ABS Signals For Your Model Railroad (287)

Signals add a lot of interest to your model railroad, especially if they actually work just like on a prototype railroad. In this video I'll show you how to install a simple ABS signaling system on a model railroad and also go over the one I use on my Piedmont Southern layout.
Model Railroader Archive
www.trains.com/mrr/magazine/a...
Chapters
0:00 Intro
1:25 Warley Reminder
2:13 Unintended Consequences
3:52 ABS System Background
6:35 Model ABS System Demonstration
9:37 ABS Articles
12:36 ABS 3 Color Signal Circuit Article
13:15 ABS Searchlight Signal Article
13:52 Prototype And Model Installation
16:30 Detailed Installation
17:59 Wrap

[@lucquenneville875]

Hey, Mrs Puckett, I don't want to lose you. Your videos are very instructive!

[@tonymoore8515]

Larry I am enjoying your videos as I am starting a new HO Layout. Your signalling video is a great video.

[@richardw5507]

Looking forward to your uk channel Larry

[@andrewstevenson5449]

Thanks Larry. Adding a comment to keep YT happy. Sorry to hear they've tried to sabotage you!

[@TheDCCGuy]

I appreciate that

[@michaelsmodelrailroading7665]

Thanks for this very informative video. Functioning signals significantly improve the operational realism on a layout. Your videos take a lot of the mystery out of signaling, and make installing a system an achievable goal. Thanks for taking the time and effort to address this topic so thoroughly.

[@peterkrause5187]

Absolutely (pardon the pun!) What I have been looking for! Thank you. Cannot wait for next weeks episode for the circuit description!

[@TheDCCGuy]

Excellent!

[@MrAsBBB]

This is Alex from London. I for one will be looking at both channels. I just find it all totally fascinating. Thanks for everything you do.

[@1952TonyC]

Churchill was spot on when commenting on two nations divided by a common language. ABS in US = Automatic Block Signalling. ABS in UK= Absolute Block Signalling which is pretty much the exact opposite of automatic!

[@flyboy2610]

And here I thought ABS was a type of plastic...

[@RonDennisMum]

Enjoy watching you from the UK Larry!

[@SD45-ET44AC]

You ask people to subscribe by clicking the “red subscribe button.” My buttons are all white & yes I’m subscribed. I love your past episodes and they are filled with great & useful info. Thank you for all you do.

[@TheDCCGuy]

Well the button image that I include at the bottom right of your screen is red with white “Subscribe” lettering so if all you see is white then something else is happening!

[@jonathanlake6053]

I am subscribing to the new UK channel,thanks Larry.

[@jhoodfysh]

Hi Larry, you are correct, sadly, KZbin is a very harsh mistress. That being said, please keep going. Although I do not run Brit rail, I did subscribe, just to make sure it continues. I always learn something from your content. I really appreciate the detail you provide in your videos. Your explanation and reference to sources was excellent. I laughed when you said at the beginning, "as long as they obey" the signal. I think there might be a story lurking there somewhere. I am looking forward to seeing the next episode.

[@alangaul9608]

Great material Larry

[@barry3573]

Thank you for another good signal video. It's given me several ideas for my layout.

[@pinball1968]

I was really hoping this video was going to talk about block detectors and how those worked. I know there are different types, and such, but wanted to see which you used and what the limitations would be (overhead lights for photocells, IR detector limitations, etc.). Hopefully the next part will cover that.

[@TheDCCGuy]

I might have hit on some of that in video #217 and I will do a little on Friday but it really would require a separate video just on detectors.

[@pinball1968]

@@TheDCCGuy That has always been my biggest hang up with signals for model railroading. We have constraints with voltage running through our rails that the self-propelled prototypes don't have to mess with. Even the DC driven light rail can use AC for track circuits. But with the advent of DCC, we lose the ability to control track circuits with AC, as it's in use by the DCC systems. But I'd like to see what you (and others use) use, and what kind of failsafe to Red are built in (Atlas fails to green, so I don't like those). I'll probably just stick with Photocell, despite the drawbacks.

[@davidcrouch5272]

Another very informative video I will be for sure signing up for your UK channel

[@theplumber33]

I've been watching you UK Mondays. Great video on signals. Keep em coming brother

[@TheEMD710]

Finally..... I am starting to understand... I think my layout is too small at the moment as my second level is not built yet. But this was very helpful. Train length will be a problem for me, coal trains are long.... I need to plan for that.

[@JWitchard]

I will definitely be subscribing to your UK channel. 😊👍

[@elsdp-4560]

Thank you for sharing. Very much going to enjoy this series.👍👀

[@derrickpensom5429]

Great video as normal. In the UK there is a company called Train Tecn that males DCC sensor signals. They work without the need for additional circuit boards

[@TheDCCGuy]

They have some interesting stuff. However at about £45 or $50 for a 3 aspect signal I think I’ll stick with mine which cost me about $30 even with the NCE BD-20 detector. The good thing about them is they come ready to install.

[@mikeseba7817]

Thanks Larry for the information.

[@markwakeley3835]

Wonderful video and I'm looking forward to the UK version. I learn things from them as well. Enjoy the train show. Cheers Mate

[@peterjhillier7659]

Thanks Larry, another great how to Video, looking forward to the second Part. Keep safe.

[@TheDCCGuy]

Glad you enjoyed it

[@rjl110919581]

THANK YOU FOR THE VIDEO

[@johnodonoghue7381]

Great video informative too

[@williamlegg6542]

In my experience from my time on the railroad yellow or approach is “proceed at preparing to stop at the next signal”. A green over yellow would indicate “proceed thru diverging route preparing to stop at the next signal.” A restricting signal would be a red over a mile marker on the mast of the signal. A stop is just that. Red. Usually at control points of a siding or interlocker. Restricted speed is usually used within yard limits which by definition is not the limits of a rail yard. Restricted speed is used on the mainline from time to time. For rules compliance a train crew can be banner checked for restricted speed compliance either by operating within yard limits, getting permission from the dispatcher to pass a stop indication, or passing a restricted indication (red over number plate). If a trainmaster were to banner check a crew on an approach to a stop, that manager would then look silly because he does not know the rules he is trying to enforce.

[@TheDCCGuy]

This is a simplification of the prototype signals with only a single target per mast so no green over yellow, etc. although for someone wanting that it could possibly be done with Scerb’s circuit. For model railroads I prefer to slow engineers down as most have a heavy foot on the throttle so yellow on the PS will mean proceed at reduced speed.

[@williamlegg6542]

@@TheDCCGuy I understand what you are saying. From the prototype perspective if a crew were coming around a bend at 60 MPH and 1/2 mile was a restricting signal, that crew would never get that speed down 15 MPH or less. They would pass that signal already violating restricted speed. I do appreciate your simplicity and I’ll consider using something like you’ve shown in the video.

[@TheDCCGuy]

I dug out my notes on SR speeds and have the following: Limited-NTE 45 MPH Medium-NTE 30 MPH Reduced-Proceed prepared to stop short of train Restricted-Proceed prepared to stop short of train NTE 15 MPH Slow-NTE 15 MPH Yard-Speed permitting stopping within 1/2 range of vision

[@timwashington8711]

Larry first of all I just want to say that your videos has really helped me out tremendously. Very detailed and informative. Keep up the great work! My question to you is in reference to video #168. What type is the barrel plug connector were you using with that 16 volt power supply. I would appreciate any info. You could give me on that. Thanks! Larry.

[@samuelmacbride2031]

Hi Larry again, What i meant was what were the signal board manufacturer… Thans

[@TheDCCGuy]

Me

[@samuelmacbride2031]

Hi Larry , Enjoy your videos immensely! Was wondering what the brand of detector you were using with the bd20’s. Thanks

[@TheDCCGuy]

The BD20s are the detector. We’ll look at the signal logic boards next friday.

[@CobraChamp]

another great video Larry! I am going to use Searchlight signals. Where is the best place to find a simple pcb layout like you've done for your layouts ABS signaling? Alternatively, are you aware of a commercially made product for Searchlight signals?

[@TheDCCGuy]

As I said in the video Jeff Scherbs 2nd article provided a schematic for searchlight signals. You’d need to dig up the article and then create your own board as I described in the video. Or do a internet search for signals to find the companies that offer them ready made, and there are several, I just don’t have that info.

[@Mark_W_L]

Very interesting Larry. I'm in the process of implementing CTC with a JMRI control panel and Signalist SC1 boards controlling the signals - a lot more expensive than your ABS boards. You said that an Approach aspect will require the engineer to reduce to Restricted speed. The NORAC rule book (11th Edition) says reduce to Medium. Was the Southern more cautious or did it have short blocks?

[@TheDCCGuy]

On the PS restricted speed will be half speed. I’ll have to check my SR rule book for the exact interpretation.

[@theknickerbocker5808]

Speed is kinda important. The big thing on an approach signal is being able to stop at the next signal if it is all red. Restricted speed in the application of professional railroading is more a method of operation that a speed. The speed or speeds mentioned in the rule are caps.

[@jovetj]

This aspect of the video kinda made me... angry. An _Approach_ signal should not require Restricted Speed. A _Restricting_ or _Redistricted Proceed_ or _Stop and Proceed_ signal would.

[@sailingspokojny9809]

Larry, after watching your videos on DCC throttles etc., I recently purchased the NCS power cab starter kit. I also picked up a DB5 Booster but when I got them home, it looks like I should have purchased an SB5 first. Should I take to the DB5 back and get the SB5?

[@TheDCCGuy]

I think I would have gone with the SB5 as it is amore direct upgrade path for the PowerCab.

[@sailingspokojny9809]

@@TheDCCGuy Thank you for the information. I will see if they will let me exchange the SB5.

[@samuelmacbride2031]

Hi Larry, when using the bd-20 in a section of block that has for example three feeders.. must they all be tied together coming thru the bd-20 for it to work correctly ? According to nce manual that is how the bd-20 was designed to work.If thats the case ,seems like a lot of rewiring,or did i misunderstand that? thanks for your videos!

[@TheDCCGuy]

The BD-20 must be placed at a point before the first feeder in order to reliably detect occupancy. It also needs to be before and twisted wires and things like snubbers or other devices such as frog juicers that draw track power can cause false detects. However the BD-20 has an option to add a resistor which reduces its sensitivity. I will take a look at that and another method when I show how to install these on the layout.

[@samuelmacbride2031]

Hi Larry, is there alternative to the bd-20’s for the signaling circuit that youve built? No one seems to have them…..

[@TheDCCGuy]

@@samuelmacbride2031 Check out the DCC Concepts LM-iD. They are very similar to the BD-20. I used them in my automated reverse loop video.

[@samuelmacbride2031]

Hi Larry, On your wiring diagram for installing the abs lighting,would the last yellow out loop back to the first yellow in?

[@JSGregg]

Interesting circuit - what happens if you ground out two or more detect pins at the same time?

[@TheDCCGuy]

Yes you can ground some of the outputs to force a color change. That is shown in the diagram I showed for the way to wire it to the layout.

[@JSGregg]

@@TheDCCGuy Yeah I built the circuit in Falstad (online circuit simulator) and noticed that - pretty cool that it can do all of that with so few components. Interestingly, according to the simulator, there is a small amount of current flowing through the green LED when red is on - anywhere between 1 - 4mA. Is this visible in reality? I didn't notice that in your demonstration. Also, you may be able to remove the diode completely or just bridge it out. I could be wrong, but it doesn't appear to be doing anything in the circuit. This inspired me to build my own circuit that builds upon this concept. Thanks, Larry!

[@barneyrubble1964]

Have you got a link to the UK channel?

[@TheDCCGuy]

Try @ukmodelrailways

[@barneyrubble1964]

@@TheDCCGuy Thanks, already subscribed Looking forward to part 2 of the signals, want to see if I can use it on a rather small 2x4 009 layout.

[@whitemaniagaming6942]

Would it be possible to get a video on painting trains for beginners?

[@TheDCCGuy]

I have a handful of unpainted models to do and when I get to them I will do a video of it. Can’t say how soon but probably this winter.

[@whitemaniagaming6942]

@@TheDCCGuy Sweet! I look forward to it.

[@robertpetit57]

Larry, can you add a link to the company that made your boards please.

[@TheDCCGuy]

Watch the next video and read the DESCRIPTION!

[@bearuffus]

What constitutes a "block?"

[@TheDCCGuy]

Any isolated section of track. I described these in the video and even showed a diagram, did you skip tat section?

[@jovetj]

A block is the section of track between and protected by block signals.

[@GooseinTheCabooseProductions]

Nice larry. Doesn't quite apply to me since I'm going for a dispatcher control 50 style CTC signaling system, using mostly dick Bronson's components and a few Digitrax components.

[@TheDCCGuy]

Yes, if I were modeling the Southern a decade later I would be using CTC but in 1957 it was still ABS.

[@GooseinTheCabooseProductions]

@@TheDCCGuy when did Southern switch to CTC? Ithought it was sometime in them early 60's. I went with the CTC because I wanted it and it just seems to fit with a 1954 coal hauler.

[@TheDCCGuy]

I think it was a phased roll in and it did not get to my section until the mid-1960s. Once it was in place they started removing alternating sections of double trackage and bridges accordingly. Signal towers, such as the one at Charlottesville, were eliminated and other changes as required were done. So it took a few years to complete the entire Atlanta to Washington DC mainline. I have read that CTC operations were so efficient they found they could actually run more trains on alternating single/double track than on the original double track line. Plus by eliminating infrastructure they were able to reduce taxes.

[@mach37]

Off Thread: This "complication" prompts me to ask "Once I have my 4 x 8 DCC layout completed - 12 turnouts, mixing Atlas and Kato turnouts - can I use a simple toggle-switch between DCC and a DC operation? Do I need to bypass the NCE PSXX circuit breaker when using the DC controller? I assume "yes." Any other considerations for the turnouts; I have left the Katos at Power Routing; should I change that? Frog Juicers? You only need answer if you know off the top of your head, I'll do my own research if you would have to resort to that. I'll not be offended if you say "do your own research."

[@TheDCCGuy]

Yes, you can use a DPDT switch to go between DC and DCC and I showed how in my wiring book and in a MR article. As for things like Frog Juicers and PSXX you will need a way to isolate them as they are not DC compatible. If you can avoid it I no longer recommend Frog Juicers, see my recent video on that.

[@mach37]

@@TheDCCGuy Thanks for confirming that PSXX and Frog Juicers must be bypassed.

[@jovetj]

Ummm... Approach (yellow) signals don't typically invoke a requirement for Restricted Speed, which has very specific meanings on railroads.

[@TheDCCGuy]

Remember the standard rule “it’s my railroad and I make the rules”

[@jovetj]

@@TheDCCGuy Well, I can't argue with that!

[@charleswalsh9895]

You tube is messing with your following. Every time I log into your KZbin station it no longer has me subscribing to your KZbin blog

[@billyholiday4947]

A lot of unnecessary gibberish in your videos! Short and sweet is the key!

[@TheDCCGuy]

Glad you like them!