Here we’ve taken the VERY SIMPLE THROTTLE design and added a tethered walkaround cab. This adds a great deal more flexibility and user-friendliness to the beast, but please note that one should not unplug the cab when power is on, as it will result in the train taking off at full speed and the directional relay disengaging (neither of which is a good thing). If your layout is relatively small, and you can walk easily from end to end using a coiled phone cord of appropriate length, then this will probably be just what you need. If, however, your layout is of such a size or configuration that you really need several places to plug in the throttle, then you should consider the “semi-tethered” implementation shown farther down this page.
Now, adding a STOP/RUN toggle switch to each cab plug-in location gives us the ability to move the walkaround cab about the layout. Just remember to flip any toggle to its opposite location before unplugging, the flip any toggle again once the cab has been reconnected in a new location. You can implement any many (or as few) plug-in locations as you desire. Note that there is no fixed STOP or RUN position for each toggle switch; like a 3- or 4-way light switch in your home, you simply flip any toggle to the opposite position to move from RUN to STOP…or from STOP to RUN.
If you’d like a slightly more “elaborate” cab, shown below is a version with a “RANGE” selector toggle. In particular, if you have Z-scale or Marklin locos, you’ll want this cab, as it limits the maximum voltage on the track to approx. 10 or 8 volts, respectively.