Engineering Equation & Reference
Size base resistor Rb with proper saturation overdrive margin for driving relays, motors, and high-power LEDs from 3.3V/5V GPIO pins.
Electronics Calculators
NPN BJT Switch Base Resistor Saturation Calculator (GPIO Driver)
Size base resistor Rb with proper saturation overdrive margin for driving relays, motors, and high-power LEDs from 3.3V/5V GPIO pins.
Related Engineering Calculators
Electronics Calculators
4-Band & 5-Band Resistor Color Code Calculator (Visual EIA Chart)
Interactive visual 4-band and 5-band resistor color decoder showing live painted resistor bands, exact resistance, and min/max tolerance range.
R_4band = (10·D₁ + D₂) × Multiplier ± Tolerance%
Launch Interactive Lab →
Electronics Calculators
LED Series Current-Limiting Resistor & Wattage Calculator (with E12)
Calculate exact and nearest standard E12 current-limiting resistor values and power ratings for single or series LED strings.
R = (Vs − N × Vf) / I_LED, P_R = (Vs − N × Vf) × I_LED
Launch Interactive Lab →
Electronics Calculators
Ohm's Law & Joule Electrical Power Calculator (V, I, R, P)
Instantaneous solver for electric current, power dissipation in watts, conductance in siemens, and hourly energy consumption.
I = V / R, P = V × I = I²R = V² / R
Launch Interactive Lab →
Electronics Calculators
Resistive Voltage Divider & Thevenin Impedance Calculator
Compute divided output voltage Vout, decibel attenuation, bleeder current, and Thevenin equivalent output resistance Rth.
Vout = Vin × R₂ / (R₁ + R₂), Rth = (R₁ × R₂) / (R₁ + R₂)
Launch Interactive Lab →
Electronics Calculators
Parallel & Series Equivalent Resistor Network Calculator
Compute exact parallel and series equivalent resistance for two or three resistor combinations simultaneously.
1 / R_parallel = 1/R₁ + 1/R₂ + 1/R₃, R_series = R₁ + R₂ + R₃
Launch Interactive Lab →
Electronics Calculators
Capacitors in Series & Parallel Calculator (+ Charge & Energy)
Calculate total capacitance for parallel banks and series strings along with stored coulombs Q and electrostatic energy.
C_parallel = C₁ + C₂, C_series = (C₁ × C₂) / (C₁ + C₂)
Launch Interactive Lab →