a new way to do train detection

Model Railroader Electronics and DCC
1

I’ve designed and put into the public domain, a complete detection system that does NOT require any modification to any rolling stock or locomotives, and is independent of track power.

As such, it will work on DC or DCC or for that matter ANY form of power used for a model train. It’s designed to be cheap and simple, yet reliable.

The system is Arduino based, and includes basic, simple signaling as part of detection, but if that’s used is up to you. It supplies a simple logic level signal to indicate that a block is occupied.

The design was initially introduced on the TrainBoard forum, and I’m trying to get more exposure so more people will try it. There are videos and complete documentation that includes the code for the Arduino, schematics and single-sided PCB layouts so you can make the boards at home. There is also some technical details of how it works.

The estimated costs per block is between $9 and $16 depending on how fancy you get in the build process. The outputs are on 0.100 centers, so many types of connectors can be used, from simply soldering wires to the pads (not recommended) to simple pin headers, to screw terminals. The wiring to external devices is whatever you have around, and I use the wire from CAT5 computer cables.

Besides the Arduino modules, the only external components are resistors for the indicator LEDs, the IR sensor modules and the IR source LED and its current limiting resistor. Simplicity by design!

http://www.trainboard.com/highball/index.php?threads/different-way-to-do-detection.91951/

The video production isn’t very good, and if you watch all 10, the final system implementation is worth it. Again, all the code and schematics and board layout is done, and the discussion should help you understrand

2

Local enters the block with and engine, 10 cars and a caboose, 48 axles. Stops mid block and sets out 1 car at an industry. Departs block with an engine, 9 cars and a caboose, 44 axles.

Is the block occupied or unoccupied?

3

Sounds like we are being given a sales pitch. Isn’t that against the Forum rules?

4

What part of public domain don’t you understand?

5

I understand it perfectly… I also have been around the block a whole lot of times.

6

Occupied, obviously…once the train clears the block, just touch the block reset, and all is OK.

Conversely, the same environment, but an 0-5-0 operation ADDS a car with 4 axles…when the train leaves the block, is it occupied or unoccupied???

The answer is unoccupied, because the logic prevents the count going below 0.

Look at the videos and read the docs on TrainBoard…actually, I count anything larger than a minimum size, which is about 1/4 inch. The system actually ends up counting trucks because they only cause 1 transition through the sensors, but I just count any appropriate transitions, defined by the state machine logic.

7

I don’t have anything to sell other than the idea, and that’s free!

8

Another interesting Arduino application.

Thanks crusader27529

Dave

P.S. I like the price for the plans. You can sell me as much of that as you want to![swg]

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Please let me know what you think of the system, and ask any questions that you have…

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Looks interesting. I will take a look. I generally prefer current sense systems that aren’t point based, so you can exclude sidings, and adding cars in the middle will definitely be detected. There are definitely use cases where a point detection system is more usable, and perhaps a combination of systems will get the best fo both worlds - easy to tell direction of travel while no issues with things like setouts. A current sense system can do direction, but to do so it must track the status of each block, and also know the railroad, so that if it sees block 5 active and the next one active is block 6, and it knows block 5 connects to block 6, then something just moved from 5 to 6. Not as easy as just seeing which sensor was tripped, east end or west end.

–Randy

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I gave it a read, interesting enough approach.

But for me current detection works just fine.

Signaling and detection are generally about mainline operation. I model an era when mainline trains had cabooses. Light the caboose, and the whole train is detected. Size blocks properly, and use overlapping sub blocks for interlockings. Light most passenger cars, especially tail end cars. No worries, current detection works fine.

I run my trains with DC, so it is also easy for me to monitor direction.

And my interlocking sub blocks also lock out turnouts so they cannot be thrown under a train - just like a real life interlocking plant.

All done with $3 relays rather than computers or processors.

I use Dallee inductive detectors, pricey but rock solid reliable.

And the Dallee detectors have dry contact relays on board as the heart of my signal system - that combined with spare contacts on relays used to operate turnouts, is a complete signal system - with no processors.

All with wireless radio throttles…don’t need no processors here…

Sheldon

12

if you have a larger layout where a number of occupancy detectors are required, your looking for something that is reliable, inexpensive and worry and maintenance free, buried under the layout.

I’m sure that the Arduino board could be replaced by an 8-pin Pic processor, but even such an implementation would be more complicated than a simple diode drop detector. Of course, such detectors aren’t intended for DC.

but modelers interests also justify approaches …

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What are all you current sensing guys going to do when battery powered, Bluetooth controlled trains are running on dead rails? [:D]

BTW, I’m going with current detection as well, but I’ve only gotten as far as putting the coils on my feeders. I guess I need to hurry up before there’s no current to detect.

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rrinker wrote the following post 5 hours ago:

Looks interesting. I will take a look. I generally prefer current sense systems that aren’t point based, so you can exclude sidings, and adding cars in the middle will definitely be detected. There are definitely use cases where a point detection system is more usable, and perhaps a combination of systems will get the best fo both worlds - easy to tell direction of travel while no issues with things like setouts. A current sense system can do direction, but to do so it must track the status of each block, and also know the railroad, so that if it sees block 5 active and the next one active is block 6, and it knows block 5 connects to block 6, then something just moved from 5 to 6. Not as easy as just seeing which sensor was tripped, east end or west end.

–Randy

This setup will also detect extra cars added to a train automatically.

As far as direction detection, the ONLY reason I care about direction is at a block boundary, so I can signal the block that the car/train came from that a car has left…same thing for the block that the car in entering. That signal counts up a count for the block where the car is entering, and counts down for the block that the car is exiting from.

If the count is zero, unoccupied, otherwise occupied…

The system works with ANY type of power, even battery, and detects ALL cars without modifying the rolling stock. The way it operates is completely different from the previous techniques used. It’s very reliable and easy to setup.

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if you have a larger layout where a number of occupancy detectors are required, your looking for something that is reliable, inexpensive and worry and maintenance free, buried under the layout.

I’m sure that the Arduino board could be replaced by an 8-pin Pic processor, but even such an implementation would be more complicated than a simple diode drop detector. Of course, such detectors aren’t intended for DC.

but modelers interests also justify approaches …

greg - Philadelphia & Reading / Reading

The technique used is quadrature detection, and as such the detector requires 2 inputs, plus the guaranteed communications links to the blocks connected to each boundary requires 3 lines each, so an 8-pin PIC would never work.

You really ought to look closer at the implementation of my system before you try to come up with alternatives…the system is engineered as well as any commercial system. I’ve been designing microprocess or based HW devices since 1976.

The design goals were based on performance with cost a close secondary control in the design. At about $10 per block with excellent reliability, I feel that the goals were reached. Add in that the HW is simple enough to build at home just makes it a candidate for both individual layouts and club implementations.

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I gave it a read, interesting enough approach.

But for me current detection works just fine.

I run my trains with DC, so it is also easy for me to monitor direction.

Sheldon

First, running DC and using current detection doesn’t make alot of sense to me, since the detection won’t work when a block is unpowered.

Second, the only reason for direction detection is to determine which block to signal to count the number of cars in that block up or down, depending if the cars are going into the block or out of the block. You don’t understand the detection logic…

The state machine determines a valid transition at a block boundary and the direction of the transition, and signals the adjacent blocks (yes 2 blocks) to count up or down depending on the direction of the transition. When a count for a block is NOT zero, the block is occupied, and if it’s zero, it’s empty and unoccupied.

LOOK AT THE POSTED VIDEOS…it explains how the system works.

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crusader27529:

Seems like you are being given a hard time. Please hang in there! (I’m sure you will).

It’s kind of like arguing that the world is round 600 years ago.[(-D][(-D][(-D]

Dave

18

Obviously you are not familiar with the Dallee detectors or their system.

Respectfully, maybe you are the one who needs learn a little more about older systems what work just fine before you start telling people what they don’t understand.

They do work when the train is stopped, because there is an accessory device that puts a high frequency bias current on the track. It has no effect on the loco or the lighted cars, but the inductive dectectors detect the presence of the parked loco or car.

And that’s not the only way to do it. Maybe you should go into the MR archive and look up “twin T”.

I detect direction because I can, polarity determines east and west, the dispatcher sitting at his CTC panel kn

19

Do exactly what the prototype does, you add a track circuit for detection to the track. Since its for detection it doesn’t need any sophisticated controls and doesn’t have to be routed through switches.

20

Not quite. There are some hurdles with the proposal. Like the first one I brought up. If you make a set out between detectors the system will have to be manually reset.

That’s not an automatic system. That means somebody has to manually rest the signal system everytime the car count goes down on a train. Is there a detector to detect when the proposed detector didn’t detect a set out?

How does the system detect a track occupancy after a pick up (I pick up 5 cars but leave the caboose on the main)?

What happens if somebody moves their hand (or a Bright Boy) over the track? Will it trigger an occupancy?

How do you hide the detectors so they aren’t visible on multiple main track or controlled sidings (since they measure horizontally instead of verticaly like most optical detectors)?

Maybe all these things can be accomodated, but they are legitimate concerns.

I wouldn’t want to use this type of thing to drive a signal system (and I model a dark railroad), but it might have a use as an automated OS bell. I wouldn’t care about car count. Mount one in front of the depot and it would ping an OS based on direction. The hard part would be limiting it to one ping per “train” and handling trains working at the station.