Fair point with the neoprene, ive seen a few people with patches over though so gawd knows what theyve done to it. A few in our club have mentioned the seams going but membrane can have that problem too.
Anyway, the interface...
The PDF document with circuit diagram, components, test details along with plans for making the custom connector is here:
http://www.geocities.com/scubadiver_...load/cvmif.pdf
There is a PCB layout on there but as i dont have etching materials i used stripboard. I found a great single page PDF plan which fits onto 14 x 7 holes so the size is 3.5cm by 2cm.
There is no web address on the PDF, my history and google are unable to find it again but if you want the file, pass your email address and i can attach it.
The only other construction note is the transistors are TO-92 case style so looking directly at the flat face, from left to right, its Collector, Base, Emitter.
I havent yet made a custom plug, will have to do some cutting for that however ive got mine working using the low tech method of 2 x PCB pins and some bluetac.
I got all the components via Maplin mail order (as they shop had nothing i wanted)
Another vyper page with lots of interface designs is here:
http://vyper.bunny.hu/e_index.html