This simulator opens a condenser microphone capsule: a thin conductive diaphragm, a perforated fixed backplate, an insulating spacer and housing, a polarization supply behind a large resistor, and a high-impedance buffer. Change the tone, acoustic pressure, air gap, bias voltage and compliance and watch diaphragm motion become capacitance change and output voltage.
• A 3D magnified condenser capsule with a conductive diaphragm, a perforated fixed backplate, an insulating spacer and housing, a polarization supply with a high resistance, and a high-impedance buffer. • Controls for tone frequency, peak acoustic pressure, nominal air gap, polarization voltage and diaphragm static compliance. • Six readouts: instantaneous pressure, diaphragm displacement, capsule capacitance, AC buffer input, displacement amplitude and voltage sensitivity. • Curves & measurements, two guided experiments with a verification bench, and Learn & assess lessons and a quiz.
The diaphragm responds as a damped mass-spring: with r = f/2000 and a mechanical resonance at 2 kHz, the amplitude is X = ppeak · compliance / √[(1 − r²)² + (0.4r)²]. The gap shrinks and grows, so capacitance is C = ε0 A / (d − x). Because the resistor is huge, the charge stays constant at Q = C0 Vbias, and the output is ΔV = Q/C − Vbias.
Sensitivity therefore scales with bias voltage and falls with a wider gap. Also, a diaphragm moving toward the backplate raises C and lowers V, which is why the constant-charge voltage is opposite in sign to the capacitance change.
The diaphragm is a uniform piston of 1 cm² with damping ratio 0.2, and the sensing is ideal constant-charge. There is no electrostatic spring softening, pull-in, hole detail, noise or preamp loading. Time is slowed 100 times and displacement is enlarged 2 million times so it can be seen. It explains the principle of a capacitor microphone, not a specific commercial capsule.
Sound pressure moves a thin diaphragm relative to a fixed backplate. That changes the gap and therefore the capacitance. With a nearly constant charge on the plates, the changing capacitance produces a changing voltage.
The stored charge is Q = C0 Vbias, and the output swing scales with that charge. In the model, moving from 20 V to 100 V makes sensitivity five times larger with unchanged mechanics.
It lowers the baseline capacitance and reduces voltage sensitivity. The Wider air gap experiment shows both falling together.
No. It uses a uniform piston diaphragm with a 2 kHz resonance and ideal constant-charge sensing, and ignores noise, pull-in and buffer loading. It is a principle demonstration.