ROBERT PETRICKdesign and build a fairly complex, high-functioning layout using concepts and materials available in the DC universe?
i think that's an interesting question. Sheldon has an approach that works for him an presumably a small # of operators. i'm curious about other possibilites.
the answer depends on the # of operators.
presumably not so hard for just a few if one is switching a yard, another running a train on the mainline and another switching a way-freight and possibly work some branch or around the mainline train. the way-freight and mainline may need to share blocks if single track. presumably not with double track. these are my guesses, i'd be interested in hearing from others who have operated such a layout
the one large home layout i know of in new jersey just had tower operators; eight tower operators and dispatcher that configured routes and blocks thru their area and controlled multiple trains with a number of local throttles as the train passed thru.
see chairs in diagram below for locations of towers
after converting to DCC, there is just a dispatcher and 3 tower operators who just align routes. operators control trains using nce throttles. there was an effort to incorporate the remaining towers into the dispatcher, but it was becoming apparent that it would be a lot of work for a single person
i recently spoke with someone having a lot of operating experience who said op sessions having many operators included a dispatcher for aligning mainline routes while way frieght operators could control turnouts with a dcc throttle, but that all turnouts, routes affecting multiple turnouts, could be controlled with throttles if there wasn't a dispatcher
greg - Philadelphia & Reading / Reading
gregc ROBERT PETRICK How is signal logic programmed into the DC system? Obviously, I need to study up on how relays function, but for now I'm just looking for the short answer. doubt the logic is any different. isn't the question how is occupancy detected? would such a system need to latch occupancy so that the occupancy condition remains active when DC power is dropped to stop a loco? "un-latched" when DC power is present but a block is not occupied i thought Sheldon's relay nodes handled this, but i don't don't see where block detection is either done or an input in an schematic (DWG #C-002) i have. hopefully Sheldon can provide a brief explanation
ROBERT PETRICK How is signal logic programmed into the DC system? Obviously, I need to study up on how relays function, but for now I'm just looking for the short answer.
doubt the logic is any different. isn't the question how is occupancy detected?
would such a system need to latch occupancy so that the occupancy condition remains active when DC power is dropped to stop a loco? "un-latched" when DC power is present but a block is not occupied
i thought Sheldon's relay nodes handled this, but i don't don't see where block detection is either done or an input in an schematic (DWG #C-002) i have. hopefully Sheldon can provide a brief explanation
OK guys, you asked a lot of questions today and I was busy visiting my 91 year old mother who is an hour drive away.
Be patient and I will take the questions in small bites.
OK, the signaling is a separate "layer" of wiring, a term Robert will be more than familiar with. But it uses different contacts on the same relays that throw and route control the turnouts.
Next, forget you ever heard the term "latching relay" - they are not used in my system for ANY reason. Relays are better "latched" with holding circuits rather than twin coil latching relays.
At any given monement in time on my system, 30% of the relays are energized and held by a holding circuit, and will stay energized as long as needed. They are rated for continuous duty.
Historic side bar - long before DCC put a constant voltage on the track there were a number of detection circuits that detect locomotives, lighted cars and in some cases resistance wheelsets when the DC propulsion circuit is at zero volts. Just look up Twin T, NMRA detection, etc.
I use inductive detectors that are totally isolated from the propulsion circuit. They will detect parked or moving locomotives and lighted cars. They will not detect resistance wheel sets.
To detect equipment with the propulsion circuit off, there is a high frequency single superimposed on the track that will not move the train, or light a lighted car, and that does not interfere with the Pulse Width Modulated speed control signal, but will trip the detector.
When blocks are turned off, not assigned to a cab, the high frequency signal is still on the rails - the detectors still work.
I will cover more in the next installment - we will get into the signals.
Sheldon
Here is a picture of the detectors I use:
As you might be able to see, its output is a relay.
Signals - the problem with signals is too many people dive into the weeds without understanding the basics. Meaning people worry simulating the more complex signal aspects and often egnore the basic ones.
Lets talk about the signals at a double track set of crossovers - which would be a typical control point on a CTC system. These are absolute signals, trains must stop for red over red.
So as you approach a turnout from the point end you see two signal heads.
Now, the way I will explain this will draw some comments from real railroaders or those deep into the details of the road they model. But what I am describing is how they work, not how crews are taught to read and react to them.
The top signal head shows the status of the main route. If the trunout is aligned straight, and no train is in the next two blocks, that signal will be green, andthe lower signal head will be red. This is a "clear" for the main route.
As soon as you throw the turnout to the diverging route, the top signal will go red, and the bottom signal will go green, again assuming there is no train ahead.
This logic is simple, the turnout position and the detection work together to control the two signal heads.
I will draw a basic diagram of that simple situation.
gregc ROBERT PETRICK design and build a fairly complex, high-functioning layout using concepts and materials available in the DC universe? i think that's an interesting question. Sheldon has an approach that works for him an presumably a small # of operators. i'm curious about other possibilites. the answer depends on the # of operators. presumably not so hard for just a few if one is switching a yard, another running a train on the mainline and another switching a way-freight and possibly work some branch or around the mainline train. the way-freight and mainline may need to share blocks if single track. presumably not with double track. these are my guesses, i'd be interested in hearing from others who have operated such a layout the one large home layout i know of in new jersey just had tower operators; eight tower operators and dispatcher that configured routes and blocks thru their area and controlled multiple trains with a number of local throttles as the train passed thru. see chairs in diagram below for locations of towers after converting to DCC, there is just a dispatcher and 3 tower operators who just align routes. operators control trains using nce throttles. there was an effort to incorporate the remaining towers into the dispatcher, but it was becoming apparent that it would be a lot of work for a single person i recently spoke with someone having a lot of operating experience who said op sessions having many operators included a dispatcher for aligning mainline routes while way frieght operators could control turnouts with a dcc throttle, but that all turnouts, routes affecting multiple turnouts, could be controlled with throttles if there wasn't a dispatcher
ROBERT PETRICK design and build a fairly complex, high-functioning layout using concepts and materials available in the DC universe?
Before I go on with more details, I'm going to answer some of these comments.
"presumably a small # of operators"
I have said repeatedly that on my new layout as designed, there will be at least four mainline cabs available for simultaneous use, and I may wire it for six.
Considering that there will be 12 primary blocks on each loop of the mainline, it could in theory support 6 trains in each direction, based on the two blocks per train requirement.
But given the design of the layout three trains in each direction is a more practical maximum.
That is two or three trains moving east, and two or three moving west. on 240' of visable double track, with train lengths 18' to 25'.
The layout is designed for long trains, most visable blocks are about 25 actual feet long. The hidden staging blocks are handled differently and are longer.
Greg, I am going to tell you right now, the practical way to do a larger layout would be to break it up into serval "divisions", just like the prototype.
"i recently spoke with someone having a lot of operating experience who said op sessions having many operators included a dispatcher for aligning mainline routes while way frieght operators could control turnouts with a dcc throttle, but that all turnouts, routes affecting multiple turnouts, could be controlled with throttles if there wasn't a dispatcher"
So my operational flexibility is similar.
Main line trains - dispatcher can set routes and give permission (assign cabs to blocks) - OR - operators can set routes and assign blocks at tower panels as they walk around with their train. There is a tower panel at EVERY place were routes need setting and cabs need to be assigned to the next block.
I don't really have way freights on the mainline in the traditional sense. most of my industries are not accessed from the mainline.
BUT a few are, and few industrial areas require trains to travel on the mainline to get the the industrial trackage from the main yard. So, like any train out on the main, they would require dispatcher permission for their movments.
Trains in the yard, or on the industrial belt line connected directly to the yard, or switching operations in the passenger terminal do not require the disapatcher.
Yard turnouts, and most industrial area turnouts are manually thrown with ground thows. Because that is who they would be in real life.
One industrial area may require switch machines it is a little bit of a reach.
The passneger terminal has switch machines because the dispatcher can direct trains in and out with the approval of the station agent.
Sidebar - I hate throwing turnouts on a DCC throttle, did a bunch of it on one layout, would never do that even if I went with DCC. Why push 4/5 buttons when you push one? Or throw a ground throw?
Greg, I can see you have a mind that goes everywhere at once, but it might be helpful to get the primary principles down before looking for the solution to every possible senario.
Trains don't share blocks on the prototype as a general rule, so why would we do that ona model? For 100 years the real railroads have gone to great lenght to some two trains from occupying the space at the same time.
There is a point at which it doesn't make any real difference.
Controlling multiple trains on the same main tracks is easier with DCC than DC.
Once you get into signalling systems and preventing signals from being over run (equivalent of PTC, which the prototype has only had for a decade or so) and remote control of the layout, the degree of dificulty goes up such that it really doesn't matter, DC or DCC it starts getting complicated.
For a signal system, other than the occupancy detection method, it really doesn't matter whether it's DC or DCC.
For preventing signal overruns it's probably easier for DC, because the trend in DCC is to actively thwart that feature with keep alives. Even if you totally cut the power the engines are going to keep moving with a DCC keep alive.
Probably the biggest difference is support. Most of the "new" stuff as far as signal electronics and control systems is going to be designed to work in a DCC environment. There are still horse drawn carriages, but all the new stuff is for automobiles.
Dave H. Painted side goes up. My website : wnbranch.com
ATLANTIC CENTRALTrains don't share blocks on the prototype as a general rule, so why would we do that ona model?
Obviously you have never worked for a real railroad. Trains and engines share the same blocks all the time.
ATLANTIC CENTRALFor 100 years the real railroads have gone to great lenght to some two trains from occupying the space at the same time.
Sharing the same space is not the same as sharing the same block. That's why intermediate signals display "stop and proceed" or restricting instead of "stop", so a following train can snuggle up behind the train ahead.
Yes, trains operate in the same blocks all the time. Probably (and certainly dangerously) more so now with that PTC crap.
Not as common back in the day. Communications and signalling werent as modern, reliable, and as specific. ( you know in war time they practically ran them coupled one train to another)
While Railfanning the Southern (yeah I knows its NS) on the north side of 'Dull-Peppah" (Culpepper) Va about a decade ago, I caught a southbound not 5 minutes behind another.
Certainly in different blocks, however, the closeness of the trains and their speed left little to imagine for safety. I asked a retired SR engineer friend of mine who ran that part of the line and in his words -
"Oh yeah, as long as you dont putt'em on the ground or kill yerself, you can run them as close as you can gett'em!"
That indicates same block running but, I think he was pulling my leg!
Clear Ahead!
PMR
PM RailfanThat indicates same block running but, I think he was pulling my leg!
I'm on the tail end of an Amtrak train stopped in a siding and I see a headlight approaching!
IMG_0466 by Edmund, on Flickr
Yep, they came up behind us within chatting distance. As long as they can stop within half the sight distance. Sometimes, as you say, it doesn't go so well.
In Feb. 2001, Amtrak No. 286 left the Syracuse station and should have maintained the speed of the last signal (restricting) but the engineer must have forgot* that (he thought he had a medium) and plowed into a freight just ahead of him. Oops. Maybe that PTC crap would have intervened here?
* Actually the engineer had just begun his run from the Syracuse station so he only had a verbal acknowledgement from the engineer being relieved of what the preceeding signal was.
Cheers, Ed
ATLANTIC CENTRALSidebar - I hate throwing turnouts on a DCC throttle, did a bunch of it on one layout, would never do that even if I went with DCC. Why push 4/5 buttons when you push one? Or throw a ground throw?
beside turnout, some DCC systems support route control where a single route aligns multiple turnouts
ATLANTIC CENTRAL"presumably a small # of operators" I have said repeatedly that on my new layout as designed, there will be at least four mainline cabs available for simultaneous use, and I may wire it for six.
ATLANTIC CENTRALunderstanding of the differing views ... in general.
i thought the comment was about layouts in general, not any one's layout in particular
dehusman ATLANTIC CENTRAL Trains don't share blocks on the prototype as a general rule, so why would we do that ona model? Obviously you have never worked for a real railroad. Trains and engines share the same blocks all the time. ATLANTIC CENTRAL For 100 years the real railroads have gone to great lenght to some two trains from occupying the space at the same time. Sharing the same space is not the same as sharing the same block. That's why intermediate signals display "stop and proceed" or restricting instead of "stop", so a following train can snuggle up behind the train ahead.
ATLANTIC CENTRAL Trains don't share blocks on the prototype as a general rule, so why would we do that ona model?
ATLANTIC CENTRAL For 100 years the real railroads have gone to great lenght to some two trains from occupying the space at the same time.
I understand, I am trying to convey to Greg and Robert how my DC control system works. I only use a limited numbewr of intermediate signals. I am well aware of the details of that on the prototype, but to explain this I am currently dealing just with absolute signals.
gregc ATLANTIC CENTRAL Sidebar - I hate throwing turnouts on a DCC throttle, did a bunch of it on one layout, would never do that even if I went with DCC. Why push 4/5 buttons when you push one? Or throw a ground throw? beside turnout, some DCC systems support route control where a single route aligns multiple turnouts ATLANTIC CENTRAL "presumably a small # of operators" I have said repeatedly that on my new layout as designed, there will be at least four mainline cabs available for simultaneous use, and I may wire it for six. ATLANTIC CENTRAL understanding of the differing views ... in general. i thought the comment was about layouts in general, not any one's layout in particular
ATLANTIC CENTRAL Sidebar - I hate throwing turnouts on a DCC throttle, did a bunch of it on one layout, would never do that even if I went with DCC. Why push 4/5 buttons when you push one? Or throw a ground throw?
ATLANTIC CENTRAL "presumably a small # of operators" I have said repeatedly that on my new layout as designed, there will be at least four mainline cabs available for simultaneous use, and I may wire it for six.
ATLANTIC CENTRAL understanding of the differing views ... in general.
I have explained to you before that my turnout controls also throw multiple turnouts and return other turnouts to their "normal" setting when routes are selected. Often with just one button. This diagram for a wye is one example.
More complex routes are possible.
I don't know any way to explain this other than by example, so constantly asking "what if" before the explanation of each aspect of the system is explained, just makes it harder to convey.
And, as a side note, this drawing and the one you refered to earlier, only show how the switch machines are activated. There are other contacts on these same relays used for track power routing and signal interlocking.
Those are different wiring diagrams.
dehusman There is a point at which it doesn't make any real difference. Controlling multiple trains on the same main tracks is easier with DCC than DC. Once you get into signalling systems and preventing signals from being over run (equivalent of PTC, which the prototype has only had for a decade or so) and remote control of the layout, the degree of dificulty goes up such that it really doesn't matter, DC or DCC it starts getting complicated. For a signal system, other than the occupancy detection method, it really doesn't matter whether it's DC or DCC. For preventing signal overruns it's probably easier for DC, because the trend in DCC is to actively thwart that feature with keep alives. Even if you totally cut the power the engines are going to keep moving with a DCC keep alive. Probably the biggest difference is support. Most of the "new" stuff as far as signal electronics and control systems is going to be designed to work in a DCC environment. There are still horse drawn carriages, but all the new stuff is for automobiles.
Dave, I'm not going to debate this with you. Robert asked a question, I am trying to answer it. I am doing it publicly for others who are interested. If need be, I will do it privately no worries. Since Robert is the person who did the CAD version of my track plan from my hand drawings, we are already in direct private contact with each other.
I have repeatedly explained my reasons for my choices and have no expectations that others should follow my lead.
But apparently some are at least interested in understanding how it works.
I understand VERY well how DCC works. I have used it on the layouts of friends, on layouts I designed for them, for many years now.
I don't need a primer on its "features and benefits" or its short ccomings, extra costs, and extra time investments.
Sheldon, can we move past a discussion of your layout to discuss Roberts specific question? i'm sure there's more than one way
thanks for addressing my questions about your layout.
ATLANTIC CENTRAL
Sheldon, would you mind explaining the symbols in this diagram? what are A, B, C (relay coils)? and what do the LEDs indicate (what does an energized coil indicate). the following may help with the relay symbols
ATLANTIC CENTRALAnd, as a side note, this drawing and the one you refered to earlier, only show how the switch macines are activated. There are other contacts on this same relays used for track power routing and signal interlocking.
not sure about others, but i'm interested in seeing a complete design
Sheldon, please don't confuse these questions with Robert's question
As far as real trains occupying the same blocks and close distances, these distances do not scale down well to our layouts, IMO. Even the biggest blocks that you could fit into a "normal" sized HO layout is probably going to run trains too close together compared to 90% of the time real railroads run trains......even close together.
Compression of the prototype down to our layouts can change the realism quite a bit depending on the situation.
We all understand the visual compromises made when trying to fit mainline running into 24 inch radius curves. And one train on top of another as might be dictated by a fast clock can ruin the realism of the entire layout too.
How much you tolerate these kinds of compressions is a matter of personal taste of course.
- Douglas
Thank you Douglas.
gregc ROBERT PETRICK design and build a fairly complex, high-functioning layout using concepts and materials available in the DC universe? Sheldon, can we move past a discussion of your layout to discuss Roberts specific question? i'm sure there's more than one way thanks for addressing my questions about your layout.
Well, I'm trying to do that. I have already addressed the fundamental needs for his proposed track plan.
Actual wiring diagrams are a building block process of basic circuits. So I was going to try and explain the signals next.
Again, in my view, too many people worry to much about specific prototype advanced signal aspects rather than deal first with the basics of signaling.
gregc ATLANTIC CENTRAL Sheldon, would you mind explaining the symbols in this diagram? what are A, B, C (relay coils)? and what do the LEDs indicate (what does an energized coil indicate). the following may help with the relay symbols ATLANTIC CENTRAL And, as a side note, this drawing and the one you refered to earlier, only show how the switch macines are activated. There are other contacts on this same relays used for track power routing and signal interlocking. not sure about others, but i'm interested in seeing a complete design Sheldon, please don't confuse these questions with Robert's question
ATLANTIC CENTRAL And, as a side note, this drawing and the one you refered to earlier, only show how the switch macines are activated. There are other contacts on this same relays used for track power routing and signal interlocking.
I don't have one giant complete system drawing.
Each layer, cab selection, turnout and route control, detection and signaling, track power routing and dispatcher "permission", have their own drawings.
But they all overlap by using different contacts on the same relays in many cases.
Yes, A, B and C are relay coils. See the little track diagram in the upper right? The dots are the lighted push buttons.
You push button #1, relay coil A is sealed in, its LED lights, and switch motors align that route thru the wye.
Push button #2, coil A drops out, coil B is sealed in, its LED lights up, and the turnouts move as needed to align that route.
And so on.
Meanwhile other contacts on those relays direct track power correctly, power frogs, and provide signal logic.
Here is my problem. I have never had any need to digitize most of these drawings. It will take time to find, scan and publish a few of these.
There are lots of drawings, rather than one big one.
If you look at the lower part of that other drawing you refered to, you will see the part of the circuit that actually operates the the switch motors. That part of the circuit is not shown on the wye control diagram, but would be repeated three times to control the wye.
It is hard for me to repost that other diagram right now, I'm not at my desktop, and to be honest, I'm not all that good doing this stuff on my tablet or phone. And only have partial access to my files.
Doughless As far as real trains occupying the same blocks and close distances, these distances do not scale down well to our layouts, IMO. Even the biggest blocks that you could fit into a "normal" sized HO layout is probably going to run trains too close together compared to 90% of the time real railroads run trains......even close together. Compression of the prototype down to our layouts can change the realism quite a bit depending on the situation. We all understand the visual compromises made when trying to fit mainline running into 24 inch radius curves. And one train on top of another as might be dictated by a fast clock can ruin the realism of the entire layout too. How much you tolerate these kinds of compressions is a matter of personal taste of course.
Prototype practices are interesting. Prototype practices from long ago are interesting. Prototype practices from vastly differing areas of the country (continent) are interesting. But they aren't important for purposes of this discussion. I have long since taken every practice from every railroad that ever existed from all time and from every corner of North America and mixed and mushed them all together and boiled them down into a single proto-freelance modeling design philosophy.
What I'm looking for now is a nuts-and-bolts discussion on how to build and operate a model railroad using DC components. I already know how to do that with DCC stuff. At this very particular moment, I am trying to assemble a shopping list to take to Radio Shack (or whatever its modern-day replacement is). I'm gonna need some relays, I'm gonna need some solenoids, I'm gonna need some resistors, I'm gonna need some wire, I might even need some flux capacitors, I dunno. What do I need, where do I get it, what do I do with it once I got it, and are such things even available anymore?
I hope this discussion doesn't fall off into the weeds.
Robert
LINK to SNSR Blog
What I have always found interesting is people are always saying the proto type did this or that, which may generaly be true but you can always find an example of something else. I have accually seen a billboard reffer on a Union Pacific track siding, looked still to be in use for some reason and was not worn out. Now that was many years ago but still long after they were soposted to be long gone.
Robert, yesterday was very busy for me, but I am going to send a bunch of info directly to you, that way I don't have to put it all on photobucket first.
Robert,
We are in total agreement on the prototype practice thing. My signal system, as I will build it for my layout, is a broad mix and streamlining of prototype practice. Purposely compressed to better suit even a larger layout like mine.
Example, true permissive automatic block signals are something a model railroad does not really need. Who has that much open running mainline with no need for an interlocking?
Even with a 450' mainline in 1500 sq feet, my longest run between two interlockings is barely 60-70 feet. Or about three train lengths. Those two spots have two blocks between interlockings but most interlockings only have one block between them because only one train fits between them comfortably with a little "running room".
ATLANTIC CENTRAL Robert, yesterday was very busy for me, but I am going to send a bunch of info directly to you, that way I don't have to put it all on photobucket first. Sheldon
That's fine. No rush.
We probably should have had this conversation offlist anyhow. I hope I haven't bogged down or inconvenienced any of the other participants.
ATLANTIC CENTRAL I don't have one giant complete system drawing. Each layer, cab selection, turnout and route control, detection and signaling, track power routing and dispatcher "permission", have their own drawings. But they all overlap by using different contacts on the same relays in many cases. Yes, A, B and C are relay coils. See the little track diagram in the upper right? The dots are the lighted push buttons. You push button #1, relay coil A is sealed in, its LED lights, and switch motors align that route thru the wye. Push button #2, coil A drops out, coil B is sealed in, its LED lights up, and the turnouts move as needed to align that route. And so on. Meanwhile other contacts on those relays direct track power correctly, power frogs, and provide signal logic. Here is my problem. I have never had any need to digitize most of these drawings. It will take time to find, scan and publish a few of these. There are lots of drawings, rather than one big one.
At the risk of further muddying the water with a personal anecdote . . .
I used to work for a giant multi-discipline engineering company, and keeping everyone up-to-date on the latest version of the project was always an issue. The civil engineers did their thing; the structural guys did theirs; the mechanical guys did theirs (you'd be surprised how much room HVAC stuff takes up); the architects sat around in their room smoking pipes all day; and if it were up to the electrical engineers, we'd build the entire structure out of Unistrut. It was the advent of CADD that finally put everyone on the same page.
ROBERT PETRICKmechanical
Agreed, as a young draftsman in the dark ages, I worked for both large and small firms. The small ones were much better.
But after a few years I moved into electrical construction project management, where my drafting skills were used for as builts and design/build projects.
ATLANTIC CENTRALThere are other contacts on these same relays used for track power routing and signal interlocking.
can you describe "what" you do to drive signals and manage interlocks.
simplest approach to driving a signal is whether the next block is occupied (and of course APPROACH if the next-next block is occupied).
the next step is to consider turnouts and indicate if a route is not aligned because of open switches
i'm not sure how many truly implement interlocking by ignoring (blocking) interlocking switches that are thrown out of sequence or a block within the interlock occupied. my guess is they signal simply don't show CLEAR when the blocks along an aligned route are unoccupied
sheldon, can you possibly pick a place on your planned layout and describe how you would use your relay board to control signals and turnout, along with any inputs from other node and CTC?
ROBERT PETRICK Doughless As far as real trains occupying the same blocks and close distances, these distances do not scale down well to our layouts, IMO. Even the biggest blocks that you could fit into a "normal" sized HO layout is probably going to run trains too close together compared to 90% of the time real railroads run trains......even close together. Compression of the prototype down to our layouts can change the realism quite a bit depending on the situation. We all understand the visual compromises made when trying to fit mainline running into 24 inch radius curves. And one train on top of another as might be dictated by a fast clock can ruin the realism of the entire layout too. How much you tolerate these kinds of compressions is a matter of personal taste of course. Prototype practices are interesting. Prototype practices from long ago are interesting. Prototype practices from vastly differing areas of the country (continent) are interesting. But they aren't important for purposes of this discussion. I have long since taken every practice from every railroad that ever existed from all time and from every corner of North America and mixed and mushed them all together and boiled them down into a single proto-freelance modeling design philosophy. What I'm looking for now is a nuts-and-bolts discussion on how to build and operate a model railroad using DC components. I already know how to do that with DCC stuff. At this very particular moment, I am trying to assemble a shopping list to take to Radio Shack (or whatever its modern-day replacement is). I'm gonna need some relays, I'm gonna need some solenoids, I'm gonna need some resistors, I'm gonna need some wire, I might even need some flux capacitors, I dunno. What do I need, where do I get it, what do I do with it once I got it, and are such things even available anymore? I hope this discussion doesn't fall off into the weeds. Robert
Too late, LOL.
Yes, compressing prototype practices, proto-lancing them, or free lancing them; a person can have all sorts of practices. It comes down to what they like.
I like simulating trains that are alone by themselves apart from others. If I had more than one train, I'd park the one train on a power routed passing siding before I'd even move the other train out of staging, since the distance from staging to the siding would probably still result in less scale distance than what a prototype would have between trains.
I would think that the operating plan would dictate how you design the layout, then how you would wire it. That would then dictate the number and types of this-n-that's you need from Radio Shack.
As far as the DCC or DC question, I think a person needs to know the "number of trains running per square foot" the layout is expected to support, so to speak.
gregc ATLANTIC CENTRAL There are other contacts on these same relays used for track power routing and signal interlocking. can you describe "what" you do to drive signals and manage interlocks. simplest approach to driving a signal is whether the next block is occupied (and of course APPROACH if the next-next block is occupied). the next step is to consider turnouts and indicate if a route is not aligned because of open switches i'm not sure how many truly implement interlocking by ignoring (blocking) interlocking switches that are thrown out of sequence or a block within the interlock occupied. my guess is they signal simply don't show CLEAR when the blocks along an aligned route are unoccupied sheldon, can you possibly pick a place on your planned layout and describe how you would use your relay board to control signals and turnout, along with any inputs from other node and CTC?
ATLANTIC CENTRAL There are other contacts on these same relays used for track power routing and signal interlocking.
Sure, I will be happy to, that is what I was about to do next in this conversation anyway. But at least part of it will have to wait till I get home today, busy installing about 500 sq ft of hardwood floor.
But to try to answer some of it verbally:
For the sake of this conversation, ignore what you know, or don't know about prototype signal aspects and their names or the specific instructions they convey.
Let's just talk about red and green.
I'm on double track, I am approaching an interlocking that consists of two opposing crossovers (or a double crossover) and a diverging route after route after the crossover.
I am on the right hand track, I have three signal heads for my track.
They are red/red/red, that is an absolute stop.
If the top one is green, I am clear to proceed on the main route I am on. (other heads red in all the following)
If the the middle one is green, I am clear to travel thru the facing point crossover and thru the interlocking into the block onto the left track.
If the bottom signal is yellow (it has no green aspect), I am clear to travel straight thru the crossovers and take the diverging route at a restricted speed.
This is the basic description of how nearly all absolute signals work at interlockings.
This is done with simple serial logic starting at the detector or at the "permission" circuit from the dispatcher/cab selectioin relays.
All signal heads display red until told otherwise.
The logic chain is:
Dispatcher permission - detection - route/turnout position - then to the signal driver.
If all three are satisfied the signal changes to green (or other permissive like speed restricted yellow).
Take one away, the signal goes red.
In this example, the top head logic chain starts with the permission (ownership/cab assignment) of the block straight ahead.
Then it runs thru the detector for that block, and then thru the necessary turnout position interlock contacts, and then to the signal driver.
Going thru the crossover to the left side, that chain, for the middle head starts from that block.
The diverging route may or may not have detection, but it is interlocked in a similar manner with its own serial logic chain.
I will make at least a partial drawing or dig one out of the files.
ROBERT PETRICK Prototype practices from long ago are interesting.
i live near cumberland, where the B&O had to cross the mountains and crested at Sand Patch, PA where helpers were added at Hyndman, PA.
i recently spoke with an older member of the club with railroaders in the family. he said, before OSHA, when the train reached Sand Patch tunnel, the conductor in the caboose closed a brake valve between the caboose and helper engine and was able to lift the coupler pin. with the helper drifting, it pulled away from the caboose and went into emergency braking when the brake pipe broke.
it then reversed into a center track helper pocket and backed down the eastern track to Hyndman
gregc ROBERT PETRICK Prototype practices from long ago are interesting. i live near cumberland, where the B&O had to cross the mountains and crested at Sand Patch, PA where helpers were added at Hyndman, PA. i recently spoke with an older member of the club with railroaders in the family. he said, before OSHA, when the train reached Sand Patch tunnel, the conductor in the caboose closed a brake valve between the caboose and helper engine and was able to lift the coupler pin. with the helper drifting, it pulled away from the caboose and went into emergency braking when the brake pipe broke. it then reversed into a center track helper pocket and backed down the eastern track to Hyndman
It was pretty common on many helper grades, B&O and others, to cut off the pushers on the fly.
Remember, they were no going real fast, 25 mph range at best.
The B&O guickly learned diesels made better helpers and assigned ABBA sets because of their better tractive effort at starting speeds and because the did not need to be turned to work both directions.
So diesels helped steam over those grades for many years in the transition era.