ORIGINAL: Tankhobby
I'm working on one that will count the number of hits (selectable from 1 to 9) then activate a relay, it will also have two additional relays, one for sound and one for another device, maybe a smoke unit like you have? With the extra relays and other devices it would need a larger power source, the 9 volt battery would not be sufficient. I guess it should detect the Tamiya signal to be more selective also?
I powered everything using a standard heng long 7.2V 2000 mAh battery pack. The sound card (the same used in Darkith's DBC) was powered by the same source, but with a 5v regulator circuit in between.
The ideas you have are interesting, especially the hits counter. The double relays system is a great addition. Why not offering the chance of a standard tamiya connector to power the board? Like many others, I have plenty of useless 1700 mAh NiCd and 2000 mAh NiMh power packs from my heng longs (every battery pack has been replaced with a 4A+ one).
About the tamiya signal, I dont' think it would be a plus for everyone. Maybe as an option, but that would make the board useless for Vstank, torro and heng long owners.