Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Signalling Systems

7 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    September 2004
  • From: Ontario, Canada
  • 95 posts
Signalling Systems
Posted by CMLewis on Wednesday, January 30, 2008 8:45 PM

Well done, Kevin, this is going to be a very useful forum.

I'm still in the benchwork/trackwork/scenery stages at various points around the layout, and have begun to think about signalling.  I have mentally divided the mainline into rough blocks, and have looked around the Internet at a few systems, but I'm not sure where to go next.  I have a few criteria:

- prototypical operation

- four to six mainline blocks, expandable

- plug and play would be nice, but building and programming is an option,

- DCC-compatible.

I know anything can be done for a price, but let's keep an eye on cost.

What's the next step?  Perhaps someone can turn this into a signalling primer for those of us who are wandering around in the dark.


  • Member since
    February 2005
  • From: Southwest US
  • 12,914 posts
Posted by tomikawaTT on Thursday, January 31, 2008 11:13 AM

Good morning, Chris,

The basic requirement is some form of occupancy detector for each signal block, which will detect current flow if a locomotive, lighted car (passenger, caboose, FRED) or resistor-equipped car is present - and convert that data into something that will drive a logic circuit (or a relay, for those of us who still use the brute force and ignorance approach.)  I haven't done any product research, but I recall there having been a number of detectors marketed over the years.

Some modelers are satisfied if the two ends of the train will activate the detector, while others want to detect every freight car (as the prototype is supposed to do.)  Some detectors could work on as little as a milliamp of current, but a layout with several hundred cars could easily add a significant load to the power supply if all of them are fitted with 4.7K resistors.

Such a system has one unprototypical feature.  A powered speeder will trip the block occupancy detector.  Prototype speeders have insulated wheels so they will NOT activate the signals.

Chuck (modeling Central Japan in September, 1964 - with ABS in the future)

  • Member since
    February 2002
  • From: Westchester NY
  • 1,745 posts
Posted by retsignalmtr on Friday, February 1, 2008 8:54 PM
i'm getting ready to install some signals on my n scale layout. i'm going to have about 10 blocks and around 16 signals. i just purchased at springfield a signal starter kit from dallee electronics. it comes with three current sensing detectors and a power supply. i plan on using them in conjunction with the atlas signal control boards. i'm still trying to figure out how to provide directional control for operating in both directions. to do what i want i may have to use other relays, pushbuttons and wiring. the detectors will work on dcc but my system will not be controlled by it. i'm a retired signal maintainer and have all my circuits already designed based on an analog system using relays but i think it will be simpler to use the atlas and dallee components and add things as needed.
  • Member since
    December 2002
  • From: US
  • 159 posts
Posted by tomytuna on Saturday, February 2, 2008 6:52 AM
hello all! Here's what we did...100% DCC..Purchased Atlas should NOT provide power from track to power the lights on signals...will kill the led's..what we did was take an older DC transformer and ran an additional feeder system under table with junction power strips at different locatations. run wire from DC supply to LIGHTS   but install detector on works..Tom
  • Member since
    January 2007
  • From: Eastern Shore Virginia
  • 3,290 posts
Posted by gandydancer19 on Sunday, February 10, 2008 2:50 PM

Hi Chris - and Others,

I am in the process of designing and installing a signaling system on our club layout (Digitrax), so I thought that I would share what we are doing and what parts we picked.  I am also going to be signaling my own home layout (NCE) in a different manner, so will explain some of that too.

Club & Digitrax -

1. We are building our own signals so that is going to save major bucks.

2. We have selected the Digitrax SE8C signal board as the primary board.  It will control 32 three light signal heads.  It is pricey.  With this board you can also control 8 tortoise switch machines and 8 detedtion blocks (with added hardware for the blocks).

3.  We are using the BDL168 detection board which will detect 16 blocks, also by Digitrax.

4.  You do need a computer and program to run it all on LocoNet. 

5.  If you add turnout control boards (DS64) you can now control everything.  You can also have individual panel or throttle control of turnouts.

Like I said, this is kind of pricey, but once the stuff is installed and your program is set up, you can run your trains prototypically.  You may even be able to set up a scheduled train to start on it's own and traverse the layout, obeying all signals.  I call this the "Open House" mode.  Now, if you don't have a Digitrax system, you can still use the Digitrax boards with a computer on LocoNet.  LocoNet is like a computer network where all boards listen and talk to the computer just like a LAN network.  It's just not connected to the track (except for the block detection).  (Did I say that I don't like the Digitrax DCC system except for LocoNet?)

Home & NCE -

At home, I have chosen the CTI Electronics system. 

1. This is NOT linked to the track either. (Except through detection)  

2.  They also have different modules to control different devices.

3.  The CTI boards are also linked together by a network and cabling.  They use a four conductor phone line, and you must use a computer and program also. 

4.  CTI can be used with various DCC systems that can be hooked to a computer, to control your trains if you desire.  (Requires two computer connections, one for your DCC system and one for the CTI system.)

5.  I am also building my own signals to save bucks.

6.  You can use the CTI system on DC layouts also. (That's where I started with it.)

I chose this system before I knew about the Digitrax SE8C signal board, and even before it was available.  It looks like both systems are going to cost about the same in hardware expense once the system is complete.  I think the CTI system is more versitle, but you have to use their program and write your own code, although I think I heard where they are working on a GUI program.  The turnout control boards are not programmable as to being able to change the type of turnout machines they will operate.  That is, if you have twin-coil machines, you buy the board for them.  If you have tortoise machines, you buy the board for them.  The cost of the individual boards is lower with CTI, so you could start smaller and grow the system as you need too. 

With either the Digitrax or CTI systems, you can change things around as your layout changes.  If you get tied into a hardware based system only, and your layout changes, you move, or start another layout, you may not be able to reuse all of the Atlas or other vendors hardware based stuff, even though it may be cheaper to start with.

Hope this helps,



The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) at home, and N scale at the Club.

  • Member since
    March 2003
  • From: Scottsdale, AZ
  • 723 posts
Posted by BigRusty on Monday, February 11, 2008 5:59 PM

Back in the 60s, I used the NMRA detector. I had 9 blocks. I used 3 pdt relays. One set of contacts was used to kill power to about 18 inches of track prior to a signal to prevent a train from overrunning it. The other two sets routed power to the 3 light signals, with one set voiding the following green and lighting the yellow after a red signal. It worked beautifully and never gave me any problems. The problem with it, as with any analong system, is that it has to be hard wired. I would have had to add many more relays in order to protect the turnouts at sidings, etc. Not an option.

With that experience behind me, I learned to love signalling. Watching the signal lights changing all over the layout as trains progressed was very satisfying to me. I would never be without it.

That said, I have looked into the CTI system, which, being a digital  system, is totally computer operated. Making changes, is just a matter of reprogrammig the system. It will function in either direction, control interlockings and signalling at sidings and crossovers or whatever your requirements are. As soon as I get my garage 8 x 18 douible track test loop built I will get a CTI system. Using it now will give me a big leg up when I get to building my permanent layout.

There is really no other practical way to do this in this Hi Tech era.

Modeling the New Haven Railroad in the transition era
  • Member since
    January 2005
  • From: SE Pennsylvania
  • 12 posts
Posted by wawa on Tuesday, February 12, 2008 11:36 AM
Try looking at TDP & Associates.  They have a ABS Master that is a stand alone signaling system that works with any kind of signals.
  • Member since
    February 2007
  • 5 posts
Posted by cribs1 on Thursday, February 28, 2008 12:04 PM

Try looking at the web site.  They have mostly o-scale, but carry the Atlas ho and n scale signals also.

The signal system will work with all scales, DC or DCC, and will give both ABS and APB signalling.  The modular system make it adaptable to almost any layout and the cost of the pcbs is very reasonable.  Check out the Track Configuration Library on the web site.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

Search the Community

Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!