Thanks for bringing my attention to this thread.

Looks easy. Let me have a look. I can send you my updates by email.

I have a few suggestions:

• Use a bit darker colours for resitor colour bands. The current colours are a bit too bright and vivid. Plus, to my old eyes, orange is difficult to distingush from yellow. Same for white and silver.
• Use units in brackets, e.g. Voltage (V), Current (A), Resistance (Ω), Power (W).
• It took me a while to figure out that in Ohm's Law and Power calculations, one line edit was for results and not for the input. I think it should be made obvious immediately. Either use a label for the output instead of line edit or rearrange the tabs somehow. I have not yet worked out how.
• Make sure the edit boxes accept digits by default and do not accept letters. The easiest way would be to use double spin boxes. That would also make it easy to cater for the divide-by-zero checks: if the denominator is zero, the "calculate" button could be disabled.

Actually, the whole thing can be implemented in a simple JavaScript. Let me dig out my HTML course material