[wireless_john]

Spent a fair bit of time working on this! The attached PDF is my latest attempt at replacing the 5P4W switch with a SP4W switch and some logic. Haven't double checked it, but I think it's right. The page is divided in to rows, each row representing one pole.

After many attempts I've got it down to five ICs (from seven) which fits well with the five columns of ICs on Karens logic PCB. One on the end of each column. Losing another IC will be the focus of any more attempts to simplify it, rather than just saving a gate. Saving one AND gate or the three input OR gate would be good! That will save a whole IC.

Anyway, I'm not a professional logic designer but I recognise that some switch positions will leave floating inputs. I think the answer here is pull-down resistors but not too sure what values. 10k? Is that right?

Any comments/advice from the experts welcome.

Thanks.