Crossing transformer zones

Great to know! Thanks.

BR,
-Eino

This needs to be sketched out, to follow the sequences. I can think of sorta ‘auto-power’ by jumpering to next section with a Diode, to a Relay that enables that section, only if the polarity matches (or not powered). Repeat for next section.

As I start to build the wife’s DC layout, will need to work out a crossover and reversing loop, so she can run 1 or 2 trains and isolated sections from the Main for Switching.

Way Back when I was into HO I came up with a way to do this using 2 cheap 3 pole on/off/on switches. And 3 isolated sections of track in between the yard and mainline blocks. I had to stop the train then throw a switch but it prevented any shorts from happening. I use 3 isolated sections of track in A row each one slightly larger than my longest loco.
The 2 switches were mounted side by side. Then I drilled a small scrap of wood so it would slide down over both switch levers at the same time and glued it in place with hot glue. This insured both switches were always thrown the same way at the same time.


Yard was on Transformer "A" Main Line was on Transformer "B"

Yard, Iso-TK #1, Iso-TK #2, Iso-TK #3, Maim

Switch one pin 1 --Not used
Switch one pin 2 to Iso-TK #1 outer rail
Switch one pin 3 Transformer "A" outer rail

Switch one pin 4 --Not used
Switch one pin 5 to Iso-TK #1 inner rail
Switch one pin 6 Transformer "A" inner rail

Switch one pin 7 Transformer "B" outer rail
Switch one pin 8 to Iso-TK #2 outer rail
Switch one pin 9 Transformer "A" outer rail



Switch two pin 1 Transformer "B" inner rail
Switch two pin 2 to Iso-TK #2 inner rail
Switch two pin 3 Transformer "A" inner rail

Switch two pin 4 Transformer "B" outer rail
Switch two pin 5 to Iso-TK #3 outer rail
Switch two pin 6 --Not used

Switch two pin 7 Transformer "B" inner rail
Switch two pin 8 to Iso-TK #3 inner rail
Switch two pin 9 --Not used


When wired up
switches thrown right transformer "A" powered: yard , Iso-TK #1, Iso-TK #2, and Iso-TK # 3 is dead
switches thrown Left transformer "B" powered: main , Iso-TK #3, Iso-TK #2, and Iso-TK # 1 is dead
The plan was to stop the loco on Iso-TK 2
but if the loco's momentum carried it 1/2 way into the next power district. always having one section Dead Iso-TK #1 or Iso-TK #3 their is no chance of it shorting because the loco was not long enough to be able to make contact with both power districts at the same time.

I know it sounds complicated but it worked for me back when TYCO trains and slot cars were the toys all the cool kids wanted

Everybody is making this way too complicated. As long as you have the polarity of the transformers matched there won't be any problem. I have a simple on-off switch for each of the tracks in the yard. I turn the switch on, verify that the direction switch on the transformer is in the right direction and drive the train onto the track.

I have built the on-off-on type of connection you're describing for switching between transformers, but I only use it to control blocks for different operators when we set up a large layout at the NMRA National Train Show. I completely isolate one module and use this set-up to determine which transformer is controlling that module. Its only purpose is to keep trains from running into each other.