Mike, your totally missing it. The throttling is taken care of. It worked fine before I started this discussion. This discussion is not about the throttling and ramping. Lets step back
There are two voltage sources going to sound module. The first one is the power supply. The second one is the track voltage for throttling.
Forget about track voltage. This is the confusion, I never was talking about that. The ONLY thing this discussion pertains to, is the power supply to feed power to the sound module.
In turning on the sound module, one hears a pop on the speaker, and all of a sudden you hear this train engine running. Well thats not realistic. This discussion is about taking the power source that goes to sound module, and instead of turning it on suddenly, it feeds it slowly, from 0 to 12v, over a period of about 6 seconds. This makes it sound like the generator is winding up from a dead stop.
That was the other confusing part. When I said "engine start", I wasnt referring to engine moving forward. I was referring to engine starting up first thing in the morning. The pistons are stopped. The pumps are off. Then we start the engine as you hear them start on Youtube. But as you prob read, I already got this using a TIP31C.