what is a potentiometer
potentiometers are widely used in the field of the electronics. Potentiometer is a variable resistance which has three terminals- two terminals are connected to the ends of the resistor and third terminal acts as a slider or wiper on the resistance acts as a variable resistance which is used to control the flow of the electric current. three terminal of the potentiometer marked in the following – two terminals of the potentiometer marked as blue or green and the third terminal which is connected to the slider is of the black colour.
potentiometer is a tranducer that is used to measure displacement, emf (Electro Motive Force) of the given cell, force and pressure. it is a passive transducer.it consist of resistive material whose resistance is proportional to its length. a fixed voltage applied across the coil using an external voltage supply. the output signal is the D.C voltage between the movable contact on the terminal of the coil. slider displacement is proportional to the output voltage.
As we know that when we increase the flow of the current the value of the potential difference or voltage is decreased due to the ohms law
We can increase or decrease the value of the electric current manually with the help of the potentiometer by a moving handle or contact. We can also called potentiometer as a pot. Potentiometer is used to control the volume of the radio and also used for the speed control of the small motor in the automation sector and also found in the controlling of the volume speed and the brightness of the lights etc.
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construction of the potentiometer
Every potentiometer consist of following parts:-
- Resistive element
Pins- Pins are the metallic contact where we connect the wires. Potentiometer has three terminals two of them are fixed and one variable. Here in the figure above three pins are shown as 1, 2 and 3. here pin 1 is the power input pin 2 is the signal and the pin 3 is the output.
Resistive element – Resistive elements of the potentiometer is the main parts of the potentiometer. Resistive element is connected between the both fixed resistor as shown in the figure above. The quality of the resistive element depends upon the performance of the potentiometer. It is made up of different materials like wire wound, carbon resistors and sometimes graphite also used for great performance. the wire used for making the resistance of the potentiometer is manganin and constantan. they are alloys and posseses high resistance and high temprature coefficient
Shaft- shaft is the moving contact on which wiper is mounted. Shaft is used for calibaration and increase and reduce the speed etc.
Wiper- wiper is the third terminal of the pot and slides over the resistive strips to make electrical contact. The resistive elements may be flat or angled in shape. It is mounted over the shaft and when we move the shafts wiper slides over the resistance.
what are the types of pot
Here we have differentiate the pots according to the moment of the pot slider and they are of two types:-
- translational type
- rotational type
Translational type pot
in this type of pot, motion of sliding contact is linear.figure shows the translational type pot
V0 = Vi * R’ / R
V0 = input voltage * [resistance at output terminal CB] / Resistance at input terminal AB
Rotational type pot
here you can guess as the name suggest, the motion of this type of pot is rotary or rotation in circular direction. in this type, motion of the wiper is rotary for the measurement of the angular dispacement and are cicular in shape. figure given below that help you to understand about rotational type pot :-
The displacement may be a full scale angular displacement or as small upto 0 degree.
working of the potentiometer
pots are used as a voltage dividers that means it divides the voltage of large voltage into the smaller voltage with the help of the sliding contact on the resistors.
whenever we move the shaft of the pot the wiper that is attached on the shaft moves on the conductive plastic or resistive element and increase and decrease the voltage as per requirement.
Johann Christian Poggendorff has discovered the pot
this video also helps you in better understand that how a pot works