Hey there,
Just sharing a handy tip for a somewhat unique situation. Our club has lots of tracks but sometimes they share transformers and run big MTH or other locomotives with lots of cars (that want at least 18-20V of track voltage). Of course the bump-n-go trolley basically derails itself at such high voltage (If you tried to run the trolley at 18V you'd find it's like a rocket!), so we can't run it on the siding tracks at the same time someone is running a big train...
I thought about a regulator, or putting a PWM circuit... but the trolley is super simple so the fix should also be super simple. I found it works well to Just open the trolley (4 screws) and slip a pair of wirewound resistors in series with the motor. $2.49 at radioshack [trolley resistor] for the set of two. There's lots of room inside the trolley. I tried many values, but two 50 ohm /10W in series (so 100 ohms total) works perfectly if you want to run the trolley in 18-20V range but not have it destroy itself (and surrounding layout).
It's super simple. Open the trolley, un-solder the yellow wires on top of the motor. Add the two resistors in series and solder. Close the trolley.
I ran this for 12 hours and the resistors don't even get hot because the motor is tiny and its current is small.
~Adrian
