I use an Eheim dual compartment feeder. It's in daily use so not much change to the critters' routine when I'm not around, except the evening treat of frozen stuff which I thaw and feed manually.
It's a bit of a beast but works well and even retains settings after changing batteries. I think the only thing I need to do is set the clock after a battery change. I MacGyvered a mounting rig out of scrap acrylic for it that includes a section which extends below the waterline. That's my 'feeding ring' solution. Pics follow:
