Foundation of Radio & Electromagnetic Science
Crystal Set Coil Winder
Calculate exact copper wire turns and inductance for DIY crystal radios.
Resistor Color Code Decoder
Decode 4-band and 5-band resistor values instantly. Visual interface based on the 1920s RMA color standard.
LED Resistor Calculator
Calculate the perfect series resistor to protect your LEDs. Prevent burnout and extend battery life with precise Ohm's Law calculations.
Ohm's Law Triangle
Calculate Voltage, Current, and Resistance using our interactive triangle. The fundamental tool for electronics DIY.
Battery Life Calculator
Estimate run time for electronics based on battery capacity, load, and realistic efficiency factors.