I'm in the process of converting my MTH Amtrak gallery cars to all-Metra CTA fluted cars. As part of the process, I'll be removing the external side-mounted lamps at the cab cars and drilling and installing new LED's to represent the pair of red markers (mounted high) and the pair of ditch lights (mounted low).
In prototype operation on the Pullman cars, the following lights are used:
- Three lamps centered near the top. All amber / white, with two across and one beneath with the lowest one being a 'mars' type light. Used when running in push (backwards) as headlights
- Two lamps halfway down below the cab windows, red marker lights used when train is running forward (tail lights)
- Two lamps at ditch location, amber, flashing alternate when running in push mode in conjunction with headlights.
I already bought off the auction site a pair of dirt cheap "railroad crossing signal" LED alternating flasher controllers with variable speed to use for the ditch lights. Unlike MTH PS2 or Lionel TMCC, I don't think I'm going to tie it to a DC bias or horn...I'm cool with them just alternating flashing as long as they're on. I'll probably dim them a bit.
I'll be drilling new holes for those, as well as for the red marker lights. And I'll be swapping out the incandescent side lamps on the existing body for new white LED's at the top cluster. I don't think I'm going to try to simulate a Mars light like the prototype, so I'll just make it a dimmer amber.
But this brings me to my question: Is there a circuit or mechanism that exists that can somehow automatically sense vehicle rolling direction (by way of some sort of small tach or optical reader or tiny mechanical encoder that interfaces with one of the wheelsets or something else?) and simply acts as a SPDT switch to activate either the markers or the headlights / ditch lights based on direction the car is rolling?
My current plan is just to include a small selector switch and just manually switch back and forth (probably mounted in the vestibule door for easy access without taking the car off track), but would be fun to have it happen automatically.
