Toilett processing (Was: ZX-TEAM meeting and Webcam)

You read my mind... I was going to suggest a spring arm pressing against the roll. The further the arm travels, the lower the roll. This should also take very little adjustment since you are looking for % left. Actually, since rolls all share a common spindle diameter... it would be easy to have this auto adjust for good thick rolls vs, cheap economy paper. You know the end location, so add a sensor to know when the roll has been changed. When the "new roll" sensor is tripped, take the current reading, that is max size. Now you can calculate the difference from there to empty, and relay a % left no matter what the initial thickness is. (the only time this would start to be off is on roll "reloads" of partially used rolls) Two problems with the earlier mentioned rotation counter... 1: you need to deal with vastly different sheet counts (Scott will turn WAY more times than Charmin will, but both are roughly the same diameter, just Charmin is thicker so has fewer sheets per roll, thus fewer turns till empty). And of course, a turn based counter needs to subtract for roll re-rolling... for the times the cat decides to use it as a batting toy, and unrolls half of it onto the floor. The counter has to subtract turns as you spin the paper back onto the roll. Oh yeah... and a spin counter would be throw off by those 4am "where did the end of the roll go blind half asleep multiple rotations trying to find the start" situations. Nah... a simple spring arm reading resistance based off roll diameter would probably work best. -chris <http://www.mythtech.net>