ElectroCalc is a fast calculator for electrical and electronic projects. The PRO version of ElectroCalc doesn't have any ads and contributes to the developer. Available calculations: Basic. Ohm's Law. Resistor - Color Code. Equivalent Resistance. Voltage Divider. Electronics. Timer 555 - Monostable. Timer 555 - Astable. Zener Diode - Voltage Source. LM317 - Voltage Source.