Potentiometer Volume Knob

Application

This circuit uses the Potentiometer as an audio-style volume control. A 1 kHz sine wave drives the high side of the resistive element, the low side is grounded, and the wiper feeds a high-impedance load.

Design Context

A potentiometer is commonly used as a variable voltage divider for input level controls. Here RV1 is 10 kOhm and RLOAD is 100 kOhm, so the load is light enough that the wiper voltage closely follows the selected tap point. The Vin and Vout probes let the input sine wave and attenuated output sine wave be compared directly on the chart.

Expected Behavior

With RV1 at mid position, Vout should be a smaller sine wave with the same frequency as Vin. Moving the wiper toward the grounded end reduces the output amplitude; moving it toward the driven end increases the output amplitude. A heavier load resistor will pull the wiper voltage lower and show why real volume controls are usually followed by a high-impedance input.

Key Values

• Input: 1 V amplitude, 1 kHz sine wave
• Potentiometer: 10 kOhm
• Starting wiper position: 50%
• Load: 100 kOhm
• Simulation mode: transient

Suggested Experiments

• Change the wiper position and compare the Vin and Vout amplitudes.
• Reduce RLOAD to 10 kOhm and observe the loading error at the wiper.
• Change the sine-wave amplitude or frequency and confirm the potentiometer scales the signal level without changing the waveform shape.

Featured Component

The Potentiometer is a three-terminal linear variable resistor. In this circuit it acts as an adjustable divider, turning the wiper into a controllable fraction of the input signal.