What is a Ponsiometer?

The posiometer and reosta are elements that can change the resistance value with a mechanical system. You can find the pocinciometer lettering that we used in our Arduino series with mBlock here.

In addition to producing a voltage drop according to the Ohm law, resistors provide a constant resistance value that blocks or resists the flow of electric current around a circuit.Resistors can be produced with a constant resistance value in Ohms or a variable resistance value set by some external means.

The ponciometer is a rotating analog device generally called "pot", operated as a three-phase mechanical that can be used with a large variety of electrical and electronic circuits.They are passive devices, that is, they do not require a power supply or additional circuit to perform basic linear or rotary position functions.

Variable pontiometers are available in a variety of different mechanical variations, allowing easy adjustment to control a voltage, current or pre-charge.

The name "ponciometer" is a combination of thewordsPotential Differenceand Meteringfrom the early days of electronic development.


Today, posensiometers are much smaller and much more precise than older large and voluminous variable resistors, and as with most electronic components, they have many different types and names, ranging from variable resistance, preset, trimmer, reosta and, of course, variable potents.

But regardless of their name, all of these devices work exactly the same, as the output resistance values can be replaced by the movement of a mechanical contact or the bar given by an external effect.

In any format, variable resistors are often used to adjust the sound of a radio, the speed of a vehicle, the frequency of an oscilator, or to correctly adjust the calibration of a circuit. Different types of pocinciometers are available, single-turn and multi-turn.

The term "variable resistor" is often used together to describe the same component, but it is important to understand that the connections and operation of the two are different.However, both share the same physical characteristics in terms of bringing the two ends of an internal resistant path to contacts, in addition to a third contact connected to a moving contact called a "slider" or "wiper".




When used as a ponciometer, rod connections are made to both end, as shown.Afterwardthe position of the bar provides a suitable output signal (pin 2), ranging from the voltage level applied to one end of the resistant path (pin 1) to the voltage level applied to the other end (pin 3).

Ponsiometer, along the wayit is a three-wire resistant device that acts as a voltage divider that produces a continuously variable voltage output signal in proportion to the physical position of the bar.

Variable Resistance


When used as variable resistance, only one end of the resistance line (pin 1 or pin 3) andbar (pin 2).The position of the bar itself is used to change the amount of effective resistance that binds between the moving contact and the fixed end.

Sometimes with the unused end of the resistance line to prevent open circuit situationsit is convenient to make an electrical connection between the rod.

Then a variable resistance, the current presented to the connected circuit, along the wayit is a two-wire resistant device that provides an infinite number of resistance values that control in proportion to the physical position of the bar.Note that a variable resistance used to control very high circuit currents in lamp or engine loads is called Reosta.

Types of Ponciometers

Variable polineometers are an analog device consisting mainly of two main mechanical parts:

  • 1. A constant resistance element that defines the resistance value of the pocinciometer, such as 1kΩ (1000 ohm), 10kΩ (10000 ohm), etc.
  • 2. A mechanical part that allows a bar or contact point to move from one end to the other along the entire length of the resistance path, changing the resistance value as it moves.

There are many different ways to move the rod along the mechanically or electrically resistant path.

But in addition to the resistant part and bar, posimetometers also consist of a enclosedter, a shaft, a sliding block and a bushing or bed.The movement of the sliding wiper or contact itself can be a rotating (angular) motion or a linear (straight) motion.The variable potencyometer has four basic groups.

Rotary Pontiometer


The rotary pocinciometer (the most common type) changes resistance values as a result of an angular movement.Rotating a button or dial connected to the shaft causes the built-in bar to move around a curved resistant element.The most common use of the rotary pocinciometer is the sound control pot.

Carbon rotary ponciometers are designed to be mounted on the front panel of a case, housing or printed circuit board (PCB) using a ring nut and locking rondel.In addition, they can have a single resistant part or multiple paths, all known as a grouped ponciometer, that rotates together using a single shaft.For example, it uses a dual-group pot to adjust the left and right volume control of a radio or stereo amplifier at the same time.

Rotary poxyometers can produce linear or logarithmic output, typically with tolerances of 10 to 20 percent.They can be used to measure the rotation of a spindle because they are mechanically controlled, but a single-turn rotary pocinciometer normally offers angular motion of less than 300 degrees from the minimum to the maximum resistance.However, there are multi-round potentsciometers called trimmers that provide a higher degree of rotational accuracy.

Multi-round pocentrometers allow spindle rotation in mechanical motion of more than 360 degrees from one end of the resistant road to the other.Multi-round posensiometers are more expensive, but very stable with high precision, which is mainly used for cropping and precise adjustments.The two most common multi-lap potnsiometers are 3 rounds (1080 o) and 10 rounds (3600 o), but 25-lap containers with 5 rounds, 20 laps and higher are available in various omic values.

Sliding Ponsiometer


Sliding ponciometers are designed to change the value of the resistance of parts that come into contact through a linear motion, and therefore there is a linear relationship between the position of the slider contact and the output resistance.

Slider ponsiometers are mainly used in a wide range of professional audio equipment such as studio mixers, faders, graphic equalizers and tone control consoles, allowing users to see the actual setting of the adjustment bar from the position or finger grip of the plastic square button.

One of the main drawbacks of the sliding ponciometer is that they have a long open slot to allow the wiper handle to move freely up and down the entire length of the resistant path.This open slot makes the resistant rail inside sensitive to contamination from dust and dirt or from sweat and oil from the user's hands.Corrugated seal covers and screens can be used to minimize the effects of resistant line contamination.

Since the posiometer is one of the simplest ways to convert a mechanical position to a proportional voltage, they can also be used as resistant position sensors, also known as linear displacement sensors.Sliding carbon potentometers, the sensor part of a linear sensor, measure a precise linear (straight) motion, which is a resistant element connected to a sliding contact.This contact is connected to the mechanical mechanism to be measured by means of a rod or shaft.Next, the position of the shoot changes according to the perceived quantity (measured size), which changes the resistance value of the sensor.

Trimmers and Trimmers


Trimmer or corrective ponsiometers are small "adjust and forget" type ponciometers that allow for very fine or occasional adjustments to a circuit (e.g. for calibration).Single-round rotary preset posimeters are miniature versions of the standard variable resistance designed to be mounted directly on a printed circuit board and are adjusted via a small screwdriver or similar plastic tool.

Presets can be set from minimum to maximum in a single round, but for some circuits or equipment, this small adjustment range can be too rough to allow very precise settings.However, multi-round variable resistors work by moving the rod arm using a small screwdriver, turning several rounds that allow for very fine-tuning from 3 rounds to 20 rounds.

Trimmer posiometers are multi-turn rectangular devices with linear rails designed to be mounted and soldered directly through a hole in a circuit board or mounted on the surface.This provides both electrical connections and mechanical assembly to the trimere, and placing the pallet in a plastic housing prevents dust and dirt problems during use associated with skeletal presets.



Reostas are large elements of the world of ponciometers.Two connections configured to provide any resistance value in omic ranges to control the flow of current from them are variable resistance.

In theory, while any variable potentialometer can be configured to work as a reostat, usually reostats are high voltage, wire-winded variable resistors used in high current applications, since the main advantage of the reostat is higher power ratios.

When a variable resistance is used as a two-pronged reosta, only the part of the total resistant element between the end terminal and the moving contact will dissect the power.In addition, unlike the potionometer configured as a voltage divider, the entire current passing through the reosta resistance element passes through the rod circuit.Then the contact pressure of the rod on this conductive element should be able to carry the same current.

Ponsiometers are available in various technologies such as carbon film, conductive plastic, sermet, wire wrap, etc. The rating or "resistance" value of a ponciometer or variable resistance relates to the resistance value of the entire fixed resistance path from one fixed terminal to another.Therefore, a 1kΩ grade pocinciometer will have a trace of resistance equal to the value of a constant resistance of 1kΩ.

In its simplest form, the electrical operation of a ponciometer can be considered the same as two resistances in series with floating contact, which changes the values of these two resistors, which allow it to be used as a voltage divider.

In our tutorial on Serial Connected Resistors, we found that the same current is serially phased out, as there is only one way the current will follow, and we can apply the Ohm Law to find voltage drops in each resistance in the series.

Voltage Divider Serial Circuit


In this example above, the two resistances are serially connected throughout the feed.Since they are serially connected, equivalent or total resistance, R T therefore equals the sum of two separate resistances, that is: R 1 + R 2 .

In addition, since there is a series of networks, the same current passes through each resistance, since the current has nowhere else to go.However, due to the different omic values of the resistors, the voltage drop given through each resistance will be different.These voltage drops can be calculated using the Ohm Act, whose totals are equal to the feed voltage throughout the serial chain.So here in this example, V IN = V R1 + V R2 .

Ponsiometer Question Sample 1

A resistance of 250 ohms is serially connected with a second resistance of 750 ohms, so that the resistance of 250 ohms is connected to a source of 12 volts and resistance of 750 ohms is connected to the soil (0v).Calculate total series resistance, serially circuitd current and voltage drop on 750 ohm resistance.


In this simple voltage divider example, it was found that the voltage generated in R 2was 9 volts.But by changing the value of any of the two resistors, the voltage could theoretically be any value between 0V and 12V.We can change the value of both resistances to achieve a different voltage output.

The difference with the ponsiometer this time is the total resistance of the resistance trace of the ponsiometer, the RT value does not change, only the ratio of the two resistances formed on both sides as the rod moves, in order to achieve different voltages at the output.


So far, we have seen that a variable resistance can be configured to work as a voltage dividing circuit called a ponciometer.But we can also configure a variable resistance to regulate a current, and this type of configuration is often known as Reosta.

Reostalar are two-terminal variable resistors configured to use only one end terminal and bar terminal.Unused end terminal can either be left unconnected or directlycan be connected to the bar.These are wire-winded devices containing tight heavy-duty enavor wire coils that replace resistance with step-by-step increments.By changing the position of the wiper on the resistance element, the amount of resistance can be increased or reduced, so that the amount of current can be controlled.

Then the reosta is used to control a current by changing the value of its resistance, making it a real variable resistance.The classic example of the use of a reosta is in the speed control of a model train set, the amount of current passing through the reosta is based on the Ohm Act.Reostalar are then defined as P = I 2 *R not only by resistance values, but also by their power processing capabilities.

Reosta as Current Regulator


In the diagram above, the effective resistance of the reosta is between the end terminal pin 3 and the wiper on pin 2. If pin 1 is left disconnected, the resistance of the line between pin 1 and pin 2 is open circuit and has no effect on the value of the load current. Conversely, if pin 1 and pin 2 are connected, that part of the resistant path will be short-circuited and again have no effect on the value of the load current.

Since the reostalar controls a current, by definition they need to be properly rated to handle this continuous load current.It is possible to configure a three-terminal poisterometer as a two-terminal reosta, but the carbon-based resistant line may not exceed the load current.Also, the rod contact of a ponciometer is normally the weakest point, so it is best to draw as little current from the rod as possible.

Usually reostats are high voltage electro-mechanical variable resistors that are used for power applications and whose resistance element is usually made of thick resistance wire suitable for carrying maximum current, with I when resistance R is minimal.

Wirewound reostas are mainly used in power control applications such as lamps, heaters or motor control circuits to regulate field currents for speed control or the starting current of DC motors, etc.


Sliding reostalar are the types found in school physics laboratories and science laboratories.These linear or sliding types use an insulating pipe-shaped shaper or resistant wire wrapped around the cylinder.The sliding contact (pin 2) mounted above is manually adjusted left or right to increase or decrease the effective resistance of the reostas, as shown.

As with rotary ponciometers, multi-group slider reostas are also available.In some types, resistant tele constant electrical connections are made to give a constant resistance value between any two terminals.Such interconnections are often known as "guides" with the same name as those used in transformers.

Linear or Logarithmic Ponsiometers

The most popular type of variable resistance and potentiometer is linear type or linear conical, which changes linearly when adjusted by producing a characteristic curve representing a straight line of resistance value in pin 2.So the resistant track has the same resistance change per angle of rotation along the entire length of the path.

Therefore, if the bar is rotated as much as 20% of its total movement, its resistance is 20% of the maximum or minimum.The main reason for this is that resistant trace elements are made of carbon composites, ceramic-metal alloys or conductive plastic type materials, which have a linear characteristic throughout their length.

But the resistance element of a potentiometer may not always produce a straight line characteristic when the rod is set, or it may not have a linear change in resistance throughout the entire range of motion, instead producing what is called a logarithmic change in resistance.

Logarithmic ponsiometers are mainly very popular among nonlinear or disproportionate types of poxiometers, whose resistance varies logarithmically.Logarithmic or "log" potentiometers are widely used as sound and gain controls in audio applications, where weight loss varies as a logarithmic ratio in decibels.This is due to the fact that the sensitivity of the human ear to sound levels has a logarithmic response and therefore is not linear.

Therefore, when the operation of a logarithmic ponsiometer is set, it is to produce an output signal very close to the nonlinear sensitivity of the human ear and sound as if the volume is increasing linearly.However, some cheaper logarithmic ponsiometers are much more exponential in resistance changes than logarithmics, but they are still called logarithmics because resistance responses are linear on a log scale.In addition to logarithmic poxiometers, there are also anti-logarithmic posimeters, whose resistance initially increases rapidly but is then balanced.

The best way to determine the type or law of a particular ponciometer is to adjust the center shaft to the center of its movement, that is, about half, and then measure the resistance in each semi, from the rod end terminal.If each half has more or less equal resistance, this is a Linear Ponciometer.If resistance appears to be divided by about 90% in one direction and 10% in the other, this is a Logarithmic Ponsiometer.


In this tutorial on ponsiometers, we found that a ponciometer or variable resistance consists mainly of a resistant track with a connection at both ends, and a third terminal called the bar, which divides the position of the bar and the resistance track.The position of the bar on the pallet is mechanically adjusted by rotating a shaft or using a screwdriver.

Variable resistors can be categorized into one of two operating modes – variable voltage divider or variable current reosta.The ponciometer is a three-terminal device used for voltage control, while the reosta is a two-terminal device used for current control.

We can summarize this in the following table:

ConnectionsThree TerminalsTwo Terminals
Number of ReturnsSingle and Multi-turnSingle Turn Only
Connection typeParallel Connection to Voltage SourceSerialLy Connected with Load
Quantity ControlledControls voltageControls the current
Conical TypeLinear and LogarithmicLinear Only

Then poxiometers, trimers and reosta are electromechanical devices designed to easily change resistance values.They can be designed as single-turn containers, presets, slider containers, or multi-turn trimmers.Wirewound reostalar are mainly used to control an electric current.Ponsiometers and reosta are also available as multigroup devices and can be classified as linear conical or logarithmic conical.

In both cases, ponciometers can provide highly precise detection and measurement for linear or rotary motion, as the output voltages are proportional to the bar position.The advantages of pontiometers include low cost, simple operation, numerous shapes, sizes and designs, and can be used in a wide range of different applications.

However, its disadvantages as mechanical devices include the eventual wear of the sliding contact bar and/or rail, limited current processing capabilities (as opposed to reostas), electrical power restrictions, and rotation angles limited to less than 270 degrees for uniform bodies.