Tom -- thanks. Indeed, the 30B does put out 18VAC - I just checked mine and at the terminals, it's 18.4 variable to base and 19 VAC fixed to base. That may not be what the engine sees on the track, of course (especially since I haven't cleaned the track in a while). My electrocoupler button on the iPhone app has not been grayed out the last couple of times I've run the engine. The opening of the coupler seems to be a bit sporadic - it doesn't always open even though the engine goes through the 'sound cycle'. I haven't looked at it very carefully yet to see if its triggering but just not opening far enough or something else.
Without taking the shell off the tender, there does appear to be an LED in the backup light (or maybe what I'm seeing is just the lens). So what is in the tender - presumably the speaker and the electrocoupler - so that accounts for the four conductors?? I'd be interested in Carl T's solution -- I'll take a look at his website. Is there a backup light output on the control board for the non-Polar Express Berks? Does anyone have a circuit diagram for that board?
What I've found impressive so far about using the LionChief app on my iPhone is the slow speed control - you can make the engine really crawl. I also like the fact that you can 'tune' the whistle sound - I set it a bit lower than the mid-point, giving it a 'throatier' sound to my ears. I'm going to be very tempted to buy another Bluetooth-enabled engine (maybe a geep?) - the LionChief is a nice and pretty intuitive control system (I did cheat and watch a Youtube video about the controller before the engine arrived).
