Atlas 3-rail turntable wiring

Are you attempting to run the PW stuff and the command stuff at the same time?  That would pose a problem I suspect, but you can certainly run them separately without issue on the same TT.

My plan is to have designated tracks for each train control - post war and DCS. My problem is, how do you wire a setup like this, where you can park these trains in the roundhouse using the same turntable.

I'd just wire the TT to a switch that switches between the conventional and command power sources.  The actual tracks inside the roundhouse would be dedicated to a particular type, or they could be individually switched between the two if you wanted flexibility in using each bay for command or conventional.

 

I don't see any particular issue with running both using one TT.

 

Obviously, the track(s) coming up to the TT will have to reflect your operating mode, are you having a single track coming in, or two?

 

Two maybe more. I have not yet made the layout - still in the planning stage.

Well, this part doesn't seem to be a particularly troublesome issue, it can be wired to accommodate your desired operating mode.

 

You say it CAN be wired, my question is HOW? Dale H posted some stuff about relays, but not enough to get me through this. Again, I will be running PW Lionel and modern MTH ps3.0 on separate loops going into the Atlas turntable (3-rail #6910), and then into the roundhouse. I would like to get them across the turntable and into their garage, and than be able to bring  them back on the main line. What kind of relays? What kind of toggles? Where do I connect the wires? Too many questions- I am not the smartest kid on the block, but I am willing to learn.  Thank you all.

I have not yet figured out how to wire this TT.

Let me suggest one possible solution that will keep it relatively simple:

 

1.  Forget about relays.

 

2.  Use DPDT (double pole, double throw) center off toggle switches.  There are six terminals on the bottom of the toggle switch.  First set up a uniform standard for all your toggle switches:  Top three terminals for center rail, bottom three terminals for outside rails.  Two left side terminals to conventional power source.  Two right side terminals to DCS or PS3.0 power source.  Center two terminals to track.  

 

3.  Use a toggle switch for each "garage" or roundhouse track and another toggle switch for the turntable bridge.

 

4.  Flipping each toggle switch in one direction will connect the track to which it is wired to the conventional power source, flipping it in the other direction will connect it to the DCS or PS 3.0 power source.  Moving it to the center will stop power from either source from reaching the track.

 

Hope this helps.   

 

To help clarify:

 

Terminals A, C, and E are for center rail power and connections.

 

Terminals B, D, and F are for outer rail power and connections

 

Terminals A and B are connected to conventional power source

 

Terminals C and D are connected to track

 

Terminals E and F are connected to DCS/PS3.0 power source. 

Truthfully, there is no need to switch the outer tracks, I'd just common all of them.

 

Agree, and understand that common rail wiring on the outside usually should work but . . .

 

Trying to keep it simple and preclude any possible complications from either "home run" wiring for DCS or phasing of separate power supplies.

Well, phasing is an issue anyway, because if they're phased wrong, when you crossover you could have a problem.  I'd be much more inclined to make SURE they are phased properly than to depend on never having a switch in the wrong position and driving onto the TT or into the engine house. Having rails not phased is an invitation to disaster!  No reason to switch more than you have to, you're also introducing more connections and more possibility for problems down the road.

 

The common outside rail isn't a problem for DCS, or all the folks like me running TMCC with DCS would be pulling our hair out.

 

I suggested one possible solution; others are certainly free to propose theirs. 

when saying "phased wrong", do you mean like the U terminal and the A terminal are not connected the same, or does it mean something else? I will be using a Lionel ZW transformer for the older trains, and an MTH 1000 through an MTH  TUI, to power the modern trains.

There are two places where phasing matters.  One is at the terminals to the track (the A and U terminals or equivalent) and the other is at the plug into the house current.  The plug into the house current is the usual source of problems although with polarized plugs the problem is less likely now than before polarized plugs.

 

If you do have two totally separate loops it would not be an issue.  CORRECTION:  Would be an issue at the turntable where the potential would exist for serious problems.  Please see my post below.

 

As GRJ wrote, you could go to Single Pole Double Throw (SPDT) toggle switches connected only to the center rail as long as your power sources are in phase and the outside rails form the common rail for electrical purposes.   

After corresponding with GRJ, he got me to realize I should not have discounted the importance of phasing as there is the potential for serious damage to electrical and electronic components if a locomotive crossed between two tracks that are out of phase with each other.

 

Recommend using this thread: https://ogrforum.com/t...sing-on-transformers, note especially the link to the tutorial at the end.

 

 

SO, WOULD IT BE BETTER AND SAFER, TO USE THE DOUBLE POLE SWITCH, AND SWITCH BOTH RAILS, AS OPPOSED TO USING A SINGLE POLE SWITCH AND SWITCHING ONLY  THE CENTER RAIL?

IMO, there is no need to switch the outside rails, and you're just adding wiring that serves no purpose.  If you make sure all the power sources are in phase, just switching the center rail will accomplish what you want to do.

SO, WOULD IT BE BETTER AND SAFER, TO USE THE DOUBLE POLE SWITCH, AND SWITCH BOTH RAILS, AS OPPOSED TO USING A SINGLE POLE SWITCH AND SWITCHING ONLY  THE CENTER RAIL?

No, it would not be better.  

 

GRJ's solution is better than what I originally suggested.

 

A SPDT center-off toggle switch is like the picture above but with terminals B, D, and F missing.  So all you have to do is wire terminals A, C, and E.  

 

Basically, the outside rails are unswitched; they have a constant and common return to the ground terminal of both transformers or power sources (usually the U terminal on Lionel transformers and color coded black terminal on some MTH transformers).

 

I think GRJ is making your life easier here. 

 

Just one more thing I want to emphasize: make sure you get center-off toggle switches or you will have big problems with your conventional locomotives on their roundhouse tracks.  As it is, you will need to be very careful about using the toggle switches because if you have a conventional locomotive on a track and you move the toggle switch for that track to DCS/PS3.0, the locomotive is going to take off like a bat out of you-know-where.