Overview of the Potentiometers & Choosing Right Potentiometers

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A potentiometer (simply “pot” or “knob”) is a variable resistor, having a three-terminal mechanically operated rotary analog device. The potentiometers are the most elementary component in electronics and also electric circuits. This simple component can be located nearly almost everywhere from a simple LED circuit to a critical SMPS circuit.

A potentiometer has three (3) legs. One leg connected to a moving contact called a wiper and the other two terminals are attached to a fixed resistance track. Potentiometers are not polarized. So, it can attach either of the outers pins to 5V and the opposite to GND. However, the values you get out of the pot will change based on which pin is 5V and which is GND.

The Potentiometers are passive devices, meaning they do not require a power supply or extra wring circuitry in order to execute their primary linear or rotary position function utilized to determine the EMF (electromotive force) of an offered cell, the interior resistance of a cell.  Also, it is made to comparison the EMFs of different cells.

It can also utilize as a variable resistor in the majority of applications. These potentiometers are made to use in huge quantities in the manufacture of electronics devices that offers the possibility of correcting electronic circuits to make sure that the appropriate outputs are obtained. Although their most obvious use needs to be for volume controls on radios and also other electronic devices made use of for audio application. By differing the placement of the POT-knob, it can make volume controls, speed controls, angle sensors with a ton of other useful inputs for various projects.

Types of Potentiometers

Potentiometers are an analog device containing basically two main parts electrical and mechanical:

  • An electrical part that consists of a fixed or stationary resistivity element, track or wire coil which specifies the potentiometers resistive value, such as 1kΩ (1000 ohms), 10kΩ (10000 ohms), etc.
  • A mechanical part that permits a wiper or contact point to move along the whole length of the resistive track from one end to the other changing its resistive value as it moves.

There are several methods to fix the wiper across the resistive track either mechanically or electrically.

These are one of the most typical types of potentiometers, where the wiper relocates along a circular path. These potentiometers are primarily used to obtain a changeable voltage supply to a fraction of circuits.

Rotary Potentiometers

Rotating potentiometers vary their resistive value as a result of an angular movement generally offers less than 300 degrees of angular movement from minimum to maximum resistance. Turning a knob or dial affixed to the shaft creates the internal wiper to move around a rounded resistive element.

There are many sorts of Rotary Potentiometer such as single-turn pot, Multi-turn pot, Dual-gang pot, Concentric pot and Servo pot each type of rotary POT has its own purpose and applications

Linear Potentiometers

In these sorts of Potentiometers, the wiper moves along a direct path. Additionally, referred to as slide pot, slider, or fader. This potentiometer is similar to the rotary-type however in this potentiometer, the gliding contact simply rotated on the resistor linearly. The connection of the resistor’s two terminals is connected across the voltage source. The moving contact on the resistor can be moved using a path that is attached through the resistor.

The terminal of the resistor is linked toward the sliding which is connected to one surface of the circuit’s output & another terminal is connected to the other surface of the circuit’s output. This kind of potentiometer is mostly made to use to determine the voltage in a circuit. It is used to calculate the battery cell’s internal resistance and also used in the mixing systems of sound and music equalizer.

Digital Potentiometer

Digital potentiometers are also called digit POTs which are made to use to control analog signals using microcontrollers. These types of potentiometers give an output resistance that is variable depending on digital inputs. Sometimes, these are also called RDACs (resistive digital-to-analog converters).

This potentiometer makes use of digital protocols such as IC or else SPI Bus (Serial Peripheral Interface) for signaling. Most of these potentiometers make use of basically volatile memory so that they did not remember their place once they are powered down and their final place may be stored through the FPGA or microcontroller to which they are linked.

4 Steps to choose a potentiometer of your project

Resistance (R-ohms) & Power rating (P-Watts) are the two primary criteria for picking a potentiometer. The resistance value primarily decides how much resistance it gives to the current flow which is measured in power rating depends on how much current it allows to flow through it. Right here are the 4 main steps to pick an ideal potentiometer

  1. Pick the right package and dimension for your potentiometer: The package and size are needed to make sure the potentiometer suits your circuit and that you can reach it to adjust it. Datasheets will give insight into the physical dimensions. Examples – consist of a rotating, a dial, or a slide button.
  2. Select the correct series: A potentiometer does you no good if it covers a range of zero ohms to 100 ohms but you need it to operate up to 1000 ohms. Conversely, if you need to make adjustments of 10 ohms, you’ll discover a range of 1,000 ohms too coarse to readjust. A lot of potentiometers start at nearly zero ohms, so you’re concentrating your choice on the high end of its range.
  3. Inspect the power rating: Make sure your potentiometer is rated for your circuit’s current and voltage. If you get a seemingly perfect potentiometer for a bass guitar amplifier, ensure it can manage the power going through it.
  4. Select the proper tolerance: Like all resistors, real-world potentiometers will certainly vary from their design by a given tolerance. This is no big deal for a bass guitar amplifier, but it might matter if you’re controlling a more noise-free signal, such as a thermostat in your house.

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