Ok so before I saw these replies, I tried reversing the position of the bridge, so now the armature is wired directly to the rollers through the bridge (so armature polarity is constant) and the PS1 motor output leads go to the field, so I can regulate field DC voltage and polarity using the throttle, and armature DC voltage is always based on rectified track voltage.
And... So far so good! Motor runs MUCH cooler, and all PS1 functions work great! Starting and accelerating is almost as smooth the can motors in my real PS1 engines.
So now, given the above responses, (thanks guys for the tips) am I over-powering the armature by having *it* go right to the bridge? I wouldn't think so, since the armatures pull non-rectified AC current right from the track. What's the relationship of AC voltage to DC through a FWBR? Just don't want to damage the motor, but I'm going on about 20 minutes constant running at 11 volts from the transformer (which is pretty fast) with no performance issues! I suppose if the rectified DC voltage can get too high, I can just be sure to limit throttle to something less than what the KW outputs.
Also, I measured the running current pulling the train seen in the video. With the two incandescent bulbs in the engine, two bulbs at the track (one at a switch and one at a lockon location) I'm pulling like 5.2 amps (with some spikes at around 6 when I start and accelerate). Seems like a lot for only 11-12 volts, so maybe I need to limit it there.
