What is a Potentiometer?
Potentiometer is a small sized electronic component whose resistance can be adjusted manually. Increasing or decreasing the value of resistance controls the amount of current flowing in a circuit. The potentiometer is used in various electronics, for example: is used as volume knob in music systems, as fan regulators etc. Potentiometer has two strips made on it resistive and conductive. Resistive strip is made of carbon and is responsible for potentiometer’s resistance variance feature. Conductive strip helps the potentiometer to carry the current into the circuit in accordance with the resistance. To understand the theory of our humble potentiometers (or pots), let us know the parts of the potentiometer:
Fig. 1: Image showing Terminals of a Potentiometer
Fig. 2: Symbol of a Potentiometer
The only catch here is that using the above circuit in place of a log pot will reduce the input resistance that the source voltage will see. So some amount of experimentation should be done to choose the value of y. Similarly, reverse log pots can be emulated using linear pot by simply putting R3 resistance across R1 and taking the output voltage across R2.
These are also potentiometers but are “set and forget” devices which are directly mounted on to PCB or bread board to fine tune the circuit. For example, you want to bias a transistor to an exact potential which in turn relies on resistance, you can use a trim pot to get the exact voltage (by changing the resistance) and then forget about it. One might have to use a screwdriver to change the resistance which might not be very convenient but this way it is difficult to change the resistance once you have set it to the desired resistance.
Fig. 9: Typical Image of Potentiometer
Filed Under: Tutorials