@Coztick I hear the Rube Goldberg critique. That's fair when looking at the CVS at it existed. Yes, the current BC technology does work. Snicker and point if you like.
I'm the curious type. It could be fun and possibly there is some value in ditching or augmenting the BC. That's enough justification to me for having fun. You might play by using gear you bought to look at fish; I play by burning brain cells thinking about and building toys. To each his own.
@Luis H thanks for your eagle-eyes spotting 2psi in the patent. Understanding 4.5ft over-pressure was used before is a great design baseline.
I'm currently going to try an exhale and inhale direction vent, use a stiffer spring, and omit the equalizing air valve. I do have a power-inflator, so can equalize manually if needed. The If its behavior just doesn't work well, I might hack up a cheap second stage.
A clear tube for the pressure vessel (low differential still counts) should make it possible to actually see the air/water ratio and watch the valves operate. This first version will also be way oversized because it's cheaper and easier to cut the tube shorter than try to stretch it
Right now the projected system weight is 3lbs for the tube & endcaps & valves, plus 1.23lbs for the power-inflator with LP hose. The ScubaPro Litehawk travel BC lists at 5.28lb with straps and pockets and stuff, so currently we're in the same ballpark.
Also
@Luis H, thanks for the short history lesson about early BC adoption and fears!
danstrider