They are a sort of write only diagram. In other words while you can create them they are almost impossible to read except in the more trivial cases.
Agreed and noted.
When people said put a 1M resistor across the the piezos they meant across each individual one on the input side of the multiplexer.
You have lots of unterminated inputs to that chip and the cross talk will be bad.
I've attached an updated diagram. I though having the 1M resistor in paralell to the entire multiplexing process would be ok. Is it because I have to add am what I've read as a 'pull-down resistor' before each piezo that this will minimize the cross-talk? - Although I'm still finding it hard to understand why that would be as well.
Edit: Schematics for IMT ProjectC is more accurate.
