Tunable RC Low-Pass Filter

Application

Use this circuit as an adjustable sensor filter or audio tone-control starting point.

Design Context

A resistor feeds the output node while the variable capacitor shunts high-frequency content to ground.

Expected Behavior

Larger capacitance lowers the cutoff frequency and increases high-frequency attenuation at Vout.

Key Values

• R1 is 10 k.
• CV1 ranges from 100 nF to 1 uF.
• The AC sweep runs from 10 Hz to 1 MHz.

Suggested Experiments

• Change CV1 position and rerun the sweep.
• Change R1 to shift cutoff frequency.
• Compare Vin and Vout at high frequency.

Featured Component

The variable capacitor component exposes a position setting and displays the computed capacitance.