@illinoiscentral posted:Have some experience with auto-transformers, Variacs. First thing, if you try to stop the Variac at 19V you are going to get less than ideal resolution. Second thing is, you are tying the white wire to the track. Not good. A Variac is not isolating. It is copper wire wrapped around an iron core with a moving slider tap. It has no second winding; this is how you keep size and cost down, and get more output power for the same amount of magnet steel.
A better choice would be to have a Variac followed by an isolating step down transformer. I would like to recommend a Lionel 180W brick, but I don't know how it operates at very low input AC voltages; as in, if it has an internal circuit needs say 5VDC, at some point that circuit is not going to work. UL has limits on how much above and below 120Vac something has to work AND be safe, can't remember if its 10% or 6%, NAFTA or European union.
Another problem with Variac directly to track is if the plug was put on backwards somehow, you would have 120Vac (black wire) directly to the track. Very much not good.
If you go with an off-the-shelf isolation step down transformer, you will need fuses and/or circuit breakers.
You forgot to mention that since the neutral is tied to earth ground at the panel, without an isolating transformer, forget about running TMCC/Legacy, it won't work! My last word on the topic...
