It's really pretty much exactly liek the real thing. You need signals, of course. You need track circuits - those are the block detectors. And you need the logic, either configured in a device like the SIGM20, or using a PC interfaced to the layout. And something to drive the signals. The SIGM20 drives the signals and has the logic - check and see if it can do PRR-style position light signals though. The SE8C from Digitrax is just the driver for the signals, the logic as to which signal to set to which indication based on which blocks are occupied is handled by a computer, using either JMRI which is free or RRR&Co which is not.
--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 understand the theory behind real world signals and why they work, and I have a general idea of placing, I just don't understand the equipment and material i need to set up a HO scale version. Thanks, mike
Take a look at this arrangement.
Chris van der Heide
My Algoma Central Railway Modeling Blog
Mike, you really have to go out and learn how and why signals are located and how they work, what the indications mean and why.
If you're going to set up a signal system, you need to know how the system works in order to plan where your block boundaries are and where your signals are placed and what types. Then you have to figure out the logic yourself in order to make your signals show the proper indications, since there's nothing "out of the box" that can simply figure that out. Every layout and situation is different, and designing a signal system is actually a fairly complicated undertaking. It's certainly doable but you need to understand how and why the system works or your signals will have no basis in reality, which I assume is the goal here?
Your simple line diagram in the last post certainly doesn't actually show what you'd need for a workable system. What you need to do, is figure out your control points, break the mainlines down into individual blocks and figure out where the signals need to be placed. Each track block would require a current detector (which of course only detects an engine or other equipment drawing power - you'd need resistor wheelsets to detect freight rolling stock). Then based on the block occupancies, and positions of mainline switches, you determine what the signals should be displaying. If you're trying to do a workable CTC system, then the signal indications are additionally based on how the dispatcher is clearing trains through, which means you need to work up a CTC panel on the computer as well.
Ok so would this be what I need ? Thanks, Mike
You basically have a 4x8 layout. The placement of the detectors have more to do with the room and where people see them than anything else. Say you have 2 signals. You would need 4 detectors or sensors. At each signal there is a sensor right next to it. A train crosses a signal. the signal turns red. The train then crosses the next signal. The second signal turns red and the first signal stays red. When the end of train leaves the second signal the first one turns yellow. When the end of train leaves the third sensor first turns green. This is why you need the extra sensors. It takes 2 past the last signal to make the last one green.
Springfield PA
Ok Here is my layout in a nutshell, with a quick 15 min sketch. Could you please highlight where I would need to mount a block detector? Thanks Mike
You will likely need more block detectors than are provided for on the SE8C - and the SE8C doesn;t have the actual detectors, just inputs for them. The block detector device itself woudl be the BD4, which handles 4 blocks. 2 of these can be connected to each SE8C. For additional blocks you can either connect BD4's to DS64 stationary decoders or use a BDL168 which has 16 block detectors in it.
If you want the signals to actually 'tumble down' as a train proceeds, and have 3 or more aspects, then you do need to use detectors on everything.
The data flow with Digitrax Loconet components is: Block detector senses train. If connected to SE8C, the SE8C sends a message on Loconet to the computer. If a BDL168, it sends a signal on Loconet. The computer software interprets which block was just entered, or vacated (you have to program this stuff in, it's not automatic) and sends a signal to the SE8C to set a specific signal to red, or green, or yellow (or display the proper position lights in your case).
I cannot stress enough to read the various signalling technotes on teh Digitrax site to get an idea of how this all works together. There is alternative ahrdware that works the same way as the Digitrax components, such as the RR-CirKits Tower Control. There are also complete standalone systems that do not connect to the Loconet and use their own interconnections - the advantage being they work with other brands of DCC as well as, in many cases, DC. The beauty of an all-Loconet system is that you probably already have Loconet cables run to various parts of the layout, to support UP panels to plug throttles in (unless your layout is very small and you only operate from the Zephyr console), so instead of runnign yet another set of wires, you use the ones that are already there.
I know it will be expensive and quite a project, but explain please, how does this work.
Ok, so I need block detectors, do I need them for every track?
Now, the block detectors run into the SE8C, which will recieve the information from the block detectors, which will then send it to a computer which will tell the SE8C what to tell each signal to display?
Am I correct? Thanks, Mike
if you check out www.trainspeed.com you'll see a couple of examples, including block signaling and crossing signals. The actual signals have varying prices depending on the quality you want. Mine are mostly from Tomar and are brass.
Check the Application Note section on the Digitrax web site, there is a detailed document that shows how to hook Pennsy position light signals to the SE8C signal controller.
This is no minor undertaking - you will also need block detectors. If you use the SE8C you'll need a computer interface (PR3 or Locobuffer) as the SE8C is a 'dumb' device and doesn't contain any logic to set a given signal indication based on the input of a block detector. The SE8C is just a driver board for 32 signal heads (and 8 stall motor turnout motors).
I don;t want to discourage you, but settign up an actual workign signal system that provides proper indications (and not just red when the turnout is thrown one way and green when it's the other) is not soemthign you can just buy for X dollars, open the packages, and plug in the wires and boom it works. Nor is it inexpensive - some say it's the electronics but the signals themselves, to buy them ready made, I'm goign to guess about $30 each for a single head.
There are other controller boards besides the SE8C, some of which ave the logic built in - so you can program it such that signal 1 is red if block 1 is occupied, yellow if block 2 is occupied, etc. The expensive part is still all the signal heads.
I have a layout that is a 4x8 with a yard extension, in HO scale. I am modeling the PRR. I use a digitrax Zypher for my command control. I have three questions.
1. What all do I need. I need a detailed list, I want to use PRR postion lights.
2.Where can I get all of this, (Manufacturers?)
3.Where do I place my signals?
Thanks, Mike