# Block Detection Outdoors



## majral (Jan 13, 2008)

When I originally planned the Jackson County I was thinking of a walk around shortline style of operation with hand thrown switches at towns, 18 months later I am thinking of some form of CTC with remote operation of siding switches, naturally the next thing that crops up is some form of block occupancy detection.

Currently I have converted the staging/storge yard swithces in the garage (Strahan) to remote operation from a panel using JMRI software on my laptop, the next stage is to extend coverage to the junction between the line from the staging and main circuit.

I am reluctant to use traditional Block detection track circuitry, as I want to avoid cutting section gaps, with the problem of maintaining insulated joints and mainly because I am planning to power the switch machines from a separate circuit, allowing remote operation of the switche while the track power is off to allow steam, clockwork and dare I say it battery operation







. 

Have infra-red detection systems been used successfully outdoors or is it a case of designing a G scale axle counter? 

John


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## Greg Elmassian (Jan 3, 2008)

IR is usually problematic due to sunlight and reflections of sunlight. Heat can also be a problem. 

You should hook up with Bob Grosh and brainstorm with him. 

If you haven't read some of his stuff lately, he's doing what you want in terms of functionality, where a box car is spotted on a siding, and the system detects it's presence and commands a sound unit in the box car to make the appropriate sounds. 

I'm sure he will see this post, but he's also on the mls chat most evenings, starts about 7pm pacific coast time. 

Regards, Greg


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## Steeeeve (Sep 10, 2008)

I think bob would tell you that Block Detection is worthless for outside yes because so many things can trigger a false read. Morning dew or even something crossing the two rails could trigger or not trigger a detection and so you end up with a worthless program. Bob prefers transponding with some fancy programming to have a system better than detection.


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## Greg Elmassian (Jan 3, 2008)

Steeve.... Bob uses transponding with block detection... there are blocks so the system knows where the unit is that is transponding. 

and he uses the jmri system.... just as John asked 

So this is why talking to Bob is perfect.... 

Greg


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## toddalin (Jan 4, 2008)

My very simple block occupancy circuit that only costs for the relays, a "wall wart" and track insulators (that you don't want to use). Will work with any engine or railcar with metal wheels.


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## SteveC (Jan 2, 2008)

Posted By Greg Elmassian on 01/25/2009 9:30 AM
Steeve.... Bob uses transponding with block detection... there are blocks so the system knows where the unit is that is transponding. 

and he uses the jmri system.... just as John asked 

So this is why talking to Bob is perfect.... 

Greg 


Greg

I would tend to think that Bob would disagree with your choice of terms using "block detection" as opposed to using "power district detection" with transponding. With the latter no additional wiring is required you use what's already there, and if I remember correctly if using it in a closed loop at minimum three power districts are required, but on a point-to-point that would be two.


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## majral (Jan 13, 2008)

Posted By SteveC on 01/25/2009 5:20 PM
Posted By Greg Elmassian on 01/25/2009 9:30 AM
Steeve.... Bob uses transponding with block detection... there are blocks so the system knows where the unit is that is transponding. 

and he uses the jmri system.... just as John asked 

So this is why talking to Bob is perfect.... 

Greg 


Greg


I would tend to think that Bob would disagree with your choice of terms using "block detection" as opposed to using "power district detection" with transponding. With the latter no additional wiring is required you use what's already there, and if I remember correctly if using it in a closed loop at minimum three power districts are required, but on a point-to-point that would be two.











Thats intresting I was sceptical about the relaibility of DCC block detection cicuitry outdoors, though it might be worth giving transponding a go.

Currently I operate a single power district, but have set up a separate power bus from the garage to the main line if I need to add an additional booster or power disrict.

I already have most of the hardware with transponding detectors and circuit breakers in stock, just need to read up on transponding detectors. 

Sounds like the subject of a pilot study for the staging yard and the section to the junction with the main line circuit.


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## SteveC (Jan 2, 2008)

Posted By majral on 01/25/2009 7:06 PM
{snip...}[/i] Currently I operate a single power district, but have set up a separate power bus from the garage to the main line if I need to add an additional booster or power disrict.

I already have most of the hardware with transponding detectors and circuit breakers in stock, just need to read up on transponding detectors. 

Sounds like the subject of a pilot study for the staging yard and the section to the junction with the main line circuit. 

John

Maybe the following links may help a bit, they are to topics in the MLS Archived Topics in the old forum software.

Detect Derailments - Is there a way with DCC?[/b]

Block Detection Outdoors[/b]

Garden Railways DCC article[/b] 
Using transponding to reduce the amount of wiring[/b]


How to get feedback from a turnout[/b] 
Here's one from the new forum software.

Transponding and Detection zones[/b]


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## Greg Elmassian (Jan 3, 2008)

Neither of you guys apparently have read Bob's posts. He is locating cars very precisely, and he unfortunately had to have more "power districts" to do this, although he is doing some tricky stuff with "time since leaving district a into district b"... 

Also, while you are right on the minimum number of blocks you could use theoretically, the original poster wanted something more sophisticated the absolute minimum to qualify as block detection. 

Anyway, I made a helpful suggestion and I'm getting minutia and terminology lessons instead of trying to address the general question. My best advice is already delivered. 

Greg


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## SteveC (Jan 2, 2008)

Greg

That sir is a mite harsh I think, additionally, I would tend to bet that I've taken the time to read through all of Bob's postings on DCC since he first posted here on MLS.

If you take the time and read through the topics that I've listed above, I believe that you'll find that more than once Bob has stated that Transponding and Block control in DCC are two distinctly different things.


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## Greg Elmassian (Jan 3, 2008)

Yes, you are correct, they are definitely different things. 

Greg


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## High Ball John (Jan 26, 2009)

Hello.

I'm often lurking here but never posted before.

I'm one of those from over the pond, so be gentle please.

My railway can run under automatic control and it uses bock detection.

I found that using the TRACK-DT from Dallee Electronics with a 100ohm resistor soldered across the sensing coil provides reliable outdoor block detection, whatever the weather.

Hope this is of some use.


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## Steeeeve (Sep 10, 2008)

Posted By Greg Elmassian on 01/25/2009 9:30 AM
Steeve.... Bob uses transponding with block detection... there are blocks so the system knows where the unit is that is transponding. 

and he uses the jmri system.... just as John asked 

So this is why talking to Bob is perfect.... 

Greg 



From my discussions with him, he seems to not like the term "blocks" since it isn't like block detection like others use it. He does virtual blocks via transponding. I also think he got away from JMRI and created his own program using the same programming language and some of the same code.

I could be wrong though  Only Bob knows!


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## bdp3wsy (Mar 14, 2008)

If you go to this site: http://www.largescaleonline.com/members/emag/Lights_LED_41/Simple_Trackside_Signals_158_printer.html They have the best signals for outdoor use. I have 12 on the outside layout and leave them out all year even under snow. They cost about 5 bucks and take about 45 min. to construct. I havent had one fail yet. Jack


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## terry_n_85318 (Jan 3, 2008)

No access to web site.


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## bobgrosh (Jan 2, 2008)

Ok, I spent four hours responding to this topic, and then it lost the post....

Thats the third long post in a row that I've lost.

Screw it.

Follow the-ALLY.blogspot.com , I'll repost the reply there in a few days.


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## aceinspp (Jan 2, 2008)

To bad AC did not bring out their system as it looked like the deal. I think it was patterned after Atlas O scale system. Later RJD


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## toddalin (Jan 4, 2008)

Posted By aceinspp on 02/05/2009 12:38 PM
To bad AC did not bring out their system as it looked like the deal. I think it was patterned after Atlas O scale system. Later RJD




The AC system was to be operated on essentually the same principal as the Tortoise Bump Accident Sentinental System (Bump A.S.S.) documented several times in the past on this site. You should be able to do a search and find it here.

I had submitted a prototype to Lewis and their engineers evaluated it and determined that is was very similar to the Atlas system that they had already devoted so much effort into. I came up with and built my prototype in a day.

Best I can tell from what I saw from Lewis, like my systems, including that shown above, their system would also have been triggerd by the wheel bridging the gap and sending a pulse latching a relay (with a timer chip) and required the rail insulators. They would just have included them in a section of track like the rerailer and in fact my idea was to build it right into the rerailer track.


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## bobgrosh (Jan 2, 2008)

OK, I edited this using Google docs and pasted it here.
Finally, I found a way around the crashes in this forum editing code.
Will block detection work outdoors? Well, sort of.
I am a little weird. My definition of WORKING is that it works 100% of the time, no matter what!
I spent six months trying to get block detection *WORKING *outdoors. I learned a lot. I got it to work 99% of the time, ON MOST DAYS! No matter what I did, there were days when it just won't work at all.
Then I removed block detection and went to Transponding.
Here is a picture taken with my cell phone, after Transponding was *WORKING*. It was taken during the height of tropical storm Fay, here in Florida.

I warned you, I'm a little crazy!

YES! the trains were running under control of some JMRI automation scripts. But then we don't get snow down here, so I find it fun to run trains in the rain.
There was 4 to 6 inches of water covering most of the yard. At places, the water was half way up the web of the rail. 

*Trains were leaving wakes in some places.*

The four 8-amp Digitrax boosters were drawing a combined six amps of power above the normal current for lights and accessories from the DC supply, even with all the trains stopped.

Despite Tropical storm Fay, Transponding was *WORKING*. The JMRI scripts performed flawlessly. 

I should warn the reader, all my decoders are inside rubber bags used by the RC boat guys for their servos and radios. Don't try this with just any old DCC equip ed loco. 

OK, so you want to use block detection outdoors. 
Follow all these suggestions and they will help you get the railroad to "sort of work".



These help prevent false occupancy. The test is that the occupied light goes off instantly when a resistor equip ed axle is lifted from the track.


 Make sure that every feeder to rail attachment is AT LEAST TWO FEET from any other feeder attachment. ( Don't attach two feeders to either side on an insulated joiner, or a block and common feeder to opposite sides on a track.)
 Use Split jaw, or Hillman clamps. Turn them all bottom up and spray paint a couple heavy coats of "PlasitKote" or lacquer.
 Use Split-Jaw rail insulated joiners for all gaps. In addition, insert a 1/8" thick plastic shim between the ends of the rails, over tighten the screws and apply cryloacric glue to the joint to seal out moisture.
 To attach a feeder, use Split-Jaw feeders. Attach the wire to the copper lug, over tighten the screws, then dip it in "Liquid electricians tape" (available at Lows or Home Depot). Cover the first three inches of the wire, leaving only the end of the copper part exposed where it attached to the joiner.
 Follow the instruction on the Digitrax site to add the heat sinks to the BDL168 card.
 Follow the instruction on the Digitrax site to add resistors to the BDL168 to DECREASE the sensitivity of the DBL168 card. You want to reduce the sensitivity until a single wheel set with the recommended resistor NO LONGER causes the block to show occupied. Make sure you have the booster set to the O/G setting when you do this.
 Use a resistor on your wheel sets that is about half the recommended resistance. This will then reliably make the block show occupied but ignore any current being drawn by whet leaves or moist roadbed.
 TEST YOUR BALLAST! Assemble 20 feet of track. Wire it to a detector. Place the track on a porous plastic weed stop so it will drain through the sheet. Fill a five gallon bucket half full with ballast. Fill with water and 1/4 cup of vinegar. Let it set for an hour. Pour the wet ballast on top of the track and broom the ballast from between the rails. If you are lucky, block detection should work immediately. As soon as the ballast drys, it should definitely work. If NOT, look for another source of ballast. Wait a day, wet the track with a garden hose and repeat the test. As a final test, sprinkle a hand full of your favorite fertilizer over the ballast, and give it a LIGHT spray of any other bug poisons or lawn chemicals you use (including a teaspoon of Miracle Grow if you use it on your railroad). Water it in and test again.
 Limit the length of a detection block to about 20 feet. If a block needs to be longer, install an insulated joiner ten feet from each end. Install a "Y" in the feeder and connect the two ten foot sections to the block detector. Leave the middle of the block undetected (wired direct to the booster.) Most software will accept this as one detection block. For single ended sidings, just wire the first 10 feet after the turnout to the detector.
 These help insure detection. The test is that the occupied LED turns on instantly when ONE resistor equipped axle is placed on the track. 


 Do not expect a caboose or car with an LED to draw enough current to show occupied. Add the resistor you use on the wheels.
 Make sure the feeders are of a heavy gage wire, the longer the run the heavier the wire will need to be.
 All rail joiners MUST be tight, Use Hillman or split Jaw. For Hillman, use LGB track paste, For Split Jaw it is not required.
 Wheels and track need to be clean and dry.
 
Now let's clear up some confusion in the posts to this topic.
The number of boosters (or power districts) has nothing at all to do with the number of Transponding zones. You can have 32 Zones on one booster, or have four zones on 6 boosters.

Zones (Transponding) and Blocks (Detection) have nothing in common. You can have one Zone that is divided up into 10 blocks. - OR - You can have one block divided up into three zones.

Part of the confusion comes from a statement I made:

"I have four boosters. So, I have five feeders going to the track, One per booster plus a common.
When I hooked up four Transponding receivers I just ran each of the four booster feeders through four Transponder receivers."

The point was, if you have four power districts and only need to hook up four Transponding zones, then you may not need any additional wires going to the railroad.

It just worked out that I had wired the ALLY so that there were three boosters on the mainline, and one that fed all the sidings. That was the optimal use for the power management.

Without adding a single wire, I also had four Transponding zones. Three on the mainline and one on all the sidings. Not a bad arraignment for automating the railroad.


On the ALLY, I have four boosters: 
The booster outputs go to terminal strip "A". 
Terminal strip "B" has wires going through the RX4 Transponding receivers to terminal strip "C".
Terminal strip "C" has wires going to the tracks.












On the ALLY, it looks like this:










Most of the year, one booster output on terminal A is wired to all the screws on terminal B. The other three boosters are disconnected so that a lightning strike can't get to them. Once or twice a year, I need to run 8 or more trains at once, so I need more current, or I want to mix DCC and host a live steamer, so I need separate power districts. To do that, all I need to do is move three jumpers between terminal strip "A" and "B" and power up the three additional boosters.


Note that the picture shows 12 zones. The four zone receivers between B2 and C2 were added while experimenting with JMRI and are slated to be removed. You can also see that the blue edge connectors have only a couple power connections. No detection blocks are connected in this picture.

*Advantages of Transponding *
Compared to block detection, Transponding has several advantages.


 Things that draw current from the rail do not generally cause problems for Transponding, wet track, stationary decoders, Signal lights, building lights etc, can be wired to the rails. 
 Far fewer insulated joiners need to be installed. While you will need more detection blocks than trains for occupancy detection, you will be able to track multiple trains, and even individual cars in a single Transponding Zone.
 There is far less wiring. This is a real advantage for garden railroaders. I've found it takes 5 to 7 times as many feeders to do block detection and accomplish the same thing.
 Dirty wheels and track can cause cars to not make a block indicate occupied. Transponding only needs to get one ping back to the system to tell the software that it has entered a Zone. Transponders send hundreds of pings per second. Transponding works better on dirty track than block detection. I've even noticed that Transponding packet reception IMPROVES when the track gets wet.
 Transponding tells you exactly WHICH DCC address entered a zone, not just that SOMETHING entered a block. This make tracking a car or loco simple when writing program code. 
 When you add Transponding to a Digitrax Chief system, you also gain the ability to read back CV's on the main while trains are running. A big advantage when you want an automation system to read things like the speed table. It's even possible to read back a count of the number of wheel rotations for exact positioning or calculating accurate speeds. (Requires an SFX sound decoder with custom programming in the decoder.)
 
I don't want to give the impression that setting up Transponding is far simpler than block detection. I had to spend two weeks trying to get it to WORK to my standards. There is a lot of misinformation on the Web about Transponding and how to wire it up. I will be publishing a guide like the one above for block detection that will help those wanting to install Transponding. However, that will be a whole new topic.


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## jbooker (Jan 15, 2008)

Hi Bob,

Thanks for thhe post and picture of your setup. Can I ask what gauge wire you use through the RX1? It looks very small. Does that reduce the power or distance you can go from terminal c to the track?

Thanks,
Josh


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## bobgrosh (Jan 2, 2008)

Yes, It looks small, perhaps because the insulation is thin, while the surrounding jumpers have a very thick insulation.

Aside from that, they are a little smaller, they are 14 ga, the jumpers on the rack are 12 ga, the actual feeders to the rails are 10 ga. On one long run, I doubled up on the 10 ga feeders.

To keep voltage drop to a minimum the longest lines, going from the rack to the tracks have the largest wires. The wires going through the RX4's are only 12 inches. Because they are so short. there is less voltage drop across them than there is on the much larger wires leading from the rack to the track. In fact, I wasn't even able to measure any loss from B to C at 6 amps. I do get close to a 0.4 volt drop on the lines going to the track at 6 amps. Not enough to worry about.

B0B


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## High Ball John (Jan 26, 2009)

Hi Bob and all,

I thought some of my experiences with block detection would be interesting for you.

I'm glad Transponding works for you Bob, there are some guys over on the RR&Co forum who could probably do with some of your advice.

Firstly I know little, if not less that little, about anything Digitrax.

Can't say I've ever had a problem with block detection, although I know people who have. Seems to work 100% for me, although I've never run in the rain. I don't get false detection even when the ground is wet.

I use the Track-DT from Dallee to do my block detection, for outdoor use, and as recommended by Dallee, the sensor needs to be desensitised to with a 100ohm resistor across the sensing coil.

Some of the rules stated by Bob I follow, some I don't.

1) I do use rail clamps at all track joints, insulated or not, and also for all power connections, but I don't do anything special to them, except tighten them.
2) Heavy gauge wire is used (it's called 6mm wire here, don't know what the equivalent American wire gauge number is).
3) I always wire both rails in each detection section, even though only one is strictly necessary. Both wires are twisted together to eliminate inductance problems. In most cases there is only one feeder pair to each block.

My blocks do go on instantly current is drawn in the block, but they don't turn off as soon there is no train in a block, its not necessary. There is about a half second lag, to account for temporary loss of current draw due to dirty tracks, traversing points etc.

On these points I break Bobs rules:

1) Some feeders are as close as 20cms from others.
2) My longest block is about 20 meters, and several are longer than the minimum stated by Bob.
3) Ballast is used, but nothing special is done to it.

When block detection is used there is a lot of wiring to do.

Love your web site, Bob. Some great ideas on there.

I hope this is useful to someone.

Regards
Cliff

Sorry don't know how to embed pictures or video here. Look up ytgeorgc on youtube if interested.


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## SteveC (Jan 2, 2008)

Here ya' go Cliff, to embed the video using the "Quick Reply" editor at the bottom of each topic page just copy and paste the embed code from the YouTube just to the right of the current video being played.


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## aceinspp (Jan 2, 2008)

Keep it simple you guys getting to high teck. Later RJD


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## bobgrosh (Jan 2, 2008)

Posted By aceinspp on 02/08/2009 7:12 PM
Keep it simple you guys getting to high teck. Later RJD


Yea RIGHT!

And. I'll take a refresher on Morris code, renew may Ham license and give up my cell phone.

Or, maybe, Go back to three rail AC and install mechanical reversers in my Loco.

Or learn to saddle a horse.

Or take movies of the kids with 8 mm FILM so I can splice together pieces with acetone.!

Or run fifty feeder wires for block control.


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## Greg Elmassian (Jan 3, 2008)

If you want more features, you have to have some increase in complexity. I must make that statement 10's of times each week, especially to people about their personal computers. 

The stuff Bob is doing is pretty much cutting edge, in terms of how he has gotten it to work, and what it can do. I think that a certain contingent of the hobby, especially new people, will be looking to do more, and I notice the younger generation loves the "bells and whistles". 

So, to each his own. 

Regards, Greg


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## GG (Jan 1, 2009)

Steve, your video's are pure class. 

The ultimate of the hobby. This is to aspire to. 

I have a long way to go here. 


gg


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## SteveC (Jan 2, 2008)

Posted By GG on 02/08/2009 9:21 PM
Steve, your video's are pure class. 

The ultimate of the hobby. This is to aspire to. 

I have a long way to go here. 


gg 


GG

While I would like nothing better than to say "thank you", however, I must point out that all I did was explain to Cliff how he could go about embedding his YouTube videos within his replies, and then included two of Cliff's videos in the reply. He does have a very beautiful layout doesn't he.


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## GG (Jan 1, 2009)

Posted By SteveC on 02/09/2009 6:59 AM
Posted By GG on 02/08/2009 9:21 PM
Steve, your video's are pure class. 

The ultimate of the hobby. This is to aspire to. 

I have a long way to go here. 


gg 


GG

While I would like nothing better than to say "thank you", however, I must point out that all I did was explain to Cliff how he could go about embedding his YouTube videos within his replies, and then included two of Cliff's videos in the reply. He does have a very beautiful layout doesn't he. 






oops.... sorry and my comments redirected to Cliff..... 

 Very nice layout. 


gg


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