Hi
I have made a piece of software that can do all sorts of electronic calculations. The software is free.
Some highlights:
Convert between color codes and numeric values for many types of components.
Analyze or design an air core inductor
Color/wavelength of leds and design of circuits to drive leds from DC or AC
Timing and curves, usefull when programming software uart's and IR rx/tx.
Calculate crc, checksum and modulus for datablocks, can also analyze a datablock for what checksum/crc was used
Analyze and design power supplies with 78xx and LM317 style regulators
Calculates Fo for RC, RL, RLC circuits
Calculates for PT100, NTC and all types of thermocouples
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The software is here:
Th site includes screen shoots and descriptions of many of the functions.