If you can fully develop a system through this that works as an emerald farm without killing the villager, mind letting me know the specifics on the timing and other other issues that may arise? I'd be interesting in seeing how you pull it off.
Ended up using Computercraft for the timer.
edit startup with this timer, this assumes the attractor is on the left:
Code:
while true do
rs.setOutput("left",true)
os.sleep(40)
rs.setOutput("left",false)
os.sleep(12)
end
My first expedition into the realms of CC so it can probably be improved, but don't mess with the timing, this shaves it darned close. If you want to feel safer increase the first sleep and decrease the second. I put a piece of redstone pointing at a block below the attractor although the redstone is probably not necessary. I did this below the attractor because I worried that a direct signal might deactivate the ritual.
I lost a few villagers in testing because CC seemed to be taking naps and not rebooting properly, hit the reboot command and it seemed to skip the first line so it was sleep 40 turn off sleep12 then turn on. ah well, to fix just have an override lever attached to the block beneath the attractor.
you could probably use this timer for any meltable entity you wanted to farm like iron golems for iron. Heck, throw in a witch(in another smeltery without fancy timers and such) and you've got a pigiron farm.
EDIT: Attempts at pictures:
Full view
Underneath
