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Resistor Calculators
Resistor color code decoder, SMD code calculator, LED resistor sizing, RC time constants, and inductance.
Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes to find resistance value and tolerance. Supports all standard color bands.
SMD Resistor Code Calculator
Convert SMD resistor marking codes to resistance values. Supports 3-digit, 4-digit EIA, and R-notation formats.
LED Resistor Calculator
Calculate the required current-limiting resistor for an LED. Enter supply voltage, LED forward voltage, and desired forward current.
RC Time Constant Calculator
Calculate RC time constant (Ï„=RC) and capacitor charge/discharge times. Essential for filter and timer circuit design.
Inductor & Reactance Calculator
Calculate inductive reactance (XL = 2Ï€fL), LC resonant frequency, and time constants for inductor circuits.