Tools you might need next
Decode resistor color bands to resistance value in ohms or find the correct color bands for a target resistance and tolerance.
Calculate current-limiting resistor value and wattage for LED circuits from supply voltage, forward voltage, and desired current.
Calculate output voltage and resistor values for voltage divider circuits from input voltage, R1, R2, and load considerations.
One tau is R × C seconds. After one tau a charging cap reaches ~63.2% of final voltage.
τ = R × CVoltage rises asymptotically toward the supply.
V(t) = V_final × (1 − e^(−t/τ))Discharging through R decays toward zero with the same tau.
V(t) = V_0 × e^(−t/τ)Updated: July 2026
Size RC on a reset pin so voltage stays low long enough for MCU startup.
Find when a Schmitt input crosses threshold after button release.
Estimate how many tau are needed to reach 99% of a step input.
Charging is exponential. Plan for multiple tau to reach near-final voltage.
Convert all C to farads and R to ohms before multiplying.
Predict how fast a capacitor charges or discharges. Enter resistance, capacitance, and supply voltage to get time constant tau and voltage at any time.