So, I have a question from a friend. He wants to know how to wire a wye in DC. He is working in N scale. He can’t find anything helpful, and I cant really either. Any help would be greatly appreciated. He has one atlas controller to work with.
color me skeptical. It’s just a reversing loop and Atlas controllers have been around a while.
A good book might be an good investment.
https://www.amazon.com/Complete-Atlas-Wiring-Book-Scales/dp/B0006KSLE6
A less expensive book: https://www.ebay.com/itm/EASY-MODEL-RAILROAD-WIRING-1990-PRACTICAL-FLEXIBLE-WIRING-FOR-ANY-LAYOUT/283027440197?hash=item41e5c00245%3Ag%3AIXYAAOSwhHJbCmDl&_nkw=easy+model+railroading&rt=nc
and if you don’t want to wait for the post office
Atlas Controller shown below with reverse loop (upper diagram). Ignore the Selector modules on the right that control blocks off to the right. And you can ignore Cab B, as it is not required to have 2 cabs (to operate two trains) for a single train with mainline & reverse loop.
The X-Y direction switch (that reverses the loop ploarity) and the Cab A direction switch are used when needed to ensure (1) that the loop polarity matches mainline polarity when & where (depending on turnout poition) a train enters the loop and (2) that the mainline (Cab A) polarity is matched as needed to the loop polarity when the train then exits the loop. I forget exactly how used as I am a DCC guy lately.
http://download.atlasrr.com/pdf/Item220Instructions.pdf
Unfortunately that does not show the wye approach on track isolation & connection specifically but it indicates where an isolated (reversing part) of the wye is connected to the controller X-Y direction switch output. Basically the wye must be separated into a mainline section and an isolated “reversing” section. I noted elsewhere that the isolation can be one rail in some cases but needs to be both rails in others, depending on the turnout type.
There are various wye diagrams around but I did not find everything you need to know in one place using the Atlas Controller. I would suggest using Atlas devices and getting this book which surely explains it all.
https://shop.atlasrr.com/p-8-complete-atlas-wiring-book.aspx
https://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=atlas+wiring+book
Since I was snarky in my initial response, I will say, on behalf of the OP, that the above diagram does not help me understand how to use an Atlas controller in this application, which is a black box to me. Yes, I looked at the pdf mentioned above and I don’t speak electrical diagrams.
35 yrs ago I used dpdt switches for my reversing loop, not an Atlas controller. If you call what they call the “isolated section” in your pic the mainline and everything past the gaps, the reversing loop it looks like every other diagram of a reversing loop if you ignore there are turnouts instead of a continuous loop.
The “automatic reversers” used in DCC cannot be used in DC. But 2 DPDT switches cost no more than a draft craft beer.
The new Atlas plans are just that, track plans, even though a lot of them come froom the old Atlas books. The OLD Atlas books, by Armstrong and Stepek (yes, THAT Armstrong) used to show all the wiring with Atlas components. Including layouts with reverse loops and wyes.
Of course, thoose books also all showed common rail wiring - which STINKS. But the Atlas components are all designed for common rail wiring. Back in those days, even going back to when I was just a wee lad, we NEVER wired the layouts for common rail. It just isn’t how my Dad did it, and I just carried on with my own layouts. I always gapped BOTH rails, and ran two wires fromt he block toggle to the section. Not a common rail in sight. Skip the common rail, wire it like Greg showed, DPDT toggle switches are not expensive.
–Randy
i provided some information. I didn’t think the OP was asking about Atlas and I don’t know what level of understanding the OP has
i assume the OP is capable of asking, and will ask questions.
In addition to the diagram shown above with the DPDT switch, a wye with at least one dead end can be made fully automatic with a few relays connected to the turnout positions.
You simply need to understand the DC wiring principal of EAST-WEST, and the reversing section can be controlled by the route chosen.
I will post a diagram later when I have access to my desktop.
It can be wired so that a single pushbutton for each of the three routes will throw the necessary turnouts and set the polarity correctly.
The magic of hard wired logic…
Sheldon
Sheldon, I would like to see you post the diagram you discussed with push buttons and relays to control polarity for a reverse “Y”. Could you include the part number or whatever for the relays. I am all D.C. and wanted to do one of these relay systems a few years ago but I just couldn’t find the circuit and what relays. Thanks
I will be happy to. Just give me a few days to dig it out, get it scaned, etc.
We are getting ready to move, and life is busy.
But I will get it posted for you.
Sheldon
Steve,
OK, here is part of the wiring. The following two diagrams show how to control the turnouts of a wye with only three push buttons that select the route, not the turnouts individually.
The first diagram shows how three relays and three lighted pushbuttons select the routes.
On the second diagram you would only use lower part of the schematic marked as “typical-most turnout comtols”, and it would be duplicated for each of the three switch machines controlled by relays A, B, and C.
Later I will publish the diagram of rail gaps and how extra contacts on A, B, and C are used to control track power and polarity.
Sheldon
Sheldon,
Thanks for the awesome diagrams. I will study them and learn. Hopefully, i can build that. Cool that it’s only three push buttons. Looking forward to your gaps for polarity control.
Steve
Steve,
I don’t know what your electronics background might be, but it is pretty easy to build this stuff.
A few tips in understanding this stuff.
The diagrams always show the state of relay contacts with the power turned off.
Multiple events will/may happen when the circuit is powered up, or when a button is pushed, you have to remember that electricity moves at near light speed, so think thru the events as if it was slow motion.
Example in the top diagram, with the power off there is no thru route, note the little arrow marks on the small track diagram. As soon as the circuit powers up, turnout relay B is energized and the mainline route is set thru. Everything then moves from there as you select a different route.
More later.
Sheldon
some explanation would be helpful. i’m an EE and some of the symbols are unfamiliar.
it looks like the R1 and R2 inside circles are relay coils and the symbols that look like capacitors with and w/o a diagonal line could be relay contacts, closed and open when relay active?.
i see one contact with an R1 and fours thers with an R2. But it’s not clear which contacts are closed with the relay active and in active.
it looks like the R2 relay contacts on the bottom connect the tortoise switch machine, SM, to either 24V or gnd.
it looks like the the buttons and relay contacts energize one relay or the other and the contacts hold them.
there are two pairs of button for the dispatcher and local. one actives R1 and the other button R2.
Repectfully, I will be happy to explain. It may be symbols from before your education, but they are standard symbols used in the days of relays. This method of diagram drawing is called a ladder diagram. It makes no atempt to group relay contacts with their coils physically.
A capacitor symbol has one line curved…
That is a normally open contact for the relay coil indicated. A slash thru that symbol is a normally closed contact. Circles with numbers or letters are relay coils unless othewise described.
The state of the circuit is always shown with no power on. There are no solid state components in this circuit except resistors for LED’s, shown as a box with an R, just relays, buttons, relay contacts, and the switch machine coils.
Yes, the normally open buttons energize the relays and contacts hold them on until something else turns them off. Relay circuits like this are very common, motor starters on industrial equipment for example.
Hope that helps.
Happy to explain more. I’m not an EE, but I was trained by a very good one and I have been working wit
even though the symbols may be standard, it doesn’t mean the logic is obvious. This is my first taste of relay logic, so i’m curious.
i think the first diagram controlling the wye turnouts for each route needs some explanation.
i believe the switches, labeled 1, 2 and 3 control the three wye routes. 1 is A-right/B-left, 2 A-left/C-right and 3 B-right/C-left.
i believe the A, B and C in circles represent a relay that controls multiple turnouts. i’m confused about it’s relationship to the turnouts labeled A, B and C.
it would also be helpful explain what happens when when switch is pressed, explaining how multiple relays are affected.
i think the logic is (where capital mean active and lower case inactive or NOT):
A = A & b & c
B = a & c
C = C & a & b
i believe a button forces a relay to become active. the logic to maintain/hold a relay requires the other two relays to be inactive, so forcing a relay to be active with a button, forces the other relays to become inactive through the contacts holding them.
it’s not clear how the A, B and C relays or circuits actually control a turnout (secondary contacts)?
Greg, you pretty much have it. A few details.
Each relay is directly linked to one turnout. The relays used have four sets of form C contacts (4P2T)
One set of contacts is used to drive the switch machine, see the lower portion of the second diagram. That circuit is used for each relay/switch combination to actually drive the switch machine.
Next, on the small track diagram, note the small arrows next to each turnout. That represents the position of the turnouts with their relay de-energized.
So, when the control power is turned on, by default, relay B will energize, that turnout will change position, completing the straight thru route on the wye.
At that point, if you push the button for the A-B route, relay A is energized, relay B drops out, both of those turnouts change position to the A-B route. Relay C is uneffected.
Similarly, if you then push the button for A-C, relay C is energized, relay A drops out, and route A-C lines up, turnout B says in its default branch position.
And, once again pushing the button for the B-C straight thru route, will energize B and return us to the B-C route.
Additional relay contacts will be used to automaticly route DC power only to the selected route, and in the correct polarity.
I will post this diagram in a day or two.
Additional questions welcomed.
Sheldon
Not sure how to explain it better than Sheldon is - despite being a child of an 80’s era EE education, my model railroad learning back in the early dyas was based a lot on 50’s and early 60’s era publications, so the relay logic concept is not so odd to me. What a world we live in today - transistors that are more sensitive AND can carry more power than those used in the original Twin-T detector are available for pennies. The ones used in the Twin-T were several dollars (in 1958 dollars!) each. Ones that could handle the current to run trains or even woorse, the demands of the common twin coil switch motors of the dya, were not easily affordable to the casual hobbyist - that did chnge quickly however. Relay logic was the order of the day - plus no worries about running a relay in some “in between” state instead of fully open or fully saturated. Relays were cheap as surplus, and it was hard to damage one, unlike a relatively fragile germanium transistor.
SO basically what happens is you use the contacts of ooone realy to controlt he coil of another - or a combination of contacts from several relays. By wiring them in different manners you can easily mimic any logic get you want. If the path is in series through the NO contacts of relay A and then through the NO contacts of relay B to get to the coil of relay C - you have an AND gate. A and B have to be energized before C energizes. If either A or B is off, or both are off, C cannot turn on. Parallel the NO contacts of A and B to feed the coil of C, and you have an OR gate. If A or B, or both, are on, C can turn on.
With enough contacts, you can make as complex a logic as you might need - remember before the first vacuum tube coomputers, there were computers built with relay logic. If the design gets too complex, you might be able to simplify the whole thing by applying Boolean algebra - or if yoou had a digital logic course, use a Karnaugh map to generate simplified equivalent logic. Probably wouldn&
Randy,
Relays are still cheap, plenty of room for them under the layout…
And they make neat 1950’s clicking noises…
Split power supplies do all kinds of neat stuff…
I actually looked into using PLC’s or other solid state logic - for these circuits, and my signals, relays are cheaper, and as stated before, less layers.
In my signal system, the actual lamp power goes right thru relays on the Dallee detectors, then thru interlocking logic of the turnout relay contacts, then right to the signals and panel lights - no separate logic level and driver level.
Turnouts are all controlled with circuits like the two published here. Occasionally some relays need more contacts and get repeaters.
And the cab selection circuit is eight relays on a custom circuit board, so it is prewired. Just hook up the panel buttons and the cab power buss, and connect two wires to the track block.
There are hundreds of them, but at any given minute, only 20% or less are energized, so power consumption is minimal.
Until the mid 1980’s, these kinds of circuits ran every kind of industrial machinery.
I started working in commercial/industrial electrical engineering and construction in 1975…
We did a job in 1981 where we replaced the controls for one of the most critical sewage pumping stations in the Baltimore system.
About 200 relays controlled three 700 hp, 2,400 volt, variable speed pump motors. I had to convert the ladder diagrams of the relay circuits into program code for Cutler Hammer PLC’s. I was 23 years old…
That station is still running on that equipment from what I understand…
Sheldon
Randy, I’m curious about your comment on common rail wiring. I use it on my DC powered layout, and it allows me everything I need to run my one-man operations. I didn’t use the Atlas controllers, though, as I thought them to take up too much room. Train control is through walk-around throttles.
The layout is point-to-point (several points) and has a wye and two turntables, controlled with dpdt switches, and rotary switches for engine terminal tracks. The wiring was very simple, and has been trouble free.
Wayne