Wiring signals for 'hands off' mainline traffic

[ereimer]

Digitrax's big book just went on my shopping list . thanks Modeloldtimer

[davekelly]

Modeloldtimer,

I knew there had to be an easier way to do it!!

[Modeloldtimer]

Hi, jshrade
Yes there is a way to control the starting (Acceleration speed )and the (Deceleration ) or stoping speed in DCC.
DCC Decoders come with CV03 and CV04 values set to zero
To control the Acceleration speed ( the time the train takes to reach crusing line speed ) is SET by CV 03. The engines Deceleration rate is set by CV04 the higher you set the value of CV04 the longer the engine will take to slow to a stop. Start with a CV04 setting of about 3 or 4 and a CV03 setting of say 4 Keep changing the values one number at a time so the engine won't run out of stoping room or crash into a forwared train. See page 129 of the Digitrax's Big Book of DCC. This will show you how to set up a braking track section that will cause a DCC equipped locomotive to stop automatically.
The trick here is to wire a relay to control track feeds, detector sections, and Siginal lights, to stop a train in a braking section.. It is best to read the Big book of DCC for the hookup and the wiring. If you don't have the big book of DCC, get it. It's a must have.

Good Luck,

[davekelly]

I'm not sure that reducing the voltage to the track would work as it is my understanding that DCC needs full voltage to the decoder and the decoder decreases the voltage to the motor.

[Anonymous]

See, I was thinking something actually along those lines for DC would work, but I want to run DCC, and dont' really want to combine the two on the same layout due to all the headaches that might cause. However I do like the 'kill power to that section of track' idea. Only if there was some kind of 'on/off' that could be stepped down gradually, to simulate momentum, and then back up to full track power... Of course, I don't know how a DCC decoder would react to a gradual drop in voltage on the system. I don't think it would work like DC would. There would have to be some sort of hardwired interface that could read the signal aspect and then directly control the loco(s) on the mainline train accordingly. I can see where that would involve a computer. But if there was no harm in gradually stepping down track voltage to a particular block until the loco just didn't have enough voltage to operate DCC, in other words, set the loco's speed at a constant, scale 40mph, and then essentially manipulate the voltage like you would in DC, in the blocks you wi***o stop and start the train. I'll have to research how a DCC decoder operates on different voltages before I fry any decoders though. lol Keep the ideas coming, I'm starting to get a clearer picture of exactly what I want to do.

[davekelly]

Seems to me that you can do this without a computer. This might be a little Rube Goldberg (or Mousetrapish - what a cool game!), but I think it could work. Please try not to laugh too hard when reading this.

First, you would have to have some sort of detection device on the industrial track on either side of the crossing. IR, photosensitive, whatever. As long as either was covered, a relay would be held in one position. This would operate something like a servo (with microswitches to limit the amount of turn) that would turn the dial of a DC controller with momentum on (don't know how this would work with DCC as I don't run DCC yet). When the detectors are both reading nothing, the relay would go to the other position, thus sending the servo the other way turning and in turn turning the dial the other way. I guess this would work also with DCC by having the servo the speed control dial or slide (DCC has momentum right? I'm not sure).
Like I said, pretty complicated from a mechanical standpoint, put I think it would work.

Perhaps one of circuitron's many little "black boxes" could be modified to protect the crossing. Not sure what you could use for the slow start and stop thing.

[MisterBeasley]

The hard part is the slowdown and speedup. If you can live with just killing the power to the mains a couple of feet on either side of the crossings, then it's really much simpler. As an "operational" thing, it's not as good as you'd like, but as a "fail-safe" whose primary purpose is to keep your trains in good condition, it does the job.

[Anonymous]

That sounds feasible in theory. By all means if you get so far as to actually have it operating, please post up when you do! Probably what I'll do, is wire up for a fairly simple DCC system like Atlas's DCC to get the trains running and my wiring infrastructure in place, and once I figure out how it's done, switch over gradually to a more complex system like the digitrax system.

[ereimer]

i've been doing a bit of reading about this type of operation since it's what i hope to have eventually .

1) i'm pretty sure it's possible
2) it's going to require a computer

assuming the computer is controlling 1 or more trains , and that computer controlled trains will only be run on the mainline (i suppose you could setup the software to go off the main , maybe even do some switching but that's way beyond what i'm interested in and i haven't researched that at all) ...

the track will need to be divided into 'blocks' , 1 block for each location where there is a possibilty of the mainline being occupied , plus at least 1 block on either side of that area (to give the computer controlled train somewhere to stop) . this will require something like the digitrax BDL168

if you want signals as well that will require more hardware like the SE8C and the actual signal masts etc

then to control the trains you will need the computer and software , i think Winlok and Railroad & Co. will both work , there are probably other programs as well . also you'll need a DCC system capable of interfacing with the computer , and the hardware to make that connection . digitrax with it's loconet and the locobuffer II seem to be the obvious choice

so far this is all theory for me , hopefully somebody who has some practical knowledge will correct my mistakes !

[Anonymous]

Well, I haven't wired anything yet... actually still building the benchwork, but I'm trying to get all my ducks in a row before I get to that point. I'm going to be the sole operator of a 16x21' layout (my wife gave me the bonus room for my b-day. lol). The branchline will have a continuous loop on it as well (4x8 mini-layout) but it won't cross the main, so running that will be no problem hands off, but the 'occassional mainline train' coming through during switching manuevers is what I'm really wanting to simulate. If there's no way to wire it without a PC, I'll have my computer up there once I've got the tables built, so that's not a problem, but if there's still no feasible way to do it, what I'll do is just run the mainline train on a continuous loop while I switch, and then pause my switching when it comes through, as though I called the dispatcher for clearance to cross the track. That's probably the easiest method anyway, and it'll be more mentally challenging to remember to realign all the switches before the mainline traffic passes through. If anybody can think of a way to do it, lemme know. And yes, I'm going 100% DCC from the start.

[Anonymous]

I don't know how exactly you would go about this but i think it would need a PC hooked up. You are using DCC right? Wait a couple hours some more educated people will post.

[Anonymous]

I really dont think theres anyway to do it, though automated through traffic would be great for those ops session when theres only a handful of guys!

[Anonymous]

On my layout, I plan to have a continuous loop mainline with staging hidden under the layout. Most of my layout will consist of two large (3x14) industrial switching areas, and one branchline (4x11). I want to be able to start a mainline train that will continuously loop the layout while I'm switching, however, I have two crossover points that will need to be protected from oncoming mainline traffic. If, for some reason, I have a derailment or some other problem and the switcher traffic can't clear the main in time, I'd like to devise some sort of 'fail safe' where the mainline traffic will automatically slow to a stop at a red signal just before the industrial area, and then when the crossing is clear, it will automatically slowly speed back up to the desired speed and continue on the loop. I know there are block signalling devices out there that automatically detect traffic and set the signal to the correct aspect, but I'm really interested in an 'autopilot' approach to mainline traffic while i'm switching. I will also like to have hands on control of the mainline when I need it. Does anybody know how I could do this?