RC circuit: charge time
τ = R×C: time to N% capacitor charge — timers, delays, filters
Parameters
τ (63.2%)
V(t) after 100 мс: 0.48 В
1.00 с
- To 90%
- 2.30 с
- To 99%
- 4.61 с
- 5τ (full)
- 5.00 с
Charge: V(t) = V₀(1−e^(−t/RC)). Practically full at 5τ. For a 1 s delay at C=100 µF you need R≈10 kΩ (τ=1 s → 63% per second).