Vol. IV — Electronics · Tool
A resistor and a capacitor set how fast a voltage rises or falls. Change R and C — τ updates as you type, with the familiar 63%, 95%, and 99% marks.
τ (tau) is the product of resistance and capacitance: τ = R × C. After one time constant, a charging capacitor reaches about 63% of the final voltage; after three, about 95%; after five, about 99%. Discharge follows the same marks toward zero.
Bigger R or C stretches the curve. Timing circuits, soft-start filters, and debounce networks all start from this product. The secondary figure 1 / (2πRC) is the cutoff of a simple RC filter — open the full RC filter tool for low-pass / high-pass gain and phase.
Pick parts on Resistor codes, combine resistances on Series & parallel, or revisit loops in the Circuit explorer.