants have a nonvolatile memory (EEPROM) which remembers the 'wiper' position. They help in tuning radios and they’re called tuning capacitors. eval(ez_write_tag([[580,400],'circuitstoday_com-medrectangle-3','ezslot_15',108,'0','0']));When we use the term variable resistor, it means we are talking about linear resistors by default. @everetra - Yeah, I think anything that’s variable from an electronics perspective will work the same way. A variable resistor with a resolution 0.005 means, that the smallest value by which the resistance changes is 0.005 ohm. is called a slider. Visually, the element is the most recognizable part of a rheostat. It is marked on the resistor as its taper. Yes, that’s exactly what is used here. The position of the movable contact determines the resistance value in the circuit. In applications where voltage control is needed, the potentiometers are preferred as their connection suits for the same. The connection and purpose of a variable resistor in a circuit, determines the type of variable resistor. These components are all the same size and have the same plastic mounts. Learn about a little known plugin that tells you if you're getting the best price on Amazon. 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. Rheostats are generally larger than potentiometers because of the loads they must carry. A variable resistor is the type of resistor which changes the flow of current in a controlled manner by offering a wide range of resistances. This means the voltage drop across the whole resistive track, is nothing but equal to the voltage source. The resistive strip can also be laid down in a straight manner and the wiper in this case. These POT are available in different values. I think I should point out that there is also the digital variable resistor which doesn’t rely on mechanical parts to change its resistance. The dial you turn will move another piece of wire inside the resistor. The resolution is nothing but the smallest value of resistance through which a  variable resistor changes. This when drawn in a graph, will have a straight line with a constant slope. The other type of taper is the logarithmic taper. They differ from potentiometers in the fact that they only have two leads of which potentiometers have 3. Is Amazon actually giving you the best price? If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat. Rheostats and potentiometers are two common types of these devices. The circuit is directly wired to the element and to the wiper. Therefore, the main part of a typical variable resistor is the resistive material. It does the same thing that a regular component would do but it just lets you vary the input. A variable resistor's role in a circuit is to allow the amount of resistance to be changed. 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