Here’s another throttle design incorporating a pulse stream riding on a DC level. I’ve redrawn the basic design which originally appeared in the now-out-of-print book “34 New Electronic Projects for Model Railroaders” by Peter J. Thorne, making only a few minor changes. I have not yet tried this throttle, so I can’t comment on its operation; however, this is/was a very popular book and I suspect there are many copies of this throttle in use.
The Speed Control pot could be readily relocated to a tethered handheld unit, allowing you a bit of walking-around space. The Direction switch could be converted to a relay, with it’s control toggle also located in a handheld. See my design for the “VST w/ TWAC” for guidance on this addition.
If you have questions about this design, feel free to Email Me and I’ll try my best to help. If you build (of have built and used) this throttle, please let me know about your experiences with it.