Electronics calculators
Ohm's law, dividers, filters and the sums you do before you reach for the soldering iron.
Ohm's Law CalculatorGive any two of voltage, current, resistance or power — get the other two.Resistor Colour Code CalculatorRead a resistor from its bands, in 4, 5 or 6-band form.Voltage Divider CalculatorOutput voltage, current and power for a two-resistor divider.LED Resistor CalculatorThe series resistor an LED needs, with the nearest standard value.Series & Parallel Resistance CalculatorTotal resistance of any number of resistors, in series or parallel.RC Filter & Time Constant CalculatorCutoff frequency, time constant and rise time for an RC pair.Voltage Drop CalculatorVoltage lost in a copper run, and whether the gauge is adequate.Battery Life CalculatorHow long a battery lasts at a given load, with a realistic derating.Wire Size CalculatorThe smallest wire that carries the current and stays inside the voltage drop limit.Three-Phase Power CalculatorkW, kVA, kVAR and line current, with the √3 in the right place.Transformer CalculatorTurns ratio, winding currents and core size from the voltages and rating.555 Timer CalculatorFrequency, duty cycle and pulse width for astable and monostable 555 circuits.PCB Trace Width CalculatorTrace width for a given current and temperature rise, to IPC-2221.LC Resonance & Reactance CalculatorResonant frequency, reactance, impedance and Q for an LC circuit.Power Factor Correction CalculatorThe capacitor bank needed to raise power factor, and what it saves.Op-Amp Gain CalculatorGain, output voltage and bandwidth for the standard op-amp configurations.Decibel CalculatorConvert between dB, dBm, watts and voltage ratios — with the factor of 10 or 20.