# wiring for DC two train operation



## airshot

I have recently made a small N gage layout with two mainlines, I would like to have the outside line on one transformer and the inner line on another transformer for switching operations as the turnouts are all on the inside loop. When changing from the outer to the inner (or vise versa) when the loco crosses the isolator won't there be a problem with the loco getting voltage from two power supplies? How does a person wire for this, or prevent damage to his equipment? Thanks in advance

Airshot


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## Southern

Google Atlas Selector. It is the best way to wire your loops.


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## airshot

That part I understand, but won't the loco stop when it crosses the isolator in the track?
If the other power supply was set to run I the opposite direction would the loco suffer damage by having one set of wheels picking up power from one direction and the other set of wheels getting power in the opposite direction? Mabey I am overthinking this, not sure how to wire to cure this problem. Been doing a lot of searching and found a lot of info but not directly linked to two main lines and two power packs. Thanks for your response.

Airshot


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## Southern

first welcome the forum. If you set the switches right on the Atlas Selector you will be able to run it with the same cab across the insulated rail joiner. This is DC not DCC so thing are a lot more durable. Here is a old loco that runs in to a block that has the power reversed. There is no damage.


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## airshot

With your help and my continued research I think I am figuring it out. Your video answered some of my questions, while I would not want to do that all the time, on occasion it will not instantly damage the unit. Thanks.


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## Southern

That old loco is a toy that will not die! I would never do that to one of my high end locos.


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## timlange3

Hi Airshot, you really need to block (electrically segment) your railroad. Usually a block should be long enough to hold an entire train, from the engine to the end. Since you have two power supplies, double pole, double throw switches would be enough to control which power supply goes to which block. You set the switches to connect one of the power supplies to a particular block, so you would always use the same power supply for the same train, no matter where it is at on the railroad. Does that help?


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## Southern

Timlange3 summed it up right


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## airshot

I am going to have to digest that for a few minutes, I think I understand what you are getting at, however on my small layout I am not sure I have enough space. N scale 24" x 48"
with double mainline loops and all turnouts coming off inside loop. I wanted to sererate the outside from the inside so I could continue running the outer loop while switching on the inner loop. I am understanding your suggestions just have to figure out if I could set up blocks besides the inner and outer loops. Many thanks Dang there is a lot to think about when getting started again, guess I forgot an awfull lot from the last time I did this. (20 yrs ago).

Airshot


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## Southern

This is all you need to do what you want.


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## timlange3

Yes, Southern used a picture where I used words. On the selector, four switches, to change between power supply A and B, to go to four blocks. You really don't want to have a train cross from one power supply to another, while running. If the speed and polarity don't match, problems will arise. And if you are running two trains at the same time, you would then have two trains on the same power supply, they will both slow down, or stop, or overload the power supply and trip the breaker.

This type of switch uses a common ground, so you will have less wiring, but more thinking!  Do a Google search on "Atlas Selector wiring" and you will see several pictures about this.

I believe from what you have said you can make the outer oval one block, the switches between the two ovals another block, the inner oval a block, and one or more sidings from the inner oval a block. That would be a minimum and still operate two trains.


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## airshot

You have read my mind on the train running on two different cabs. That was my worry all along, however the latter explanations with the switches and blocks have put me thinking on the right track (pun intended) Many thanks for making me see the light!!

Airshot


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## DonR

Airshot

Both Tim and Southern have been right on
with their suggestions. But, I can see where
you might be hesitant. 

To simplify:

If you use the Atlas suggested by Southern
you would connect your power packs to it.
The you connect the outside track to one set
of terminals on the Atlas and the inside track
to another.

You would put insulated joiners between the
inside and outside track at the turnouts.

With that simple wiring you can have one power
pack controlling a train on the outside loop while
you do switching operations on the inside using
the other power pack. 

You should have one of your 'spur' tracks, isolated
by insulated joiners, powered
thru the Atlas also. That way you can run a loco
onto it, then turn it off, so that you can then
bring the train from the outside loop to the
inside loop. The Atlas controller lets you switch
the inside loop power to that from the power pack
you have been using for the outside loop.

Or have I muddied the waters further?

Don


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## airshot

Actually things are becoming quite clear, it just takes this old brain awhile longer than it used to. But...............we are havin fun!!


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## ckblum

Do you isolate both rails in the track or just one needs to be?


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## DonR

I'm told that Atlas claims you need isolate only one but I
do not know how you can reverse polarity with a common
ground.

I would use an insulated joiner in both rails.

Don


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## timlange3

With the Atlas switch you use a common ground, one rail becomes part of the common ground, so unless you have a reversing section that rail never needs an insulator.


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## airshot

Finally got my switch, so I will be looking closely at their recommendations for wiring, need to upgrade the power pack first. Thanks for all the input.

Airshot


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## airshot

OK, I am getting ready to start the wiring for my switch and making the block sections on the track. After reading....a lot of reading I am still a bit confused on the single common line issue. If the negative side of both power packs become a common line then what will happen when one power pack is put into reverse mode? I will have a cheapie power pack on the outer loop as this will be a train running at a constant speed to get to its destination b4 switching to the inner loop to drop/pickup another load. In the meantime another quality power pack will be on the inside loop doing the switching and yard work which will involve
going back and forth from forward to reverse and back again. What will this do to the common negative line between the two power packs? Do not want to damage the new unit, don't care about the cheapie, but do not want to damage the locos either. Could I get some clarification from some of you electrical experts on here, Thanks in advance..

Airshot


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## timlange3

The potential difference is only between the terminals on one power pack. Putting a Voltmeter on power pack A between the + and - with power on will show voltage, same way with power pack B.

But no matter what polarity you have set or how much power is on, you will never see any voltage between the + or - terminal on power pack A and any terminal on B. The two power packs are isolated from each other because each has its own transformer.

If common ground is too difficult, it was for me at first, took a lot of thinking and talking to someone who understood it. Then I suggest instead of the Atlas Selector you use double throw, double pole, center off switches and wire each block and insulate all the rails. The Atlas Selector should be considered a double throw, single pole, (center off?) switch.


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## airshot

I assume you are telling me not to worry it will be fine, just thought I would propose that question to those who know an awfull lot more about electricity than I do. Hey..if it works and doesn't hurt my equipment then I am all for it. This electric stuff is not my game, I am a skilled toolmaker that works in thousandths of an inch every day and can make just about anything as long as I don't have to wire it. Thanks

Airshot


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## Southern

I works. I thought it would be a problem but it is not.


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## airshot

Now just looking to confirm something here as I begin to wire the layout. I am going to call the positive side power and the negative side common and have marked the rails accordingly.
From what is pictured on the switch box and the plans I have seen online the common (neg) side has no isolators in it? Isolators for the track rails only go into the power (pos) side to create the varius blocks for multi train operation? This is what I see and want to be sure I am understanding this correctly. Not have isolators in the common rail is the confusing part to me, the fear of a short. Looked at this a hundred times to be sure, now just looking for the confidence vote to begin.

Airshot


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## Howard1975

airshot said:


> Now just looking to confirm something here as I begin to wire the layout. I am going to call the positive side power and the negative side common and have marked the rails accordingly.
> From what is pictured on the switch box and the plans I have seen online the common (neg) side has no isolators in it? Isolators for the track rails only go into the power (pos) side to create the varius blocks for multi train operation? This is what I see and want to be sure I am understanding this correctly. Not have isolators in the common rail is the confusing part to me, the fear of a short. Looked at this a hundred times to be sure, now just looking for the confidence vote to begin.
> 
> Airshot



Hello Airshot, yes that is how it works. When using an Atlas Selector to choose which power pack should control which block, only one rail needs to be blocked with insulated rail joiners. Here is a diagram that should help you, a very simple diagram. As long as you have simple track work (no turntables, or reversing loops, or other complicated track work), this diagram should explain things. If you are still confused, just let us know. 

http://s173.photobucket.com/user/JIM_L_R4/media/Jimbasicdc_zpsad69050f.jpg.html


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## trains galore

Hi there!
With my layout I just isolated both rails and use dpdt switches, no common rail
I did it because it was just simple, however you can wire the atlas switches as shown in the link above, you have a common wire (basically connected no matter what) and switch the positive sides of each supply with the atlas switches.
If you have the atlas switches then go with that but otherwise dpdt is just easier (for me anyway) plus you isolate both rails so where you require isolated joiners depends on how you are going to wire it


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## model-a

Southern is right and that is what I was trying to think of that unit he posted is what you need.


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## deedub35

I have just built a HO double oval on a 4x8 sheet. The ovals are connected at one side of the layout with a crossover. On one side of the inside oval there is a turnout for a yard and the other side of the inside oval there is a turnout for a siding. I have 2 Athearn power packs. I am ready to wire this up.

I think I am going to use DPDT toggles and create a control panel. Am i okay with 4 blocks? This would be the outside oval, inside oval, yard, and siding. I would simply cut both rails at the crossover and turnouts.

Do I really need to break the ovals further into smaller blocks? The locos will make a complete loop in less than 10 seconds so I don't always want to be flipping switches. Only when necessary like when changing ovals, yard operations, or parking on the siding.


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## DonR

deedub35 said:


> I have just built a HO double oval on a 4x8 sheet. The ovals are connected at one side of the layout with a crossover. On one side of the inside oval there is a turnout for a yard and the other side of the inside oval there is a turnout for a siding. I have 2 Athearn power packs. I am ready to wire this up.
> 
> 
> 
> Do I really need to break the ovals further into smaller blocks? The locos will make a complete loop in less than 10 seconds so I don't always want to be flipping switches. Only when necessary like when changing ovals, yard operations, or parking on the siding.


No requirement to do so. But, consider that you are going to have two trains
on the 2 tracks and wish to bring the train A on the outer track to the inner where
the train B is controlled by the other power pack and waits. It would be helpful for operations, if you divide the 2 ovals in such a way that you can make this train
movement. It does get tricky. Lotta flippin switches.

I'm restraining myself from mentioning...oh well, I can't hold it in...DCC. 

Don


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## deedub35

DonR said:


> No requirement to do so. But, consider that you are going to have two trains
> on the 2 tracks and wish to bring the train A on the outer track to the inner where
> the train B is controlled by the other power pack and waits. It would be helpful for operations, if you divide the 2 ovals in such a way that you can make this train
> movement. It does get tricky. Lotta flippin switches.


Now that I have thought about it I think I am going to add a siding to the outer oval. This will mean adding another foot to the layout making it 5x8. This will allow trains to park on either oval.

Currently I am going to opt out of DCC simply because I have "inherited" all this legacy equipment. In other words, not having to spend all my money on trains.


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## airshot

OK preliminary wiring with the common is not working. Ran leads to create 4 blocks, tested rails with voltmeter to be sure pos was pos and neg was neg. Added 4 leads to pos side and connected them to selector as shown on dwg. the common leads were connected together and went to neg post on power pack and the pos lead from power pack went to selector cab 1.
I have not cut the rails yet, this preliminary wiring should be same as adding multiple leads to the track for even power distribution, however when I energize the track it shows an overload and nothing works. I have been thru the wires and tested them at least 20 times with a volt meter checking for polarity but have found nothing wrong.
What is a double pull throw switch? Does that mean both pos and neg is on or off at the same time? Mabey I need to go that route, not sure. I know I am uncomfortable with this common lead wiring. Just a thought here....I have turnouts in front and in the back of the two ovals to join them together, even though I checked the rails for polarity and wired accordingly could this be causing a problem? 
My goal is to have two power packs, one running the outer oval, one running the inner oval and the two switch yards which come off the inner oval. I wanted to block the two yards so power could be cut there without interfering with inner oval. I thought the selector would do that and allow me to use either power pack (A or B) to run any of the 4 block areas. Perhaps my thinking is off. Perhaps the experts out there in train land could give some more advice.

Airshot


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## trains galore

I would suggest you do it with dpdt switches, I've never understood the whole common rail thing properly and just wanted it to work so here is my way of doing it, it works for me anyway!

A double pole double throw switch consists of six terminals, by flicking the switch you are connecting one ''side'' of the switch to the middle contacts. The advantage of this is you don't have to worry about common rail etc a you do is connect your block to the middle terminal set and you can send power from whichever set of contacts which you then connect to the controllers, allowing you to connect either controller. You MUST COMPLETELY isolate these crossovers electrically from the inner and outer loops with track joiners, and have them on their own switches.















If you don't understand please ask me again and I'll try to explain better, it took me ages to get it but it is really quite simple with dpdts and they are cheap too

This was the way I did mine and for me it was MUCH easier, so maybe this is the way to go
Here is a quick diagram (if you can read my scrawl


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## deedub35

airshot said:


> OK preliminary wiring with the common is not working. Ran leads to create 4 blocks, tested rails with voltmeter to be sure pos was pos and neg was neg. Added 4 leads to pos side and connected them to selector as shown on dwg. the common leads were connected together and went to neg post on power pack and the pos lead from power pack went to selector cab 1.


You have probably mixed up a connection somewhere so time to troubleshoot.

I would disconnect the Atlas for now and separate all 4 sets of leads. Make sure the ends are not touching each other or anything metal.

Take 1 set of leads and attach it to the power pack. Turn it on. Since all 4 sets of leads are attached to the rails, you should get power at the ends of those unconnected 3 sets of leads. Take your voltmeter and test every set of leads (including the ends attached to the power pack) marking the polarity on the wires with tape.

Disconnect the 1 set of leads from the power pack, hook up the Atlas, and try again.


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## deedub35

trains galore said:


> View attachment 33916


From what I have read in other forums, the center terminals go to the block, the end terminals are attached to power pack A and power pack B respectively.

So when the toggle is at one extreme - power pack A is powering the block. When the toggle is at the other extreme - power pack B is powering the block. When the toggle is in the middle - the block is off.


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## trains galore

Whoops just realised my error
Technically you could do it either way though,(eg switch the controller between two blocks) but I've changed the diagram to the more common method of wiring it thanks for picking that up!


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## Howard1975

airshot said:


> OK preliminary wiring with the common is not working. Ran leads to create 4 blocks, tested rails with voltmeter to be sure pos was pos and neg was neg. Added 4 leads to pos side and connected them to selector as shown on dwg. the common leads were connected together and went to neg post on power pack and the pos lead from power pack went to selector cab 1.
> I have not cut the rails yet, this preliminary wiring should be same as adding multiple leads to the track for even power distribution, however when I energize the track it shows an overload and nothing works. I have been thru the wires and tested them at least 20 times with a volt meter checking for polarity but have found nothing wrong.
> What is a double pull throw switch? Does that mean both pos and neg is on or off at the same time? Mabey I need to go that route, not sure. I know I am uncomfortable with this common lead wiring. Just a thought here....I have turnouts in front and in the back of the two ovals to join them together, even though I checked the rails for polarity and wired accordingly could this be causing a problem?
> My goal is to have two power packs, one running the outer oval, one running the inner oval and the two switch yards which come off the inner oval. I wanted to block the two yards so power could be cut there without interfering with inner oval. I thought the selector would do that and allow me to use either power pack (A or B) to run any of the 4 block areas. Perhaps my thinking is off. Perhaps the experts out there in train land could give some more advice.
> 
> Airshot


One potential reason you are having this problem, is because when you went to hook up both power packs to your layout, but did not cut gaps in the track (and put in insulating rail joiners), you are effectively trying to power your track from both power packs at the same time. You can't have both power packs connected together, and trying to power the same section of track. They will be fighting each other. Especially If they are not in phase with each other (in other words, the power packs are sending opposite polarities to a particular rail), then that is an immediate problem. You must cut gaps in the proper places, and install insulating rail joiners, before you turn on both power packs. I come to this conclusion based on what you wrote. 

A suggestion here. You might want to get a good model train wiring book, either at your local hobby shop, or online. They often have lot's of practical advice, and diagrams and pictures to help makes things clearer. I highly recommend it. 

DPDT (double pole double throw) switches can be used, or the atlas selector. If you decided to use the DPDT switches, people usually put insulated rail joiners in BOTH rails. Something that could be giving you problems with your wiring, is the type (brand) of track turnouts you are using. We don't know what kind of track you have, such as Altas, or Bachmann EZ track, or Kato Unitrack, or Peco, etc. For instance, depending on layout configuration, Peco turnouts often need to be wired a little differently, compared to turnouts made by Altas or Bachmann. It would help if we knew who made your track. Some turnouts have isolated frogs (often made of plastic), but some turnouts have a live frog made from metal, which is always hot. They sometimes need to be wired differently, depending on layout configuration. 

Also need to mention, some turnouts are designed to be power routing (meaning it only sends power to the route the points are aligned), while other turnouts (the non-power routing type) will send power to both routes at all times. They sometimes need to be wired differently, depending on layout configuration.

Sorry to confuse you even more, but we don't know what brand of track or turnouts you are using. It does matter, so we can help you get your trains running fine. 

Here are a diagram that might help you with wiring your layout. 











I hope the text and pictures in the next two links will also be a help for you. 

http://www.all-model-railroading.co.uk/amr/chapter02.htm

http://modeltrains.about.com/od/electronicsdcc/ss/Wiring-A-Model-Railroad-For-Block-Operation_3.htm


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## DonR

Since you have verified your wiring per instructions it
sounds like there may be a short somewhere
in the track. Before changing to the DPDT
switches you need to find out what is
shorting. The following accepts that you say you
have NOT yet gapped or installed insulating joiners.

I suspect that you'll find that you have one or more
common leads on the wrong rail. To find out:

1. Disconnect the leads from the Power
Pack, leave power pack turned off. Also
disconnect the common leads from each other
so that there is no wire connection between
the ovals or between the drops. Set the Atlas
switches to OFF.

2. Set your Multimeter on OHMs. Always check
that's it's working by touching the probes together.
You should get a reading. That is a short circuit.

3. First inspect every inch of track to make
certain no metal object has fallen across
the rails. Look closely at the turnouts and
their frogs. If all is clear:

4. Disconnect the track between the 2 ovals.

5. Again try the multimeter on the rails of
the outer oval. If no reading: The outer oval track
has no short.

6. try the multimeter on the rails of the inner
oval. If no reading: The inner oval track has no
Short.

7. Reconnect the track between the 2 ovals and
test again. You should get no reading, thus your
track is ok.

8. Now connect the common leads of the outer
oval TOGETHER. Does this cause a reading?
If so, one of the common leads is on a wrong
rail. To determine which SEE THE NOTE BELOW.

9. If you get no reading on 8 above, repeat the same
test on the inner oval. 

Comment: I'm thinking you have one common drop wrong
in each oval.
Even just one of the common leads on the wrong
rail would result in a short since
they are all connected together. 

Note: Remember, the color trace idea. Say the top
rail of the outside oval is Red at the top
of the layout. The other rail is Blue. When
the red rail goes around to the bottom of the oval
it reverses and now the bottom rail is red the upper
is blue. The same happens with your inner oval.
Recheck your common wiring to make 
certain the lead is on the correct color rail for both ovals. 
If you have the common on the red rail, it should
never touch a blue rail in either oval. The inverse
would be true with the leads from the Atlas switches.
If one is connected to the Blue rail, all should be connected
to blue rails.

If you have a common on the wrong rail, could you also have
made the same type of mistake with the leads from the Atlas
switches? Do the same Red/blue rail check on those also.

Making the above corrections should now let you connect the
Atlas common rail system as originally planned and it will work.


Let us know.

Don


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## airshot

First of all many thanks for all the suggestions on my wiring delima. I understand the schematic that was posted so let me add some information. Fist of all I have not yet cut the track as it is already glued down and I do not want to do it over. I have the atlas code 80 manual turnouts, with only a 24 x 48 table I can easily reach all of them. For my initial testing I only used one power pack not two. I electrified the track and checked all rails with a multimeter and colored all neg rails with a black marker (yes it was fun getting it all off) from my initial one point connection of power. Then I proceeded to add a power wire to each of the areas I plan to block off in the future and also added a black neg wire on the black rail and brought them together to form a common lead. If all is done correctly The added wires should simply be the same as adding additional jumper wires to power an area of the track that was low on voltage at least that was my plan. Each pos wire from the 4 sections went to selector switch 1 2 3 4, and the black wires were combined into one and attatched to the neg side of power pack. The pos side of power pack went to cab position A on selector (nothing was connected to cab B) With all the selector switches set to position A all the track should be electrified as though I had additional jumpers added. Only first position worked, if any of the other 3 were turned on it showed a short (overload) on the power pack. After not getting much sleep and a long day at work I am going to re-look at the wiring once again to see if I connected something wrong. I checked it 20 times last night but was so frustrated I may have over looked something. My goal was to see if the common rail was going to work before I started cutting anything. 
Thanks again
Airshot


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## trains galore

Yes certainly do the test DonR has suggested.
The causes of shorts I have found on my layout have been:

1. When a train is crossing over a block, if the polarity of that block is opposite to the rail the train is on than you will get a short as positive will short out to negative when the metal wheel touches.
2. When my track was not properly isolated, I would get shorts if I tried to run controllers in different directions for pretty much the same reason.
3. If your feeds are incorrectly installed they will cause an instant short circuit (ie wrong polarity to track, they MUST be the same.
Good luck


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## airshot

You all have restored my faith.......I would like to tell you folks something I learned today, do not trust your multimeter to tell pos from neg. As described earlier I had marked the rails with black for neg power and retested it tonite before starting over. My wiring was correct according to the multimeter (MM) so I disconnected each pair of wires and tested them individually and wouldn't you know, two pr were reversed. when I switched them around everything worked great. Here is the clinker....when I retested with the MM it shows a reverse polarity on those two pair. Don't ask me to explain, cause I couldn't if I wanted to, however the suggestion to check each pr as individuals was the key as it showed up right away. Also found a bad solder joint so repairs are underway and we are off and running again
that is until the next problem occurs!! Again many thanks, will keep everyone posted on my progress or mabey recession which ever it may be..........

Airshot


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## Howard1975

That is good news. Glad I could help. Once you get everything sorted, and working well, you will be able to enjoy running your trains. 

And by the way, your choice of switches, the Atlas code 80 turnouts, does make the wiring simpler with two connected loops. Some brands are a little more difficult to wire correctly, when you have two track loops connected. 

Howard


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## DonR

Airshot

The multimeter will always show the correct polarity
reading DC voltage.

However, if on test A the Red probe was on Rail X
and Black probe on Rail Y, and you got a - in front
of the reading indicating a negative voltage,
then on test B the Red
probe is on rail Y and black probe on Rail X your
reading will be drop the - indicating a positive 
voltage.

It's important to use the probes consistently.

Sure happy you found the problem. If anything
crops us, give us a shout.


Don


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## airshot

While I have no explanation of why it showed opposite I can say I did have the probes on the correct rails. First of all I had the neg rail according to the meter totally marked in black marker around the entire track and turnouts so I would not mistake which was which. After 
figuring out what was going on I even went back to the original setup to prove to myself that I was not reading the meter incorrectly. The wiring is working now on each of the 4 block areas using the selector switch, however on two of the block areas it shows opposite polarity than it does on the other two. If I switch them back to show same polarity it creates an overload on the power pack. I still cannot explain why or how, perhaps it is a cheap Chinese
meter I don't know but what the hey, it works so who cares.
My job requires me to look for potential problems so I guess I carry that trait into my hobbies so I am now looking at another possible problem with the common rail wiring in that if one cab is running the outer loop and the other is running the inner loop and doing some switching will there be a problem when the inner cab switches into reverse as the polarity will reverse on the common rail?? Or will this be OK and become a mystery to me like the polarity change in my meter? Thanks again

Airshot


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## Howard1975

It will not give you any problems, as long as you wire everything properly. The other important thing to remember is, as long as the common rail is kept solid (no insulating gaps) when using the Atlas selector and your Atlas switches, you will be fine. You will only need to cut gaps (or use plastic insulating rail joiners) in one rail, not both. The common rail will have zero insulating gaps. The only exceptions are reversing sections: reverse loops, wyes, and turntables. With reversing sections, you must insulate both rails in the correct areas. 

I know it sounds so strange, how can electricity function this way. I don't really understand all the technical jargon either, but I know it does work. It is easy to set up and wire once you understand the concept. It's learning and understanding the concept that takes time, because it seems impossible. But the fact is:

A power source (those electrons) always must return to its own source. How common rail works is you MUST use two (or more) different transformers, one for each cab; otherwise both cabs on common rail would create an immediate short circuit. With two (or more) isolated transformers, where neither can interfere with each other, it will work fine. 

This common rail concept will NOT work if you are using any type of reversing track arrangements, such as reverse loops, wyes, or turntables. They need insulating in both rails.

Even when everything is wired correctly using the common rail method, there is a potential problem when you move from one block to another, which are controlled by different power packs. 


The issue that some people have, is when a loco crosses the gap between blocks that are set to different cabs (power packs). This will connect powerpack A output to that of powerpack B. If both power packs are set for the same direction and speed, there will be little or no voltage difference when the locomotive crosses the gap - which is no problem. But if they are set to different directions and/or speeds, there will be a voltage difference across the gap, and a short between the two blocks (power packs) will result. That's why it is important to have your blocks set correctly ahead of your train, when you are running with cab control -- no matter how it's wired; ie: with common rail or not. 

With any cab control block system (common rail or not), you need to be careful that your train is always under only one power pack, anywhere you travel on your layout. 

It does not matter if you have 100 blocks, and 10 different people each with their own power pack (like very large club layouts before the days of DCC), the electricity will work fine. That is provided the layout is wired correctly, and every person keeps their locomotive inside there own block(s). Often with regular cab control layouts, a person will have selected 2 or 3 different blocks for his single train -- the block the train is inside right now, and the block it's going to next, and for a short time the block he was just in. Once the train has completely left a block, you release it back to the pool of blocks available for anyone to choose. Which you do by switching that block back to the center (neutral) on the atlas selector. That way another operator can quickly see, that block is not occupied and can be used by his own train. 

Howard


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## DonR

Howard has done a good job of explaining the need of careful operations
when you have a DC layout with blocks that can be fed by 2 different power packs.

I've been there, done that. It can be tricky. In addition to tending the train
speed and the position of turnouts in the route, you have to lead the train by
flipping switches so it has the right power.

And that's why, more and more of us are now running our trains
without that concern with DCC.

One positive note, tho, Airshot. When you do win the lottery and
want to go DCC, all you have to do is turn all those switches to
ON A and connect the DCC controller. That's it. No more wiring hassels.

Don


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## airshot

Most of the time I will be the one in control of the switches and blocks, it has always been my intention that when a loco moves across a block both blocks will be under the same cab control to prevent any problems. the other cab can sit idle for a few minutes while this is taking place. It pays to be president of your own railroad, you can make these things happen!
Oh yes the lottery....when that day happens I won't be worried about model trains, I will then buy a full size RR and won't have to worry about wiring...LOL..

Airshot


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## DonR

:smilie_daumenpos:


airshot said:


> Oh yes the lottery....when that day happens I won't be worried about model trains, I will then buy a full size RR and won't have to worry about wiring...LOL..
> 
> Airshot


Spoken like a REAL rail fan. 

Don


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## airshot

Well she is up and running, made the cuts and used some extra stakes from an N scale flat
car, mixed up some JBweld dipped the little stake into the mix and slid it into the slot. When hard used an exacto knife to trim then filed to match rail. Ran the engines around on each of the 4 blocks and tested both cab controls. And yes it does work when one is in reverse and the other is in forward...I won't even try to explain but a big "THANKYOU" to all who responded and helped me thru this. Playin is now going to be a whole lot more fun....that is until I win that lottery !!

Airshot


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## Howard1975

That is wonderful news Airshot, your trains are working for you now. Glad I could be of some help.

And yeah, when you do win that lottery, and you can buy a full size RR, there is no need to wire it. It's self powered. It's all ready to go, just add water, LOL. Well you know what I mean. 

It would be fun to climb abroad your locomotive and run it. 

Howard


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## trains galore

Good to see you got it all running it's part of the fun of modelling is solving a frustrating problem.
And when you win the lottery buy some live steam:laugh:
That would be awesome!


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## airshot

Trains galore.......I love your signature, it is true for most of us guys, get a chuckle every time I see it.


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