I think the second run of the L2as had the 4 chuffs and puffing SSMU (maybe?) smoker. The 4 chuffed 0-8-0 I mentioned had a constant stream smoker.
Not sure the DPDT would work right as the RS4 board looks for a rising edge trigger. That's how all these simple chuff triggers (microswitch/cam, magnet/reed, magnet/Hall Effect, etc.) work so well. When making a cam you only have to consider the edges being rounded for a physically non-bouncy switch actuation and not an electrical pulse width/duty cycle consideration. I went with a 1mm radius edge to keep from slapping the switch around too much. This was just a guess really.
I did try to get a little cheeky and actually printed some experimental chuff lobes to epoxy onto the original 2 lobe cam. It actually worked but it was kind of a pain to get the lobes placed just right to get square sounds.
