Sorry for the silence. I was away from my computer all day yesterday.
I'm working on what I hope is a final schematic. Will the flash unit spend more time asleep or awake? We can design the circuit so that the relay is off most of the time, saving power.
Thanks, and I will play with these, and let you know what I find. The more I read and learned about these circuits, the more I kept thinking that it could be done without the relay also, but I hadn't really learned enough to figure it all the way out myself.