ONLINE TOOLS FOR ELECTRONICS

Online 555 Calculator
This tool use to calculate any parameter of 555 timer IC.

Standard resistance values calculator
This is EIA standard resistance value calculator

Serie and Parallel resistor closest calculator
This is a tool which to be used to combine of two resistors in series or parallel to gives a match better than the closest standard value, for the E12(10%) and E24(5%) series 
  Single layer coil inductance calculator
The inductance calculator for Single layer air coil inductor
Multilayer Air coil inductance calculator
The inductance calculator for multilayer air coil inductor