Just using an ATTiny. coding is dead simple for strobe/beacon.
Got the issue sorted out as it was "flashing off" not "on"
http://www.rccanada.ca/rccforum/showthread.php?t=411018
It is back to this flashing pattern with AVR run from 5V and lights from 6.6 versus the bad flashing pattern when trying to run it without the extra circuitry.
https://www.youtube.com/watch?v=uBVoxlwcNJI