Arfa Daily was thinking very hard :
... who can't remember all the formulas and how to read resistors with 6
bands, and need to know the forward voltages of LEDs and can never remember
the connections to an LM317, or the formula to calculate the resistor values,
or the configuration of an RC tone stack filter and and and ...

RS Toolkit. New app for iPad and iPhone. Free, and very good !

Not sure if it will be on any iTunes Stores outside the UK, but worth a look

Arfa

It is a pity it is only useful to LESS than half the population.
It does not seem to be available to the majority who use Android
phones.

--
John G