# Figure 8 with MTS/DCC?



## Jerry McColgan (Feb 8, 2008)

I am building a new layout and just now managed to get to the point of powering the two main lines with analog track power. Today I ran a couple of MTH Challengers running on a MTH Z-4000 AC power supply but that will be changed to DC power for analog track power and for DCS with a TIU.












Eventually I plan to run MTS/DCC as well with the layout switchable between power supplies.

The layout is 12' x 40' and the squares are 4'.













With the Figure 8 (in effect a double reverse loop) I realize this is going to complicate the MTS/DCC wiring and while I could use the intended analog polarity reversing blocks I do have the LGB modules to do this with MTS but I have never hooked one up before.

I have not started to try to figure out the MTS/DCC wiring yet or even finished with the analog and DCS wiring but I thought I would start by asking if anyone has wired a figure 8 with MTS/DCC and if there are any special tips I should know about. I seem to recall that the power has to go to the inside of the loop rather than outside the reverse loops and that could prove interesting to run two main lines powered via the inside of the figure 8.

The MTS/DCC power will be via LGB Central Station 2's or 3's with LGB 6 amp power supplies. Obviously I will need some boosters and have some LGB ones for wherever needed.

Comments? Suggestions (other than not to do it)?

Thanks,

Jerry


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## Axel Tillmann (Jan 10, 2008)

Jerry

Somehow I have the feeling, if you isolate the inner cross overs from the ovals, then one single reversing loop could do the trick as long as you don't use the inner part with two trains simulatenously. But in order to keep current to a minimum you would need to run the switch drives (even the internal ones) fromt he out loops instead of short wires to the closet track. But check how much A the LGB reversing loop (which is always a miniature booster) can generate. Zimo has also a 3 segment reversing unit (in one electronic board. If my idea with just one unit doesn't work, then definately the 3 port will will do the trick. Very important is the crossing in your layout, because if the use of one single unit works then you need 100% rail insualation within the corssing otherwise you create short ciruits which typically triggers the protection in the base station and everything comes to a standstill.


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## Jerry McColgan (Feb 8, 2008)

Posted By Axel Tillmann on 04/26/2009 7:32 AM
Jerry

Somehow I have the feeling, if you isolate the inner cross overs from the ovals, then one single reversing loop could do the trick as long as you don't use the inner part with two trains simulatenously. But in order to keep current to a minimum you would need to run the switch drives (even the internal ones) fromt he out loops instead of short wires to the closet track. But check how much A the LGB reversing loop (which is always a miniature booster) can generate. Zimo has also a 3 segment reversing unit (in one electronic board. If my idea with just one unit doesn't work, then definately the 3 port will will do the trick. Very important is the crossing in your layout, because if the use of one single unit works then you need 100% rail insualation within the corssing otherwise you create short ciruits which typically triggers the protection in the base station and everything comes to a standstill.



Hi Axel,

The inner section is 100% isolated from the outer loops and the switches will be hard wired to separate manual controls and power supplies. 

By the way, the Train-Li Dual Track Bender did a great job of reverse curving the outer rail of heavily used 8' diameter curves to put the worn away inside head of the rails to the outside and the unworn outside head of the rails to the inside. In effect the Train-Li Bender returned the correct gauge to the tracks.

Regards,

Jerry


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## Greg Elmassian (Jan 3, 2008)

You can just put a single reverser on the "diamond", BUT, the length of the insulated area needs to be slightly longer than your longest powered car, this includes lighted cars and locos. 

What will happen is that as the train approaches and one wheel enters, the "isolated diamond section", the auto reverser will make sure the "isolated" section is the same polarity as the rest of the loco. Then once the loco is completely in the section, everything stays the same, and when the loco first "leaves" the "isolated" section, it will change the polarity of the isolated section to match the other track. 

Now this will work if only you have one loco at the head of the train, and no lighted car right after. Even then you might have to make a single short "Dead" section on each "leg" of the diamond tracks so that a metal wheel cannot cause a situation for the autoreverser to operate "falsely"... this means something about 1" or less. 

Now if you have more than one powered car, you basically have to have the isolated section longer than the train. This might mean the isolated section starts right off the 4 switches that lead to the diamond. 

All of this depends on train length and lighted cars. If I remember connectly, you like lighted cars, so your best bet is running trains shorter than the "X" part of the track, and never have more than one train in the "X" area. 

Regards, Greg 


p.s. I only addressed the DCC situation. I know you talked about DC too, but I think the complexity is enough that you should solve only one problem, or you will be up to your eyeballs in DC relays!


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## Jerry McColgan (Feb 8, 2008)

Posted By Greg Elmassian on 04/26/2009 9:02 AM
You can just put a single reverser on the "diamond", BUT, the length of the insulated area needs to be slightly longer than your longest powered car, this includes lighted cars and locos. 

What will happen is that as the train approaches and one wheel enters, the "isolated diamond section", the auto reverser will make sure the "isolated" section is the same polarity as the rest of the loco. Then once the loco is completely in the section, everything stays the same, and when the loco first "leaves" the "isolated" section, it will change the polarity of the isolated section to match the other track. 

Now this will work if only you have one loco at the head of the train, and no lighted car right after. Even then you might have to make a single short "Dead" section on each "leg" of the diamond tracks so that a metal wheel cannot cause a situation for the autoreverser to operate "falsely"... this means something about 1" or less. 

Now if you have more than one powered car, you basically have to have the isolated section longer than the train. This might mean the isolated section starts right off the 4 switches that lead to the diamond. 

All of this depends on train length and lighted cars. If I remember connectly, you like lighted cars, so your best bet is running trains shorter than the "X" part of the track, and never have more than one train in the "X" area. 

Regards, Greg 


p.s. I only addressed the DCC situation. I know you talked about DC too, but I think the complexity is enough that you should solve only one problem, or you will be up to your eyeballs in DC relays! 




Hi Greg,

One reason I made the figure 8 with a 30 degree crossover was because it gave me at least 20 feet of fully insulated track for the reverse loops. That will be longer than any trains I will be reversing. With track power it is no problem as I will simply wire a DPDT switch to reverse the polarity as needed (I've done this with multiple analog layouts).

As long as the reversing module can work from the outside loops rather than the power pack having to be fed direct to the crossover tracks I should be OK. I thought I had read somewhere that the reversing loop needed to control the rest of the line rather than be controlled by the mainline. Hopefully I was mistaken.

Thanks,

Jerry


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## Axel Tillmann (Jan 10, 2008)

Jerry - The ZIMO module can pick it up from the track, in case the LGB stuff doesn't.


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## Greg Elmassian (Jan 3, 2008)

Virtually all DCC autoreversers can be fed from the track... and you can make any part of the track the "reversing section". Just remember the basic goal is to have the reversing section longer than the train... I do not think you can do that if the diamond is not part of the autoreversing section, but how about putting some colored lines on your picture to show us what you are thinking? 

Regards, Greg


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