Block Detection For Your Model Railroad (269)

[@alanmusicman3385]

On a layout of any size (or a layout with sections that are hard to see) measures like block detection and automatic train ID (using RFID, NFC tags etc) have to be very handy additions. Good to see you using Wago lever connectors - they are a real boon and seem to be usable with most gauges of wire - even very thin ones. Always amazes me when I see some modellers still using the old choc block screw terminals for new work. Lever connectors in a frame, or even superglued on to woodwork are so much easier.

[@TheDCCGuy]

Yes, I like them much better than the push type since it is very easy to insert even small stranded wires.

[@alanmusicman3385]

@@TheDCCGuy Yep agreed. Not sure if I have been unlucky or not, but I have tried several types of push fit quick connectors but they are never very secure.,

[@mlkesimmons758]

Very clear explanation. This will be a great way to show occupancy on a manual CTC panel.

[@ronduz1281]

Great video Larry👍👍👍 Great explanation and demonstration on how it works

[@chuckholsclaw6829]

Thank you Larry, I'm not quite ready for detection but I do find your videos helpful. I installed an sb5 smart booster on my layout, made my own cables for my utp panels and divided my layout into four power districts. Chuck

[@TheDCCGuy]

Great job

[@dundasjunctionmodelr.r-jam8267]

Larry , great video, need a drawing showing me how you did this , helix looks great

[@thomasgrassi8817]

Larry Nice overview of BD20. I use BD02 on my Layout I have about 100 Blocks now. I use NCE AIU-01 to connect all my BD20's to I use JMRI and the signal from the NCE-AIU-01 send to JMRI Panel and the track turns RED when occupied Also Have my entire railroad signaled with the help of the BD20's looking forward to more of your well informed videos

[@MrAsBBB]

Extremely well explained sir, You obviously love your subject and are a true expert. I really enjoy your videos. A big thumbs up 👍 from Norfolk, England.

[@geomodelrailroader]

also if you are installing a block you need to place the insulators in three locations or you will get reds when the detector is activated. the first one goes behind the switch the frogs are isolated the rail is not the first one goes here, the second one goes on the inside rail in the middle of the block that way it only shows your train when the block is occupied, and the third goes behind the switch on the other end of the block that way you have three sections. If you have double signals entering a siding YOU MUST INSILATE THE INSIDE RAILS LEADING INTO THE SWICHPOINTS! also every intermediate signal needs to be wired to the YIN jack on the signal control board. Intermediate signals only display Yellow and Green once a train is out of a previous block and Red when the block is occupied. If you have an industry in dark territory you must protect the main with a single light signal and have a selector plate to set this signal to Red to replicate electronic locks.

[@greatnorthernrailwaytother4711]

Another informative video. Thanks Larry. Regards Peter.

[@mikeseba7817]

Another useful video. Thanks for sharing!

[@bbf15c]

Have you had any problems with track staying in gauge at the gaps? Just curious since you're only using screws and washers to anchor track, which I'm in the middle of doing now too. Just figured I see about your experience before I start cutting. Thank you for your videos!

[@TheDCCGuy]

So far none. I think since the track is bent to shape well before cutting the gaps it retains the curvature quite well. If it ever does tend to bend inward then a tweak with needle nose pliers will get it back on shape. Similar to adjusting the points of a turnout.

[@rjl110919581]

thank you for sharing detailing video as great watching wait see the next step with bd20 been used as look better job nec bd20 from the first lot made in 1997

[@farmerdave7965]

I love BD 20s but they only work with AC (DCC). Will not work with DC.

[@elsdp-4560]

Thank you for sharing.👍👀

[@trevorsmith2152]

Great demonstration Larry thank you.

[@philipwells9498]

Larry, I know that it was a much earlier video in which you discussed making Loconet RJ 12 cables. I need to make some and cannot find the materials and crimper at AllElectronics. Could you guide me to where I could find the materials and part numbers? Thank you, pw.

[@TheDCCGuy]

See video #38, parts numbers are in the description.

[@TheEMD710]

Clear!!! Finally.... I get it ...

[@luke_atthat]

Really well explained. Thank you.

[@johnschutt9187]

You may want to put the maker and model number of the parts that you're talking about in the description under the video. And maybe the cost?

[@TheDCCGuy]

I usually do that except when I mention the manufacturer and model name/number in the video as I did in this one!

[@68Jaguar420G]

It frustrates the blazes out of me when OEMs recommend that we use 14 awg (or in some cases 12 awg) bus wires but don't build their components so they are compatible with this size bus wire! Here you are inserting the BD20 into the bus wire (the detector wire going through the toroid is essentially a series component in the bus wire) but you have to reduce the wire size so it can be looped through the toroid itself. Sure you have kept the 18 awg segment to a short length to minimize voltage drop but it largely negates the intent of a large gauge bus wire and also has a much lower current capacity than the bus wire itself. It also means grouping the detectors in a common but more remote location is a lot more problematic. It is the same situation with the NCE snubbers, 14 awg bus wires are recommended but the input wire screw terminals won't take a wire larger than 18 awg and even that size is tough to fit. This is an area where the industry needs to have much better internal consistency. Perhaps an NMRA RP is required? .. Rant over, otherwise nicely explained and demonstrated Larry.

[@TheDCCGuy]

I think that is dependent on the size of the hole in the current sensing transformer and they have to use what the electronics industry makes. Unfortunately the demand fir these parts in our hobby would not be enough to custom design a part just for this purpose so we get what they make. However the use of a smaller diameter wire is not a concern on this application as long as you keep it as short as possible to do the job.

[@dundasjunctionmodelr.r-jam8267]

Larry I found the video thanks

[@davidperrott4502]

how do you keep your curve constant through the plastic rail joiner since the joiner is on a curved joint.

[@TheDCCGuy]

I had installed the track using metal rail joiners soldered together and glued them down using construction adhesive. Afterwards I cut the rail gaps using a cutting disk in a Dremel tool.

[@davidperrott4502]

@@TheDCCGuy Thanks, I thought you may have had a way I had not thought of, knew there was more to it than just adding a plastic joiner. I did similar but used circuit board across both rails then cut the rail.

[@BillMasters-gz3zr]

My BD20 relay output is flickering when the loco is in the detected block. Is this something I can fix by putting your Keep Alive design on the component that's attached to my relay output or am I just doing something else wrong that I need to fix?

[@BillMasters-gz3zr]

Never mind, I figured it out. I need to add two .3 farad 2.7v super caps to my Light-It decoder as per the NCE manual.

[@TheDCCGuy]

Happy to hear you figured it out.

[@MilwaukeeF40C]

Let's say both end axles on every car have resistors. Is that too much current for the signal circuit? I want realistic signaling whether one axle enters a block or an entire train with any combination of cars without worrying that the first and last cars are able to trip the circuit.

[@UTtrainsignalmodeler]

A few things to keep in mind here. If you run like most folk do, they still use cabooses, and as such, those should have detected axles on both ends of all cabooses. If you're running more modern operations, without cabooses, then detection of both end axles of each car would be more realistic, but I'll stop short (no pun intended) of saying it's required. Most operating scenarios won't get so detailed that the length of a car will factor into a "major incident" occurring. For example, if you're running trains and there's a potential that two cars may be longer than a turnout block (commonly called an OS in industry), either lengthen the block or add some delay turn-off to the detected block. If you're determined to run two detecting axles on each car, I'd worry more about my pocketbook than over-current on the layout, if you're buying pre-made detected wheelers. If we do some simple arithmetic... Even though DCC is technically AC, I'll use Ohm's law based on DC for simplicity and ease of understanding - it'll get us close enough... If we assume 10kΩ per detected axles, and just for purposes of our discussion we say we have 30 cars for our train, some quick division gives us the first following math: 10,000 Ω per axle / 2 axles = 5,000 Ω for each car. Using 5,000 Ω per car, we plug that into Ohm's law and we get the following: 5,000 Ω per car / 30 cars = 166.6 Ω for the total resistance of that train, minus the engines. 14 volts track power (nominal DCC power for HO) / 166.6 Ω for the train's axles = 0.084 Amperes, or 84 milliamps. This is slightly more than a single 50 mA grain-of-rice bulb. Unless you start getting into hundreds of cars with this scenario, all being driven from a single booster or command station and circuit breaker, the currents consumed by the detected wheelsets are negligible. Three incandescent lit cabooses would be equivalent to nearly three trains worth of cars. I say detect away.... And have fun! Detection is fun and the next logical step is block signal control... That can be a hoot as well. Happy trains!

[@donaldshroyer8633]

While this was a thorough and informative vid, aren't there more modern technologies that signal train occupancy without need for electrical blocks, and using considerably less wiring?

[@TheDCCGuy]

DCC Concepts has their ESP wireless system that uses wireless feedback modules attached to the detectors which in turn can be attached to wireless interface modules to control LEDs on a control or display panel. But in a small situation like this it is like going after flies with a canon. Sometimes a simple old flyswatter still does the job better and is a lot cheaper in the long run-there is a price for technology. If you find a better way let me know.

[@donaldshroyer8633]

While I don't want to push a product I don't use and have no experience with, I was thinking of the Modern Train Technology Precision Detector. That hooked to a power supply and an LED output seems much simpler.

[@TheDCCGuy]

The MTTPD is an optical detector which means you only know when a train or loco or car passes a certain location. These work great if all you want to do is activate a signal or a crossing gate. I showed a version of this in another video (217-218) I did to control signals at my Rockfish River crossing. These could have been used in this situation but once a train passed the detector the light on the panel would go out so you would need more of them to cover the same space and you still will need the track feeders and wires for powering the track and the fiber cables to go from the detector interfaces to the display panel. So how are the MTTPD devices simpler or better? If you want actual block occupancy these are problematic as you would need to link them to a computer to track when a train enters and leaves the block. And that requires a program capable of doing that, plus the wires and interface module for getting the info to the computer, and wires to the LEDs, and fiber cables, etc. The block occupancy detector method I used avoids the computer link and programming and makes it simpler in my opinion and does a better job with fewer detectors.

[@MilwaukeeF40C]

Real signals use simple rail circuits just like this. Yes wiring is tedious. But it will be reliable and realistic when it is done. And maybe much cheaper. I always hated the idea of using decoders on anything but locomotives.

[@carllarssen652]

I have a ring end of train device on my flat car will the nce bdt detect it

[@TheDCCGuy]

I’m not sure it all depends on the total resistance across the device. It takes about 10,000 ohms resistance for most detectors to work and if it doesn’t you can always add a resistance wheel set like the one I showed.

[@ronaldrondeau7870]

very interesting

[@jamescraft672]

Did I understand you to say that the gaps in the helix are just on the inside rail?

[@TheDCCGuy]

Yes, only the inside rail is gapped in this case to create 3 detection blocks within the main power block. I did use double gaps at the bottom of the helix as I plan to eventually use the outer rail as a detection block for the signal system. You can do this with these detectors since current does not physically pass through their circuitry.

[@jamescraft672]

@@TheDCCGuy This is in contrast to power blocks, where normally both rails must have gaps. Right?

[@TheDCCGuy]

Yes, detection blocks can be set up within power blocks.

[@jamescraft672]

@@TheDCCGuy My point was that the best way to define power blocks is to create double gaps. (It is possible to use a common-rail approach, for which only a single gap would be required, but that approach has drawbacks, and most people don't use it.) The reason for my comment was that I got a reply from another person suggesting that double gaps are required for detection blocks. As you've explained, that is not necessary. As usual, your video was informative. I appreciate you.

[@pibyte]

20 USD for one block sensor?

[@TheDCCGuy]

It can be an expensive hobby!

[@TOOT222]

Interesting demo, but you can't buy NCE DCC 0205 Block Detectors no one has them.

[@TheDCCGuy]

They can’t get the parts to build them right now. However I did say that the LM-iD detector from DCC Concepts is almost identical and Iron Planet Hobbies has them in stock.