calc.engineer / PCB & Electronics / Capacitor Charge

Capacitor Charge v1.0.0

Calculates RC capacitor charge timing, energy storage, and transient voltages. Given resistance, capacitance, supply voltage, and optional initial voltage, computes the RC time constant (τ = R×C), time to reach standard charge thresholds (63%, 86%, 95%, 99%), voltage at key time points, energy stored (E = ½CV²), and peak charging current. Optionally calculates time to reach a specific target voltage using t = -τ × ln((Vsupply - Vtarget) / (Vsupply - Vinitial)). Essential for timing circuits, power-on reset delays, debounce networks, and soft-start designs. Chain from rc_filter for frequency-domain analysis or timer_555 for oscillator timing.

← from rc_filter← from ohms_law← from resistor_color_codefeeds timer_555 →feeds ohms_law →
Series resistance in ohms (R). Controls charge/discharge rate.
Capacitance in farads (C). Use scientific notation, e.g. 1e-6 for 1 µF.
Supply voltage in volts. The voltage the capacitor charges toward.
Initial capacitor voltage in volts (default 0 for fully discharged).
Target voltage to reach in volts (optional). When provided, calculates time to reach this voltage. Must be between v_initial and v_supply.
Fill in the inputs and Compute to see the structured result.

From an agent (MCP) or the API

curl -X POST https://calc.engineer/api/capacitor_charge \
  -H "Content-Type: application/json" \
  -d '{"resistance_ohm": …, "capacitance_f": …, "v_supply": …}'

MCP: connect to https://calc.engineer/mcp and call capacitor_charge.

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