Greetings, all. As I build my layout, I've been intending all along to go with DC, and perhaps change over to DCC at some point in the future. I have carefully selected the turnouts to be DCC-friendly, for example. But I have this wiring logic problem that I'm wrestling with: I have three (possibly four) current tracks, with different parts of the layout wiried to different transformers. There are two main lines (big circles, essentially), plus a yard lead off the inner main line, and the possible fourth circuit for the roundhouse and engine runaround. You can see the layout topology in the first graphic at http://ho.tauxe.net The two main lines, that will be controlled by different transformers, have a double crossover. If the crossover is switched to "straight through", then there is no problem, and the two main lines can be run independently. But when the crossover is switched to cross over, then somehow the two main lines need to be coordinated in both direction and power. I was considering two options, neither of which is particularly satisfying: 1) Wire the power to one of the main lines so that when the crossover is crossed, the main line power also changes to be powered by the same transformer as the other main line. Advantage: The two main lines are powered identically (from the same transformer) so crossing over is guaranteed to be smooth. Disadvantage: At the moment of switching, if the switched main line is not already coordinated (manually) to match the other main line, then there will be a nasty instantaneous change in power (and potentially in direction!) that could be bad. 2) Keep the two main lines powered independently, and trust the operator to make sure that they are in sync when crossing over. Advantage: No potential power jump when flipping the switch. Disadvantage: If the two lines are not coordinated when the crossover is attempted, the engine crossing over will encounter both circuits, and if they are not matched, bad things can happen. To me, the disadvantages are severe in both cases. They both require "manual" coordination of the power packs by the operator. An inexperienced (or inattentive) operator could result in bad things happening, like either a sudden reversal or at least change in power in case 1, and a short in case 2. So far, I have not figured out a way to "idiot proof" the system. I could make the little warning sign, but that's not really idiot proof. Well, I do have one idea: Make a little bar with two holes in it that slips over the two control knobs of the dual power pack, forcing the two knobs to be in the same position. This does not force the direction to be the same, however... I expect that most of you will advise me to go DCC, as that would obviate all these problems. But I have at least one old engine from 1959 (a Gilbert NYC 4-6-4) that I do not expect I can convert to DCC, though I really do not know much about that. So, what I need is some ideas on clever circuitry or perhaps mechanical controls (like the bar?) to force the syncronization of the power packs before allowing the crossover to be switched to cross over mode. Any ideas? HELP!