Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

DC wiring question on a new layout

8457 views
104 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Monday, June 14, 2021 10:44 AM

Again Mike, without seeing your track plan, it makes little sense, but it seems you might have figured it out.

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 5:21 PM

gregc

 

 
ATLANTIC CENTRAL
???????

 

sorry, wrong wording.    the right hand screw terminal of all but the last 220 have both cab connections

 

OK, yes, no worries.

To me, this is all so much easier to simply build with toggle switches, assuming this kind of system is all you need.

And in doing so I would not use common rail in building the layout or use a common wire return.

One day I will draw some more drawings and show the advantages of not using common rail.

The OP has received my PM and we are communicating about his layout plan and wiring needs.

I will repeat, the very best DC control systems, assuming you want to control mutiple trains at once, do not use toggle switches, and do not have to tie the operator to a control panel, despite all "toggle flipping" comments I have heard in the last decade.

Sheldon

  

    

  • Member since
    July 2009
  • From: lavale, md
  • 4,117 posts
Posted by gregc on Sunday, June 13, 2021 4:50 PM

ATLANTIC CENTRAL
???????

sorry, wrong wording.    the right hand screw terminal of all but the last 220 have both cab connections

greg - Philadelphia & Reading / Reading

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 4:32 PM

gregc

 

 
CSX Robert
"Non-reversing" does not pass both legs through to the output terminals.  Only the center position passes both legs to the output. In both of the other positions, one leg of the input is connected to common and not connected to either output terminal.

 

yes.  measured with a multimeter.  thanks

so if you center them, the last 220 doesn't see both power pack connections

 

???????

The drawing on the instructions you posted is perfectly clear. The middle position passes the power thru, bypassing the common wire connection. 

The right most Controller does see both power pack conncections but is does not pass them both thru. It creates the common wire connection and only feeds the two hot feeds (top and bottom right side terminals) from each power pack on to any #215 selectors used for block control.

And the right most Controller is used as the primary direction switch for each throttle.

I don't see what is so hard to understand here? Maybe it is just hard for people who have not built or operated a DC layout with cab control to see the end result?

Common rail or not, reverse loops need to get their power BEFORE the primary reversing switch for the rest of the non reverse loop blocks - that is the primary function of the Atlas Controller.

Second, the reverse loop block needs to be able to select which throttle will control it - the Controller does that as well.

By being able to stack them, you can have as many reverse loops as you may need.

The Selector then allows all other blocks to be connected to cab A or Cab B or turned off to isolate a loco/train.

Sheldon 

    

  • Member since
    July 2009
  • From: lavale, md
  • 4,117 posts
Posted by gregc on Sunday, June 13, 2021 3:11 PM

CSX Robert
"Non-reversing" does not pass both legs through to the output terminals.  Only the center position passes both legs to the output. In both of the other positions, one leg of the input is connected to common and not connected to either output terminal.

yes.  measured with a multimeter.  thanks

so if you center them, the last 220 doesn't see both power pack connections

greg - Philadelphia & Reading / Reading

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,042 posts
Posted by CSX Robert on Sunday, June 13, 2021 3:00 PM

gregc
so there's reversing, non-reversing and pass-thru?   what's the difference between non-reversing and pass-thru

"Non-reversing" does not pass both legs through to the output terminals.  Only the center position passes both legs to the output. In both of the other positions, one leg of the input is connected to common and not connected to either output terminal.

  • Member since
    July 2009
  • From: lavale, md
  • 4,117 posts
Posted by gregc on Sunday, June 13, 2021 2:48 PM

sheldon has said (PMs) that i like to know "why".

Lastspikemike
The 220 reversing switch has a center off but this position passes through the connection so isn't really "off".

clearly there needs to be a position when the paths between the screw terminals are isolated, before switching connections.   the  left screw terminals can't be connected to both screw terminals on the right at the same time otherwise there's a short.

but it appears the right 1/3 of the switch position is the reversing position and the left 2/3, including the center is the non-reversing position.   i was able to find a spot where there was no connection

because of this asymmetric construction, it makes sense, as Sheldon says the instructions indicate, to center the cab reversing switches in all but the rightmost 220 to indicate that they shouldn't be used to switch mainline polarity.

CSX Robert
The center position of the cab reversing switches on the 220 are "pass-through", i. e., they pass the left hand cab inputs directly through to the right hand cab outputs.  Neither of the other positions is pass-through.  They both connect one leg to common and one leg to the output and they swap which one is connected to the common versus the output.  In both non-center positions of the switch, only one leg of the input is connected to the ou

so there's reversing, non-reversing and pass-thru?   what's the difference between non-reversing and pass-thru

greg - Philadelphia & Reading / Reading

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 2:40 PM

Overmod

 

 
Lastspikemike
one of our group of three worked as an electrician years ago and to him white was the hot wire). 

 

OK, I'll bite on this.  In what retarded imitation version of the NEC or any other valid national code does 'white' denote 'hot' instead of neutral?

 

In part I'd like to know because I found a "professionally" wired job in Springhill where the wires mysteriously changed colors passing through a junction box.  I attributed this at the time to guild malevolence against 'outsiders' messing with electrician prerogatives (NEC's position being no colors are 'official' and you should always check before tinkering anyway) but perhaps this is some distinctive color aberration taught to apprentices?

 

OK, wires in conduits should always be white = neutral, hot or switched hots other colors based on voltage/phase.

But, in cable assemblies like ROMEX, there is no code requirement to mark white wires uses as hot legs on switch leg circuits.

If in the time I have been away from the code book this has changed, I assure you such a requirement is seldon inforced.

Open up that three way switch in your hallway, and you will find a white (or two) on the switch being used as a hot wire. 

Depending on how the whole 3-way circuit is wired, you will also find a white wire spliced to a black wire in a box somewhere in that circuit.

Same with dead end switch legs, now prohibited by the code. A single black and white cable assembly going to a switch, the neutral stopped at the light fixture.

Recent code changes require neutrals in all junction and outlet boxes. Why? To provide a neutral for home automation devices.

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 2:24 PM

CSX Robert

 

 
gregc
...any reversing switch has just to positions, if not center-off, non-reversing or "pass thru" and reversing.     ... think about it.   why would it have a pass-thru and non-reversing position?
 

 

 

The center position of the cab reversing switches on the 220 are "pass-through", i. e., they pass the left hand cab inputs directly through to the right hand cab outputs.  Neither of the other positions is pass-through.  They both connect one leg to common and one leg to the output and they swap which one is connected to the common versus the output.  In both non-center positions of the switch, only one leg of the input is connected to the output.

 

That's what I see on the diagram, but I don't have one in my hand....

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 2:23 PM

Lastspikemike

A DC primer would be handy.

I have a common rail system in that all my red wires are connected and three throttles are connected to all the red wires ( although some of the red wires are actually white because one of our group of three worked as an electrician years ago and to him white was the hot wire). 

So, I admit to becoming confused again. Since two of the three throttles are in a MRC 780 then clearly I'm not experiencing the internal short problem. We routinely have the powerpack reversing switches opposed.

My remark about train direction was a serious remark.  We have two loops and one connecting track. The "outside rail" of one loop connects to the "inside rail" of the other loop. We can't have a consistent East West or clockwise and counterclockwise. One loop is always the reverse of the other. The connecting track has neither an inside rail nor an outside rail. No left or right rail if you prefer. 

 

Once again, a drawing or picture would be helpful.

Sheldon

    

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,042 posts
Posted by CSX Robert on Sunday, June 13, 2021 2:21 PM

gregc
...any reversing switch has just to positions, if not center-off, non-reversing or "pass thru" and reversing.     ... think about it.   why would it have a pass-thru and non-reversing position?
 

The center position of the cab reversing switches on the 220 are "pass-through", i. e., they pass the left hand cab inputs directly through to the right hand cab outputs.  Neither of the other positions is pass-through.  They both connect one leg to common and one leg to the output and they swap which one is connected to the common versus the output.  In both non-center positions of the switch, only one leg of the input is connected to the output.

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 2:21 PM

gregc

 

 
ATLANTIC CENTRAL
I'm going by the drawing and memory, I don't have one here to test.

 

i do have one and i verified it after.

any reversing switch has just to positions, if not center-off, non-reversing or "pass thru" and reversing.     ... think about it.   why would it have a pass-thru and non-reversing position?

 

I agree, just looking at what Atlas says in both pictures and words....

Sheldon

    

  • Member since
    September 2003
  • 19,023 posts
Posted by Overmod on Sunday, June 13, 2021 2:12 PM

Lastspikemike
one of our group of three worked as an electrician years ago and to him white was the hot wire). 

OK, I'll bite on this.  In what retarded imitation version of the NEC or any other valid national code does 'white' denote 'hot' instead of neutral?

In part I'd like to know because I found a "professionally" wired job in Springhill where the wires mysteriously changed colors passing through a junction box.  I attributed this at the time to guild malevolence against 'outsiders' messing with electrician prerogatives (NEC's position being no colors are 'official' and you should always check before tinkering anyway) but perhaps this is some distinctive color aberration taught to apprentices?

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,042 posts
Posted by CSX Robert on Sunday, June 13, 2021 2:10 PM

Lastspikemike
The two "up down" coloured schematics seem to show the short circuit I refer to. The opposite polarities of the powerpacks connect at the Common terminal. That looks to me like a dead short. Why is it not?

This is confusing for many people when they first look into common rail wiring.  Take for example a single 12 volt isolated power supply.  The '+' terminal on that power supply by itself is not actually +12 volts, it is +12 volts relative to the '-' terminal of that power supply.  The voltage at any single point has to be measured relative to some reference point.  With two separate isolated power supplies there is no common reference point.  With common rail cab control wiring, you are creating a common reference point - the common rail.  The control rail can be made positive or negative relative to the common rail by switching the polarity of the cab controlling that rail.

It's kind of funny in way, many people have trouble with hooking the '+' of one power supply to the '-' of another, yet most of them have done the same thing putting batteries in a flshlight without thinking twice about it.

  • Member since
    July 2009
  • From: lavale, md
  • 4,117 posts
Posted by gregc on Sunday, June 13, 2021 1:53 PM

ATLANTIC CENTRAL
I'm going by the drawing and memory, I don't have one here to test.

i do have one and i verified it after.

any reversing switch has just to positions, if not center-off, non-reversing or "pass thru" and reversing.     ... think about it.   why would it have a pass-thru and non-reversing position?

greg - Philadelphia & Reading / Reading

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 1:31 PM

Ablebakercharlie, I sent you a private message. With any luck the little word "message" to the right of your screen will be red and you can access my message and respond.

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 1:02 PM

tstage

 

 
ATLANTIC CENTRAL
Keep this in mind, electricity is magic, you have never seen it, you have only seen what it can do.......

 

You have if you've watched a good lightning storm...or the original Frankenstein movie.

 

I know you're just poking fun, but actually no, lightning is the ionized light produced by electricity, still not the moving electrons.

As a working electrician, I make "lightning" sparks all the time on purpose. When we want to turn off a low amperage (120v, 15/20amp) circuit we are working on, we often just short it out and trip the breaker - presto, the circuit in question is off and easy to identify in the panel.

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 12:55 PM

gregc

 

ATLANTIC CENTRAL
The cab reverse switches on the ADDITIONAL Controllers must remain in the center pass thru position on those controllers.

 

the center position (there are no detents) disconnects the ride side terminals from the input side on the left .   the left position is a pass thru, the right position reverses (verified with multimeter)

 
 
ATLANTIC CENTRAL
Only the right most Controller is used as the MAIN LINE reversing switch.

 

i agree because any other would also reverse the polarity going to the X-Y reversing switch

 

 
 

I'm going by the drawing and memory, I don't have one here to test. I sold them to a lot of people, I helped friends wire them years ago, but I never used one on my layout. I had real toggle switches, even at age 12......

They show three positions on the diagram? The instructions clearly say "center position"?

Does not matter, fact remains on intended operation as I described, all additonal Controllers to the left for additional reverse sections should have their cab reverse switches NEVER used and left in whatever position provides pass thru.

Maybe with some luck today I will find my 1957 copy of the Atlas wiring book.....

Sheldon

 

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 12:42 PM

Lastspikemike

I know assignment of polarity of the main powerpack is arbitrary but that's not the same thing as there not being plus and minus.

Another aspect of the way ours was wired is to have the reversing switches all set to the same direction for the same train direction.

Anyway, it appears that my particular situation related only the the internal wiring of the MRC 780 which did not show on the schematics so usefully provided in this thread.

Thanks. I believe I now understand. In effect, the MRC 780 does assign polarity but only internal to the powerpack. MRC seems not to mention this as far as I can see. 

 

The Atlas instructions clearly tell you not to use the reverse switch on the power pack - common sense might suggest putting them all in the same position, checking output polarity, and wire the whole system consistantly.

YOU just repeated in different words something I have been saying to you for months and you kept ignoring or challenging - the idea that the direction switch position should be consistant with direction of travel.

I am working on a solution of this OP, and if I have time over the coming week, maybe like my thread about trucks, I will develope a DC Primer, because it seems many who never really used DC to run their trains have very little understanding of its basic principles.

Sheldon

    

Moderator
  • Member since
    June 2003
  • From: Northeast OH
  • 16,590 posts
Posted by tstage on Sunday, June 13, 2021 12:35 PM

ATLANTIC CENTRAL
Keep this in mind, electricity is magic, you have never seen it, you have only seen what it can do.......

You have if you've watched a good lightning storm...or the original Frankenstein movie.

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 12:32 PM

Lastspikemike

Well. I'll be darned. Right and wrong at the same time.

Now I understand why my particular arrangement "worked funny". The MRC 760 we connected as a third Cab to run the yard (waste of a powerful throttle that was) never could play nice with the 780. Interesting sparking effects over our Peco diamond crossing and the voltage problem Mel kindly warned me about at one Electrofrog turnout, which we solved by gapping properly and making sure the blocks were always switched properly for through trains.   

When we moved the layout I connected the MRC 760 to Cab A and the second throttle of the MRC 780 to Cab B on the 220 gang. Now the 780 is performing a more usual function of running the mainline from one throttle and the yard from the other. The yard Cab doesn't need to go through the 220. The MRC 760 connects to the whole layout through a 215 selector switch which treats the entire yard as a block from the 760 operator's perspective all the Cab A yard block switches are connected through the one block switch in series with the 220. Cab B connects to all the yard blocks through that same single selector switch. 

Originally, I couldn't quite figure out the wiring I now use. I still can't figure out how to connect three Cabs to the entire layout using the 220 to control reversing sections. We used to have three reversing sections but we now realize you only need two maximum for any layout, to be able to run  any train in either direction anywhere. 

 

ALL of this is exactly why I have little use for conventional power packs, and less use for the Atlas system.....

EVERY DC layout will have a different best solution based on track plan and operational goals.

There is no GOOD "one size fits all".

I have not seen your track plan since you refuse to post drawings or pictures, I have limited understanding of your goals. So I will not presume to know what is best for you.

But I feel fairly confident that when you offer others advice on this topic, it is HIGHLY colored by you own view on what the goals are, and your own experiance meeting your goals.

Respectfully, my experiance has bit more depth, being both an electrical designer who has designed many DC systems for many layouts and having spent years behind the shop counter helping other modelers, so I don't presume to know what others need or want until I am told so.

Sheldon

    

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 12:21 PM

Lastspikemike

Well, I'll check it again someday. At the moment both my view of the schematic, my testing with my multi meter and my experience wiring ganged 220 say otherwise. I wired ours up wrong and they didn't work. Wiring them correctly, not as shown by Atlas, worked. But then I was connecting a MRC 780 twin throttle powerpack to the 220's.

DC powerpacks have positive and negative output terminals or they wouldn't need a reversing switch to operate trains. Multimeters display reversed polarity, digital with a minus sign and analogue by driving the needle backwards. 

I still say that because the C terminal has to feed the reversing section terminals and that only one polarity reaches the block selector switches that it matters which way around the four input terminals on the 220 are connected to the two powerpacks. But I'm no electrical genius so I may be mistaken. 

Heck I still think all the Cabs must have the same polarity terminal connected to the common rail.....

 

As Kevin pointed out, the reverse switch on the power pack changes the polarty of the output terminals, so there is no plus or minus terminal.....

Your last statement about common rail and polarity does make it clear you are not an electrical genius and that you don't understand transformer theory or DC theory.

Hooked up as intended, and used as intended, the Atlas system works fine.

BUT you cannot use dual packs with a single internal transformer as I stated above, and you need to follow various established conventions regarding reverse sections and common rail.

Use whatever terms you want Mike, but if you want people to understand you, there may be an advantage in using already established terms and definitions......

I power my signal system, cab selector system and switch machines with a multi phase dual voltage power supply that supplies both 24vdc and 12vdc. The first thing you do to build such a system is connect the positive terminal of one DC power supply to the negitive terminal of another DC power supply...... simply magic.

Keep this in mind, electricity is magic, you have never seen it, you have only seen what it can do.......

Sheldon

    

  • Member since
    July 2009
  • From: lavale, md
  • 4,117 posts
Posted by gregc on Sunday, June 13, 2021 12:07 PM

sorry.   it seems i'm just adding to the confusion

CSX Robert
gregc
the arrow is confusing in the controller schematic (upper right). there is a permanent connection between the screw terminals.   I verified this with a multimeter with the reversing switches centered.    they've confusingly drawn the connection going thru the switch.

you're right, i'm wrong, there is no direct connection between the cab reversing switch and the output terminals (right side) 

the cab A screw terminals on the right side go thru the cab reversing switch, allowing the polarity on the right side terminals to be reversed.

CSX Robert
  The other two positions connect one leg of the corresponding cab to the outer output terminal (top terminal for cab A and bottom terminal for cab B) and the other leg to the common terminal.

i believe you're saying that the cab-A reversing switch also connects the C (common) terminal at the top of the controller to bottom cab A screw terminal on the right side.   the top cab A screw terminal on the right side is the non-common rail connection

CSX Robert
 
gregc
and yes, if the plastic cab reversing switch is in the middle, there is no connection between common rail terminal, C, power pack.   The switch should not set in that position

The switch is supposed to be set in that position on all but the right-most controller when there are two or more.

ATLANTIC CENTRAL
The cab reverse switches on the ADDITIONAL Controllers must remain in the center pass thru position on those controllers.

the center position (there are no detents) disconnects the ride side terminals from the input side on the left .   the left position is a pass thru, the right position reverses (verified with multimeter)

CSX Robert
  
gregc
the bottom diagram also indicates that the common rail connection C is from the right-most 220 controller, meaning that it is the result of passing thru several cab reversing switches on one or more 220 controllers as well as the throttle itself.

The common does pass through all of the controllers (on the cab inputs/outputs), but you cannot pick it up until the last one because you cannot determine which leg of each cab is common until after the reversing switches in the last controller.

that's what the diagram shows

ATLANTIC CENTRAL
Only the right most Controller is used as the MAIN LINE reversing switch.

i agree because any other would also reverse the polarity going to the X-Y reversing switch

Lastspikemike
Did we also verify that, assuming the two power packs depicted by Atlas are identical, that Atlas shows the positive and negative outputs connected incorrectly to the 220? If yiu connect as shown you will get a dead short. 

why?

for separate cabs there are no common connections between the cabs unless one output is connected to AC ground

Lastspikemike
DC powerpacks have positive and negative output terminals or they wouldn't need a reversing switch to operate trains.

of course the output i DC.  the reversing switch is between the output terminals and the circuit inside controlling the output voltage.   that is why polarity is not marked on the output terminals.

greg - Philadelphia & Reading / Reading

  • Member since
    September 2003
  • 19,023 posts
Posted by Overmod on Sunday, June 13, 2021 11:04 AM

Lastspikemike
I wired ours up wrong and they didn't work. Wiring them correctly, not as shown by Atlas, worked. But then I was connecting a MRC 780 twin throttle powerpack to the 220's.

Remember what Sheldon said a little earlier

IMPORTANT - the Atlas system, and common rail in general, will not work with dual power packs fed from a single internal transformer. You will get a short when you hook up the common wire and reverse the direction of one throttle in relationship to the other.

If I recall correctly the 780 is one of those with a common primary and the equivalent of two taps to supply the two 'cabs'.

I think it's time for 'chapter 2' of the explanational posts, about how the various DC devices actually work (and, in some cases, fail to work as expected).

 

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 15,950 posts
Posted by SeeYou190 on Sunday, June 13, 2021 10:03 AM

I do not understand labelling power pack track outputs.

The track output is polarity reversable by the direction switch on the power pack. It does not have a positive or a negative.

Confused

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,042 posts
Posted by CSX Robert on Sunday, June 13, 2021 9:51 AM

Lastspikemike
Did we also verify that, assuming the two power packs depicted by Atlas are identical, that Atlas shows the positive and negative outputs connected incorrectly to the 220? If yiu connect as shown you will get a dead short.

No we did not verify that because it is not true.

Ignoring the cab selector and reversing switch for the reversing (X-Y) section, ther Eare five settings for 220.

The first setting has both cab revresing switches set to the middle position.  It connects the cab A and B inputs directly to the right hand side outputs and leaves the C terminal unconnected (Edit: I meant to point out in that anything marked in yellow in these diagrams is unconnected):

202

Here are the other four combinatons (I've labeled the switch postions up and down to match the schematic even though physically they are left and right) :

 Up-up

Up-down

 Down-up

Down-down

For each cab and each position, one input is connected to the outer (upper cab A, lower cab B) output terminal for that cab, the other input is connected to the common terminal, the inner output terminals are left unconnected, and there are no shorts anywhere.

  • Member since
    January 2009
  • From: Maryland
  • 11,778 posts
Posted by ATLANTIC CENTRAL on Sunday, June 13, 2021 9:32 AM

Robert gets it.

The Atlas Controller serves three functions. It provides a MAIN LINE reversing switch for each throttle AFTER a power tap for a reversing loop. It provides a cab selection switch for the reversing loop, and it provides the necessary separate reversing switch for that loop.

IF you have more than one reverse loop, Controllers are added to the left for each additional loop.

The cab reverse switches on the ADDITIONAL Controllers must remain in the center pass thru position on those controllers. Only the right most Controller is used as the MAIN LINE reversing switch.

For what it is, the Atlas system works fine, you just need to set it up correctly and know what each switch does and know which ones to leave alone.

And maybe, you need to accept the established conventions of MAINLINE and REVERSE LOOP?

IMPORTANT - the Atlas system, and common rail in general, will not work with dual power packs fed from a single internal transformer. You will get a short when you hook up the common wire and reverse the direction of one throttle in relationship to the other.

Over the years many better dual packs actually had separate internal transfomers because common rail was popular back in the day.

You must have a separate transformer (derived source) for each throttle to use common rail for multi train cab control.

For those who don't undertand this, I will explain transformer theory and why you don't get a short with two separate power packs some other day.

Meanwhile, I am working on a best design for the OP's track plan.....

Sheldon 

 

    

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 15,950 posts
Posted by SeeYou190 on Sunday, June 13, 2021 8:58 AM

Lastspikemike
And what would that be?

I think you are purposely "playing dumb" to start some discord. There is no way you do not understand common rail.

Anyway... common rail has one continously electrically connected rail that shares one terminal in common with each power pack output. That "rail" is "common" to all power sources.

There, now you don't need to pretend that you don't understand.

Zzz

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,042 posts
Posted by CSX Robert on Sunday, June 13, 2021 8:42 AM

gregc
the arrow is confusing in the controller schematic (upper right). there is a permanent connection between the screw terminals.   I verified this with a multimeter with the reversing switches centered.    they've confusingly drawn the connection going thru the switch.

The arrow is just showing one position of the reversing switch.  There is not a direct connection between the cab input and output terminals, the cab reversing switches are three position switches and the center position does connect the inputs straight to the outputs.  The other two positions connect one leg of the corresponding cab to the outer output terminal (top terminal for cab A and bottom terminal for cab B) and the other leg to the common terminal.

gregc
and yes, if the plastic cab reversing switch is in the middle, there is no connection between common rail terminal, C, power pack.   The switch should not set in that position

The switch is supposed to be set in that position on all but the right-most controller when there are two or more.

gregc
the bottom diagram also indicates that the common rail connection C is from the right-most 220 controller, meaning that it is the result of passing thru several cab reversing switches on one or more 220 controllers as well as the throttle itself.

The common does pass through all of the controllers (on the cab inputs/outputs), but you cannot pick it up until the last one because you cannot determine which leg of each cab is common until after the reversing switches in the last controller.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!