Rheostat Configuration

Introduction

Potentiometers, also known as pots, are useful electrical components that allow a person or a machine to directly tune the voltage or resistance in one part of a circuit. In its normal configuration, a potentiometer acts as a variable voltage divider. If a voltage source is connected between the two pins, called terminals, the voltage over the third pin, known as the wiper, will vary with the position of the potentiometer shaft. This shaft can, for example, be controlled by a slider or a thumbwheel.

Model

In this example model, a thumbwheel potentiometer has been connected in a rheostat configuration, working as a variable resistor. The terminal pin connected to the ground has been short-circuited with the wiper pin. This means that the voltage over the terminal to the wiper will be the same as over the two terminals. When no other components are connected in a series, the voltage will be same as the input voltage.

The current flowing from the input terminal to the wiper will, however, depend on the angle of the thumbwheel, hence its use as a variable resistor.

Simulation

To simulate the model, perform this step:

• Click the Simulate button in the top toolbar .

Plot the results

Explore how the current through the rheostat decreases as the potentiometer gets turned around. Plot the stored plot called PotentiometerCurrents by double-clicking it from the Stored Plots section.

You should now see the following graph:

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