what you forget is that I am trying to make a drop in replacement for a unit made long before most of the users of this forum (including you and me) were even born and it's a totally different technology and I don't want to rock the boat too much, the unit I am currently trying to replicate had nothing to do with the ignition switch, I did do as you suggest with a previous prototype but have changed my design (from a pic one to a descrete one) and want to raise the stakes and get this one to do exactly as the original.
my main issue at the moment is that I do not know how may volts I will have on the dynamo when it first starts to turn and/or some power is supplied by the ignition lamp, it will probably be enough to run a low voltage reference perhaps even up to 3 V, the rest of the circuit will run off the battery, by using the dynamo to power the reference I will be making a way to keep the circuit off when the engine stops (because the ref will become 0 so the feed back voltage will be way higher and fool the "logic" keeping the mosfet off) and telling it to start up when the engine does.