Can you replace a Resistor with a Potentiometer?

A resistor – or more correctly, a fixed resistor – is a passive component, which impedes the flow of current through an electrical circuit. A resistor is measured in Ohms and comes in a wide variety of values – from zero Ohms to several Mega Ohms. The size of the resistor varies depending on the heat it has to dissipate while current passes through it. The heat in turn is dependent on the power handled by the resistor. Therefore, a resistor is categorized into different Wattage types. On the lower side, the Wattage may go down to a sixteenth of a Watt, and on the higher side, kilowatt sizes are quite common.

Resistors come in various flavours. They may be ceramic, carbon, light-dependent, wire-wound, metal film, surface mount, high-power and many others.
Many times, in place of fixed resistors, variable resistors have to be used. Variable resistors, potentiometers or ‘pots’, as they are called, are used when the volume of the stereo has to be changed, the light has to be dimmed or an ocean-liner has to be repositioned. In a potentiometer, the central pin is connected to a wiper. A spindle rotates the wiper, which makes contact with the resistant material inside. Consequently, the resistance between the central pin and the outer pins varies as the spindle is rotated.ramic, carbon, light-dependent, wire-wound, metal film, surface mount, high-power and many others.
Therefore, if the potentiometer is rated at 100 Ohms, by changing the position of the spindle, any resistance between 0 and 100 Ohms may be achieved. This suggests interesting food for thought – can a potentiometer replace a resistance in a circuit?

The answer is yes, provided three conditions are met:

1. The potentiometer must be able to assume the value of the resistor.
2. The power rating of the potentiometer must be same as or greater than that of the resistor.
3. There must be adequate space to accommodate the potentiometer.
The last criterion exists because, in general, a potentiometer is larger than the resistor it will be replacing. Of course, smaller-sized potentiometers are also available; some especially made to be used as preset potentiometers in circuits -


One word of caution when replacing a fixed resistor with a potentiometer: fixed resistor tolerances (variation in resistance value with temperature and age) are much more restrictive when compared to potentiometer tolerances. Typical tolerance values for fixed resistors are 1%, 5% and 10%, although 0.1% and 0.01% are common. On the other hand, potentiometer tolerances rarely go below 10%. Therefore, circuit functions may vary when you replace a low-tolerance fixed resistor with a potentiometer, and you must ensure the variations are not catastrophic...