gregc sheldon as an engineer, i've struggled to understand others when they dive into a topic or answer a question without providing background or explaining the unque aspects of their problems. BNSF UP and others modeler He wants to know how to wire a wye in DC. ... He can't find anything helpful, and I cant really either. i've made the assumption that the OP is not very experienced with model railroading or at least wiring. i've found your circuits confusing until you explained how they fit into your layout. i think the needs of your layout and your preferences make it easier to understand your circuits. i've felt misled when starting out in various hobbies, when i've tried to follow more advanced hobbyists who do things in ways that were correct for them but unnecessary for a novice to be concerned with, much less appreciate. again, i've learned a lot from this discussion. another tool to consider for solving problems.
sheldon
as an engineer, i've struggled to understand others when they dive into a topic or answer a question without providing background or explaining the unque aspects of their problems.
BNSF UP and others modeler He wants to know how to wire a wye in DC. ... He can't find anything helpful, and I cant really either.
i've made the assumption that the OP is not very experienced with model railroading or at least wiring.
i've found your circuits confusing until you explained how they fit into your layout. i think the needs of your layout and your preferences make it easier to understand your circuits.
i've felt misled when starting out in various hobbies, when i've tried to follow more advanced hobbyists who do things in ways that were correct for them but unnecessary for a novice to be concerned with, much less appreciate.
again, i've learned a lot from this discussion. another tool to consider for solving problems.
Greg,
I understand what you are saying, but I must say I don't agree, and I don't "operate" that way. I do not try to "guess" what peoples needs, experiance level, goals, and prior knowledge base are. I would rather they told me, but in the absence of that, I will still try to offer information. I try to avoid assumptions about others, but sometimes people take suff as condesending either way.......
I have been accused on here before of "talking down" to people because I sometimes over explain......
But I don't, and won't try to decide for others what their needs are. I just try to put well explained information out there for them to use as they see fit.
At every turn you seemed to assume you knew what the OP, or stevetx, wanted to do, and what they did not want to do, or what they needed to know, or not know.
Like some politicians who are sure they know better than I what is "good" for me....
Your mind reading skills may be better than mine.....
Back to the wiring.
DC is a completely different mindset of operation from DCC.
DCC assumes that everyone's highest desire is to be the engineer, to sit in the cab, to turn the lighs on, ring the bell and slide the throttle to the next notch.
Out of necessity, advanced DC looks at the "bigger picture" of how does the single train interact with the whole track "system" and how can easy and prototypical action be achieved.
That does require making choices in advance about operational goals in order to get the best result for those goals.
I once visited a large basement filling layout that had just one DC wireless throttle like the ones I use. The layout is a giant Industrial Switching Layout, the guy only runs one train at a time, he was not into sound, He has tracks he can kill to park locos. Pretty simple.
He does not need my advanced cab control or DCC......
I design all my layout wiring in advance, and build these circuits on the workbench. So hooking them up to the layout is no different than you hooking up some logic module to do the same stuff.
You will need the same inputs and outputs to achieve all the same goals. Logic modules require writing/entering code, my "code" is wires on a panel of relays.
I have described my whole control system multiple times on this forum, I suspect you have seen it.
It provides an operator experiance very similar to DCC with the following goals:
Signals, detection and CTC
Local tower control
Radio wireless throttles
Automatic Train Control - as in the prototype term, trains that run red signals stop automaticly - not an automation of the layout. This feature is largely "free", a result of not using common rail wiring, having totaly seperate power supplies for each throttle, and careful placement of gaps between electrical sections (blocks). Soon I may cover this feature in the thread about my layout move/reconstruction.
Simple easy to use control panels for turnout controls and CTC
It does all this for a good sized layout, designed for 8-10 operators, 30 staged trains, about 8 scale miles of mainline, and it does it for less than decoders for my 130 locos would cost.
I don't make assumptions about other peoples goals in this hobby, possibly because my goals are not typical.....
Sheldon
BNSF UP and others modeler I am back with some explanation. I have been watching this thread, and (in my opinion) it is getting complicated. I work in dcc so that is why I dont know much about this. I also have a workable level of wiring knowledge (I can install a decoder), so that is not the problem. I appreciate the wiring diagrams, but frankly, they are over my head. Hopefully I didn't come across as non appreciative...
I am back with some explanation. I have been watching this thread, and (in my opinion) it is getting complicated. I work in dcc so that is why I dont know much about this. I also have a workable level of wiring knowledge (I can install a decoder), so that is not the problem. I appreciate the wiring diagrams, but frankly, they are over my head. Hopefully I didn't come across as non appreciative...
I assure you, no offense taken in any way. And I hope all my comments have been received in a friendly spirit as well.
I surely understand that many people do not have prior experiance with this kind of wiring. I 'm sure you could learn it, but I understand as well why it may not be important to you.
For me, and many others who have been in more advanced aspects of this hobby long before DCC, these concepts and methods are part of our experiance in the hobby.
I have used DCC, I understand DCC fully and have helped build many DCC layouts. It is actually this experiance with DCC that keeps me using DC.
Respectfully, the skills and knowledge base required for DCC, are dramaticly different then the skills and knowledge base for the circuits I published above. So again, I understand your position.
If, as greg said, the A track is a stub foor turning locos - the same simple setup would work for DCC as well. There's never be a short, no need for an electronic autoreverser.
Yes, the Tortoise contacts are rated to carry 1 amp. But there's no way those little wiper fingers on a PCB trace are going to switch 1 amp. At least on a regular basis. They are fine for frogs because 1) noremally there is ZERO current flowing when the frog polarity is switched (unless you precisely stop a loco right on the frog befor lining the points - but you shouldn't get that close normally). And even if the loco IS parked with a wheel on the frog, other wheels will be on other parts of the turnout, so the current switched throough the frog should be minimal. At MOST, absolute worst case, a 4 wheel loco that picks up from only 1 wheel per side, parked on the frog, yoou'd have a max of one loco drawing current when the frog is switched - not many locos draw 1 amp these days, in HO and smaller anyway. However, oon a full reverse loop, or a wye that is turning an MU consist - now ALL of the track is powered by those Tortoise contacts, not just the frog. 3-4 units MUed, especially with sound decoders with keep alive (thus inrush) - you're going to be switching a lot more than 1 amp. Much better to use the Tortoise contact to trigger a relay with 5 amp or so contacts.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I'm beginning to realize that Windows 10 and sound decoders have a lot in common. There are so many things you have to change in order to get them to work the way you want.
BNSF UP and others modelerHe wants to know how to wire a wye in DC. ... He can't find anything helpful, and I cant really either.
greg - Philadelphia & Reading / Reading
A few points.
First, we have no idea what the OP's real requirements are, he never responded to my offer to post this info, and has not responed at all since my posts begain. It was a different poster, stevetx, who requested I post this.
I'm not assuming the intended use is only to turn locos. In my case, the stub end of the wye is an 8 track hidden staging yard.
Yes, the number of relays, and the features, can be scaled back as needed.
Yes, the A frog can be hard wired to the south rail. As you can see, I omitted all frog wiring, only mentioning it was possible.
Note - I use Atlas Custom Line turnouts, which are feed thru. Users of PECO or other power routing turnouts will need gaps and wiring appropriate for those turnouts.
Again, based on my vast experiance with relays, I would avoid latching relays in favor of hold circuits.
I don't use toggles because of the need and desire to have control stations at multiple locations, local tower panel and CTC panel. And the lighted pushbuttons make a better user interface in a control panel.
The gaps between B and C assume two mainline blocks, which allows one train to exit/enter the wye, while another approches the wye. Again, no assumptions about the desired operations. And again yes, if this is just an engine terminal wye, it can be made much simpler - facts not in evidence from the OP or stevetx.
Since the B and C relays are there, the buffer circuit guards the turnouts in the two block senerio.
Maybe you are comfortable with the 1 amp Tortoise contacts, but I run four unit powered lashups pulling 50 cars, I'm not trusting them for anything beyond frogs or control signals. I know modelers who have burned them up......
And lastly, as a complete layout wiring practice, consistant methods and protocals make for neater, easier construction and easier trouble shooting if necessary.
Of couse as it turns out, the relay cab control system I installed for a fellow modeler, has been trouble free for a decade now.
ATLANTIC CENTRAL As promised, the track power wiring for the automatic wye:
As promised, the track power wiring for the automatic wye:
BNSF UP and others modelerHe 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.
i understand that this is how you wired your wye, that you understand and are comfortable with relay circuits and know where to get them cheaply. I see, because of the 3 relays and the extra gaps, that this circuit can unpower each branch of the wye. But i think this is overkill for a conventional wye as the OP asked about.
for a conventional wye, where the track above A is a stub long enough for a locomotive so that it can be turned, i see no need for the B & C relays. The connections to the uncommon contacts on relay A can be directly to the mainline tracks which you identified as blue and red. And there is no need for the isolation gaps between B & C.
The coloring of the connections between the A stub and common contacts of relay A depends on the position of the relay and would be opposite for the A-C route. Not sure if this is clear to the OP
i'm not sure, but i believe there is no need to power route the frog (if it needs to be), it's always connected to the bottom, red rail of the mainline track.
there is no need for relay A if the tortoise switch contacts are used. If a tortoise is not used, then relay A could be controlled along with turnouts A, B and C using the same switches (discussed previously) to select the route. If a pushuttons are used to control the turnouts, relay A needs to be latching, either a latching relay or a 4pdt relay with a holding circuit. of course, a simple DPDT switch wired as a reversing switch and used to manually control the reversing section polarity.
i don't understand why Randy suggested that the tortoise contacts shouldn't be used to switch the power to the A stub but is ok for the frog. The tortoise auxilliary switches are rated for 1A.
there a several options for wiring a wye. i don't know which is best for the OP. It would be useful for the OP to understand the tradeoffs.
i've learned a lot from this thread. having a good understand of things like this before doing them minimizes the effort, cost and potential rework.
ATLANTIC CENTRALThere you have it, complete control of a DC wye with only three push buttons.
Not a big model railroader, just a switching layout at the moment, but my dad started me with a 4x8 plywood central in 1958. I have been following the DC DCC debate here for a year and have gotten some recommendations from Sheldon on sources to read about re the advanced DC control systems that have been developed over 70 years or so. Linn Wescott, a very bright and resourceful model railroader and part of MR for years desigined his version of DC "route control" and that story ran in 1957, in MR, starting with the May Issue I believe. It is amazing looking back at the history of this stuff, just how good a thinker the men from long ago were, to develop stuff like this. The articles are fascinating and easy to follow, if you understand how basic electricity works.
Many men developed these systems that were constantly improved over many decades. Ed Ravenscroft was a genius and inspired Sheldon. I have read his pieces also and some tremendous thinking went into that too.
Another model railroad electrical genius was Paul Mallery, reading also recommended by Sheldon. Paul was a Bell Telephone engineer that developed many useful things for the telephone company and holds numerous US patents on those. He has written several handbooks on basic electricity for model railroaders. I have the first edition of his 1955 hardcover book, the latest versions of his handbook for model railroaders along with older versions of those books. He was deeply involved in developing transistors so has seen all sides of the model railroad world one could say.
Re the topic at hand he developed a wiring diagram for a wye, with the north leg being a "stub" used just for turning an engine or train, using only one button to operate the wye turnout at the appropriate time. He made it an "X" section as Sheldon has mentioned. I have a diagram of that and will post it if I can figure out how to do so.
The saddest thing is, as Sheldon said here a ways back is to see advanced DC model railroad control systems dismissed as "flipping toggles" as if there is something wrong with that. In 1954 a real train approached a complex interlocking. The turnouts were set to describe a particular route through all of that trackwork. The engineer opened the throttle and just followed that route. On a layout like Sheldon has described, a few buttons are used to set up a route, on his layout, the power is directed to that route, and the train follows it too, just as realistic as the full sized version does. The old timers in this field had more practical knowledge of electricity than most model railroaders of today I suspect. Before you could buy it off the shelf...you had to figure out what you needed and build it yourself. There is a vast amount of PRIDE involved in that. We can learn plenty from the past, of this hobby, if we want to study it! I have nothing but the utmost amiration for the men who proceeded us of today, some of whom were real geniuses in their own right. Advanced DC control systems have a long and good history and are still practical today for those who enjoy that kind of work.
RHM
OK, it works like this:
The wye is a junction between two mainline blocks, lets call them east (on the right), and west (on the left).
Your train is in the east block, headed west toward the wye. If the route is set straight thru on the main, route B-C, and the west block is set to your throttle/train, you proceed thru.
Your train is in the east block, headed west, and now the wye route is set for the wye leg from your direction, route A-C. Your train has power into the wye leg.
After your train is in the wye leg, you change the route to A-B, and you want to reverse your train and back out onto the main.
BUT, your train will still be moving WEST. So you do NOT reverse your throttle direction switch, you simply align the route to A-B, this will effectively reverse the polarity to the train. Your train will now back out on to the mainline still proceeding west, but now in reverse.
After you clear the wye, and set the route back to the main, you could now reverse your direction switch to proceed east, back the way you came.
Other features:
When the route is set to B-C, the rest of the wye is dead, a train or loco can be parked there.
When the route is set to A-B or A-C, the trackage between B-C is dead, preventing a train from the other direction from running the fouled turnout.
There you have it, complete control of a DC wye with only three push buttons.
Remember, with DC, direction is absolute, you are setting the track - EAST or WEST - it has nothing to do with the front or back of the locomotive.
If you use 4PDT relays like I do, there will be enough relay contacts for both the control and track circuits, but you will need repeater relays to drive the switch machines, unless you use the switch machine contacts for the track power.
Again, I only use the switch machine contacts to power frogs. And I need the addtional contacts of the repeaters for the signal circuits.
So the wye becomes one of the more relay intense situations, most others only require one relay per turnout for track power, control logic, and signal logic.
I would not use Tortoise contacts to change the polarity under a powered track. They can CARRY plenty of power to power a frog or whatever, but they aren't rated to SWITCH much power. Plus if you use both sets of contacts to make a DPDT switch, you have no contacts to power the frog or activate signals. What you can do is use one set of Tortoise contacts to power a relay with DPDT contacts. Or glue or some other way attach lever switches so they get activated by the Tortoise arm and use those contacts to switch the track power.
gregc BNSF UP and others modeler He wants to know how to wire a wye in DC. He is working in N scale. regarding the original question ... couldn't the toroise switch contacts be used to reverse the polarity of the wyes reverse section automatically depending on the position of the turnout. as I said earlier, i believe a dual coil (set and clr) latching relay can be used to control each tortoise. three momentary buttons (or pair in parallel) can be connected to the set or clear of the 2 relays for each route. no need for any "explicit" logic
BNSF UP and others modeler He wants to know how to wire a wye in DC. He is working in N scale.
regarding the original question ... couldn't the toroise switch contacts be used to reverse the polarity of the wyes reverse section automatically depending on the position of the turnout.
as I said earlier, i believe a dual coil (set and clr) latching relay can be used to control each tortoise. three momentary buttons (or pair in parallel) can be connected to the set or clear of the 2 relays for each route. no need for any "explicit" logic
Yes it can. My circuit has other benifits, it will insure the whole route is clear before allowing the train to proceed.
Yes, latching relays will work - they cost more money.
Typically, my system uses one relay or less for each CTC controlled turnout. Single turnouts require two, because normally closed LED lighted push buttons are simply not to be found in the size and type I want for my control panels.
But other groups of turnouts generally require only one per turnout, some require only one for two turnouts - it averages out.
The other thing is this, by using the same core circuits, and same parts, there is economy of inventory and method.
The track diagram and its added benifits beyond simply reversing the polarity are coming.
Again, while it may be more than the OP, or Steve, requested, my circuit is part of and Advanced Cab Control with CTC and signals.
Signals only go green when the whole route is clear.......
The contacts on the Tortise machine are not known for their high current capacity. I use them to power the frogs, but avoid using them as the primary path of the track power. But again, I am running DC, andmany of my trains are pulled by three to four powered units.
The ice cube relays have 5 amp contacts, more than my 4.5 amp regulated power supplies that power each throttle.
On my power distribution boards that feed the blocks, contacts are doubled up to handle 10 amps.
BNSF UP and others modelerHe wants to know how to wire a wye in DC. He is working in N scale.
It appears that my request for Sheldon to post his relay circuit for polarity reverse started a very interesting exchange from Sheldon, Randy, Wayne, and Greg. I have enjoyed reading it and am trying to learn. Heck, I wouldn’t know what relay to even buy. I will say that I can at least relate to Sheldon’s Nova - I traded my ‘50 Chevy for a brand new ‘62 Chevy II. I hold two mechanical engineering degrees. I even had an elective circuits class in college around 1960 - we studied tubes. Never made it to relays much less the “new” solid state stuff. My locomotives are all DC steamers that were kits or RTR in the ‘60s and ‘70s. i have done motor upgrades and lots on CalScale. I’ve soldered simple circuits that are published in our magazines because they say which diode, transistor, resister, capacitor, or bridge to use. So, if the relays in Sheldon’s diagram we’re to have part numbers or whatever, I can build it. I’m dreaming of a passenger operations layout in modules based on the Filmore Avenue Roundhouse (it has a great website) but using a reverse loop for return instead of the rolling units. Again, thanks Sheldon for posting the diagram and all you others for helping to lead this old structural engineer thru the relay maze.
Steve
Indeed, newer is not always better. Relay contacts are essentially immune to any power being applied fromt he wrong end. Try that with a lot of power MOSFETs like you'd need to handle equivalent current, and without designing in protection circuitry, you may end up with a slab of inert silicon. Stationary applications, perhaps you have room for ample protection circuitry, but miniatureized applications like DCC decoders - forget it. Notice how quickly a decoder is fried if power gets applied to the motor drive?
I've always been an advocate to switch machine contacts and/or relay to flip polarity for reversing loops, instead of complex electronics. Why detect and then correct a short when you can avoid one in the first place? That DCC makes it stupidly simple since the phase of the signal on the rails has nothing to do with direction of travel makes it even easier.
Jay Leno's steam cars? I'd LOVE to own one like that. About the only thing they don't have compared to a gosline engine car is quick startup. Otherwise - he's gotten a speeding ticket in one that is over 100 years old. They can easily keep up with modern traffic. They are incredibly simple machines, as well, far less complicated than internal combustion vehicle, even a diesel. That fact they they all run, and he is able to drive them, after over 100 years, says something.
I have plenty of tech on my layout, including lots of microcontrollers. But sometimes, the simple ways are better. My servo switch motor controllers - sure, I could switch frog polarity with solid state switches, but relays are dead simple and are easily driven by the micro using a transistor, resistor, and a diode for BEMF protection. I've had great success using the Digitrax PM42 circuit breaker which uses relays. No problems with sound decoder inrush even in purposely contrived tests. They are about the ONLY DCC circuit breaker than actually breaks BOTH sides of the circuit instead of just one leg like all the electronic ones do.
I may have forgotten to mention, and therefor you may be over looking one very important point.
I developed my fully intergrated Advanced Cab Control system for the Aristo wireless throttles more than a decade ago. I have built several versions of its features, on several layouts for myself and others.
When I was developing it, DCC was more expensive than today, and many of the current processor solutions for signaling and control, and other model railroad specific products did not exist.
But here is one of the big things for me, with most anything in my life, I don't replace things that are not broken and still do what I need them to do.
Despite any skills in technology, I don't just upgrade stuff because something new comes along.
In 1996 I bought a high quality lawn tractor, I still have it, it will likely last the rest of my life.
My house has home automation, for some things, and manual mercury thermostats for the five zones of heat.....
I still listen to my 1700 vinyl records - because they are better than digitally stored music. And I listen to them on REAL speakers with 10" woofers, not some "cubes" and distorted base from some electrically processed sub woofer.
I love the MR archives, as a search engine, then I go pull the hard copy from my MR collection, nearly complete from about 1947 to now.
I still have flip phone, because it has better acoustics for talking - I have a Samsung tablet for all that other stuff......
But I really hate touch screens, never to be found in my train room as a control interface. It is after all September 1954 on my layout.......
But I have a smart TV, fully intergated with my HiFi/Suround sound, BlueRay, Netflix, Amazon.........on my fiber optic cable service.....
Newer is not always better, sometimes it is just different....
I have the relays, the Dallee detectors, the Aristo throttles, they work fine, why would I spend more money?
Your questions, perspective and replies are always interesting.
I don't know how old you are, but from my life perspective at age 61, thirty year old cars don't really represent the previous technolgy, this does:
That is me, at age 20, in 1977, I had just finished restoring and hot rodding that 1963 Chevy Nova SS. 283 cid, 350 hp, 4 speed, etc. Did nearly all of it myself, just a little help from dad and a friend of his.
And I will admit, I have no desire to go back to those days for a daily driver....
As I have explained, I have programed PLC's, but for me, building solid state circuits, or programing micro processors, is not much fun.
Buying off the shelf solid state solutions are expensive and often not well suited to specific goals.
Reliablity? Well relays served the signal systems on America's railroad until just recently.......and we are not building the Space Shuttle......
Simpler is a matter of perspective, I will grant that. And as you point out, doing what you know is a big part of that perspective.
Tortoise machine? What kind of switch machines do you use? It has been the dominate product for several decades or more?
Back to cost for a minute. Years ago I looked at all sorts of products to control signals and turnouts, I considered DCC, I considered building my own solid state system, I considered computer/software based systems. In the end, you still need all the same inputs and outputs, and that takes wire - and some sort of "driver".
But in the end, DC with the Aristo wireless radio throttles, and the lighted pushbutton relay based controls for cab assignment, turnouts, signaling and CTC was the lowest cost approach as a total package.
I use one slightly expensive off the shelf solid state item, because I am too lazy to build them - Dallee inductive current detectors. But guess what? They come with a relay built in, ready to interface with my system, no logic interface needed, no "drivers" needed.
24 volt ice cube relays, $3 new, $0.50 surplus on ebay, sometimes less. Never had one fail......
Track power diagram coming soon, either I find that file, or draw a new one......yes its a paper file, and a mylar drawing......
Take care,
Thanks for the additional information, Randy.
rrinker Most of my dislike comes from those Atlas wiring books, which rarely if ever show more than one single feeder to the common rail for the entire layout....
Until quite recently, my layout, about 200' of main line (not counting double track, staging tracks, and industrial sidings) was powered through one wire to the common rail and one wire to the other rail. However, all rail joiners (except those at the bridges, which are removable) are soldered, then gaps were cut where necessary to afford on/off control to some sections of track, usually, but not limited to, passing tracks.When I added the partial upper level, roughly 65' of mainline, and again not counting double track, industrial sidings, and staging tracks, the layout still ran without issue, and that included operations with multiple locomotive on heavy trains and often steep grades. There was never any difference in locomotive performance or a perceptable drop in speed, even when additional locomotives were added.However, after reading of the necessity for additional feeders, even for DC operation, I did relent and added a couple more pairs of wires. As expected, there was no change in locomotive performance, but the wire had been on-hand, so the only expense, a very minor one, was the labour to put it in place.
I will admit that if I had wanted to have multiple operators running their own trains, I'd have likely opted for DCC. However, the layout itself is totally unsuited to such operations, and I'd guess that my layout "design" deliberately reflects my preference for solo operations.
Wayne
ATLANTIC CENTRALRelays 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.
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.
reading about old technology is like looking at a classic car from 30 years ago, a steam engine or many GA aircraft still flying after 50 years. All are fascinating. but technology improves, usually more reliable, less complicated but denser in capability and less expensive.
i'm not that familiar with Tortoise switch machines and had to read about them. Unless your controlling them locally with a DPDT switch, it seems difficult to control them remotely without using a relay of some sort.
I think a latching SPDT relay and a dual power supply may be the least expensive solution to controlling Tortoise machine remotely. And one benefit someone explained to me is that the turnouts remain unchanged from the last time the layout was used. (you can detect the turnout position from the tortoise switches).
it seems that single 12V AC supply and diodes to provide +12 and -12V half wave is a less expensive that having either two +12/-12 or +24/+12 supplies.
while even 4PDT relays may not be real expensive, and while relay logic may not be much more complex to figure out and wire than using TTL for applications on model railroad, it just seems simpler and cheaper to implement such logic in software (leodarno). one leonardo can replace a bunch of relays or TTL gates
it's ironic that i agree that the clicking sounds may be an attraction. And doing things in ways that you are confident in and comfortable with is also very important.
i keep thinking of Jay Leno's steam powered car.
Most of my dislike comes from those Atlas wiring books, which rarely if ever show more than oone single feeder to the common rail fooor the entire layout. That might work on a simple layout, and with very tight rail joiners, but even out 4x8 temporary layout we put up every year had extra feeders - actually, the layout was not common rail at all, all gaps were made with insulated joiners in both rails. This was the way my Dad did it, and he learned electrical wiring in the US Navy, so I figured it was good enough. I just kept doing things the same way when I built layouts myself. Common rail is pretty much right out for DCC, so I haven't had to do anything really different since going with DCC.
Sure it's less wire, but hooking up wires never scared me, even as a kid - I was 5 or 6 when I figured out where my Dad left off on the wiring and completed it and had trains running when he got home from work. Almost everything we had was train set type equipment, even the diesels had split pickup, I don't think ANYTHING we had at the time had all wheel pickup outside of a small 0-4-0 pr a little 4 wheel switcher. It all worked and was easy to understnad = you need 2 wires for a complete circuit and every block had 2 wires, simple and to the point. We used some Atlas components but most of the block toggles were standard toggle switches mounted in a metal strip my Dad made. Another panel with an aluminum plate for toggles and a back plate of plexiglas (so like a triangle with 2 sides) with bolts used as terminals was used to control structure lights and other accessories. Some sections were independent and not connected to the main loops in any way, they just had dedicated power packs. Wish I still had some of the old photos but they have all gotten lost over the years. My Dad built most of it, but I was the only one capable of operating it all without deriling trains.
rrinker...Of course, those books also all showed common rail wiring - which STINKS....
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.
Randy,
Relays are still cheap, plenty of room for them under the layout....
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......
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't come to that for model train control, unless you were really trying to get fancy with the control system. If you use DC coil relays, and run out of contacts, you can 'cheat' and throw in some diodes, much like creating a diode matrix turnout control.
Using the split power supply means that only a single SPDT contact is needed to operate the Tortoise - just like wiring a toggle switch and using a split supply. Common to one side of the Tortoise motor, then +12 through one side of the toggle and -12 through the other side of the toggle. Or relay, in this case. You'd need an extra set of SPDT contacts on the relay to use a single rail power supply, to create a reversing switch.
It also helps, I suppose, that I worked in an industrial setting for a while so the method of drawing relay contacts Sheldon uses is not so odd - it was found in the schematics of many of our older machine tools. And if you peruse some of the older hobby magazines you will see similar drawing elements used in relay-based circuits.
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.
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 & cB = a & cC = 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)?
gregc 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.
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 with and designing relay logic for 45 years. In the 80's I converted lot of these kinds of circuits into software for early PLC's.
https://en.wikipedia.org/wiki/Relay_logic
stevetx 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
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,
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.
stevetx 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
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
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.