Detection Systems ????

[streetspook]

Hi All and thank you ahead of time for any and all responses. I have a pretty good size mountain with a double track going through it and it is curved so that you can not see through it. My plan is to have some kind of detection/occupancy system (not completely sure of the terminology) so that I can pull a train inside and park (hide) it for awhile and allow another train to go through the same mountain. I may even want to be able to uncouple the loco from the cars and use it elsewhere on the layout so the system will have to let me know when I have the train in the right position to do that.

Now at least a year or so ago, I went to a train show in Monroe WA and saw a guy that had made some kind of detection system that worked in light or dark and appeared to be real simple. I don't remember if it was just an infra red system or something else entirely. Don't ya just love getting old? WHAT??  Oh, it's time for my pill

[gregc]

sounds like you'll want several infra-red led/transistor type detectors to indicate presence at multiple locations within the mountain.  Once you've figured out one detector, it should be easier to add more.

a combination of the circuits below could be your answer.  Since things will be hidden, the led and photo-detector can be mounted above truck level on opposite sides of the track at a slight angle to avoid the gap between cars.

while the first circuit shows how multiple LEDs could be driven thru a single resistor, it shows an output, P1, that provides a high output signal when the presence of a car blocks the light path shutting off the photo-transistor.

the circuit below shows how an LED on a panel can be driven by a transistor when the input to the transistor is high.  The path between the 2.2k resistor to Vcc that can be connected to the output, P1, in the above circuit instead of Vcc.

[RR_Mel]

I have what sounds like the very same thing on my layout.  I went with standard optical detectors, they aren’t visible outside the mountain.  I have two detectors to spot my passenger cars one on the end to tell me when the observation car is clear of the turnout the other to spot the locomotive.  I have a third detector to spot the coupler couplers over the Kadee 309 electronic uncoupler.

I operate dual mode (DCC & DC) so optical detection isn’t a problem.  I can drop and pickup my passenger cars using either a DC or DCC locomotive.

I use Rob Paisley circuits for my dectors:

http://home.cogeco.ca/~rpaisley4/PhotoDetectors.html

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

My Model Railroad   

http://melvineperry.blogspot.com/

Bakersfield, California

I'm beginning to realize that aging is not for wimps.

 

 

[streetspook]

Thank you Greg. Your suggestion may be a bit outside my abilities and I don't live where there are multitudes of modelers or hobby shops.

[streetspook]

Thank you Mel. I didn't even think about the need for the third detector. However, i think this suggestion like Greg's may be beyond my abilities. We shall see. Bill

[RR_Mel]

streetspook

Thank you Mel. I didn't even think about the need for the third detector. However, i think this suggestion like Greg's may be beyond my abilities. We shall see. Bill

 

It might not be a big deal.  Check with Rob, he has circuit boards available for a lot of his circuits.  His optical detectors are a rather simple circuit to build.  There is a good circuit in the November Model Railroader for a driver circuit for the Kadee electronic uncoupler.

I can try to help you through e-mail if you get in trouble, the circuits I’m using are simple to build and even simpler to install.

Good luck.

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

My Model Railroad   

http://melvineperry.blogspot.com/

Bakersfield, California

I'm beginning to realize that aging is not for wimps.

[hon30critter]

Hi Bill:

I agree. The electronic circuit diagrams can be a little daunting.

If you want ready-made then here is one supplier who offers a variety of sensors. I have never used their products so I can't speak to ease of installation etc., but I have made my own detectors and installation was easy.

https://www.azatrax.com/ir-model-train-detector.html

I would suggest considering the MRD6T. It will give you six sensors which could be useful if you want to monitor both tracks.

I recognize that they are not cheap, however the completeness of the circuit (i.e. you don't have to provide a bunch of other components to finish the job) actually makes the price fairly reasonable IMHO. You can build your own IR detectors for very little money but adding in things like the variable delay can get complex as I'm sure you are aware.

Good luck with your project. If you want a diagram for a very basic IR detector I can provide one but you still have to build it yourself. Let me know.

Dave

 

[mlehman]

If you want to detect the position of several trains in different places, the costs of using IR detectors starts to add up. You may find the most cost effective thing to use is closed-circuit TV. Harbor Freight offers a 2-camera system, full color/low light LCD flat panel display for around $75. Sometimes a picture is worth a 1,000 words.

[RR_Mel]

I agree with Dave on buying the MRD6T detector, 6x2ft for $53.50.  I had not seen their site before but from what I see I’d go for it.  Much easier than building it up from scratch, nice looking package too.  The 6 detector module would give you occupancy on both tracks, very nice to have.

You didn’t say whether you are running DC or DCC, DCC would be a piece of cake to uncouple or park your locomotives in the mountain.  If your running straight DC use a block switch to park.

I built my layout with sidings inside my mountain specifically so that a freight can inter the tunnel, be parked on a siding and a passenger can follow but be first out of the mountain or vice versa.

Heads up on using IR detection: Make sure the IR emitters are not pointed to little eyes, always aim the IR emitters away from kid eye level.  IRs can be problematic to properly align because you can’t see the beam with your eyes, use a camera with an electronic viewfinder to see the IR beam.

I use long and short range IR diction all over my layout and it really works great if properly aligned, even slightly out of alignment they can make you use profanity.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[7j43k]

If the OP is intending to uncouple a locomotive from a train in a hidden siding, I'd recommend television.  So he can see what he's doing.  Might be able to skip the detectors, too.

 

 

Ed

[BroadwayLion]

LION goes for the simple brute force methond. Him install a reed switch between the gauge, and magnets under the locomotives.

ROAR

[rrinker]

 Him also uses helper paws when soldering wires, it appears.

                 --Randy

 

[RR_Mel]

For what it’s worth,

 

I used magnets and reed switches on my G gauge and they worked very good but I’ve never had much luck with them in my HO stuff.  With my conversion to dual mode DC/DCC I’ve also tried several types of current detection over the last 10 years but found out that they can be very problematic too.

 

Properly installed and aligned optical detection whether viewable or IR has worked flawlessly on my layout since 2008.  There is a learning curve to perfect long range beams for block detection but done right no problems.

 

I use across the track and vertical alignment where I can and where it can’t be hidden easily reflective IR through the ties does well too.

 

I have hidden LEDs everywhere, in rocks, buildings, bushes, tree trunks and telephone/power poles.

 

The best thing about using optical is any and all of your rolling stock triggers the detectors without any type of modifications, power on or power off.

 

I tried a video camera in my mountain originally but gave up on it for fine spotting.  A light beam across the track either vertical or horizontal between the cars or lead on a locomotive is far more accurate than a camera or a reed switch, ¼” optical stopping is easy using DC mode with a relay to automatically drop power.  Visual spotting using LEDs on the control panel works good for DCC mode.

 

I also use optical detection to operate my signals, I originally used Rob Paisley circuit detectors but current detection in DCC mode is too touchy.  The old Twin-T circuit in DC mode was fool proof but that won’t work in DCC mode.

 

By buying parts in bulk I’ve got the cost down to less than $4 per detector.  I use a $20 switching power supply that provides 5 volts at 15 amps that powers all of my detectors, signals, logic circuits as well as LED lighting with plenty of reserve power for future expansion.

 

For this old SP guy optical detection has worked out very good and is more reliable than any other type I’ve tried in my 60 plus years of model railroading.  No Tweaking required once it’s installed correctly.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[streetspook]

Thank you Dave, I will check out the site.

[streetspook]

Thank you Mike, I am looking at that kind of system as well. Thank goodness that market has expanded and there's lot's of inexpensive product.

[streetspook]

Thanks Ed, that does seem to be the front runner.

[streetspook]

Darn it Mel, now you've given me pause to rethink using cameras but most of your descriptions on what and how to use the sensors leaves me with a headache. So back to thinking about it. I may just have to try one and see how it works out.

[streetspook]

Thanks Lion, always good to hear your roar!

[mlehman]

I think both sensors and CCTV have their place. For instance, having a simple signal light tell you things are right is less distracting than a TV screen.

But the weakness of sensors if that don't tell you much when things go wrong. A car can be derailed or uncoupled and the sensor would just tell you "OK" so lang as it's sitting over the sensor. Or the sensor indicates no occupancy, yet you could see on TV it's sitting right next to the sensor, but not in the field of sensitivity.

The fact that you want to use whatever you decide in order couple, etc is to me an argument for TV. Mel may have everything 100% reliable on his RR, but I can't make that claim (nor could the prototype for that matter. On the prototype, they did rely on signals, but the presence of Mark I eyeballs was also important. CCTV gives you a way to put your eyes where they need to be, esepcially on occassions where there is some doubt about the signal indication.

[RR_Mel]

Mike I wasn’t knocking CCTV, I just didn’t need it and optical detectors filled the bill for operating my layout.  I guess because the Op titled the thread Detection Systems I kinda got carried away and took it for granted he was looking for detection, not for just uncoupling.

 

Positioning a camera to stop and uncouple would work very good.  I needed detection for operating my signal system and to automate my layout.  I’m not really into train operations so I have to automate stuff to keep everything working, my field of vision is very narrow and I forget to set turnouts and throw switches so detection and automation is critical to me.

 

I use detection to operate my 32 target signals, keep my locomotives from hitting open turnouts, keep the track polarity correct and operate crossings as well as stop my trains on my sidings.  There is no way I can keep all that stuff working correctly in my head with my narrow brain width.

 

Optical detection works great even in DCC mode with the exception of stopping a locomotive, dropping power is not good in DCC mode and I’m not one for running my layout with a computer.

 

The main reason I went into so much detail about optical detection in my earlier post is because of the problems I ran into using current detection.  Current detection is almost foolproof on a DC layout but can be a nightmare using DCC.

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[JDberlin]

I have used this very device and one need not be an engineer to install

all six pairs of optical detectors and you can add additional LEDs for each detector--I added two additional for each detector-one flashing and one straight-screws to do this are on the board- plus the board has six LED lights built-in as well.  Mine are buried inside a train station.

[rrinker]

 Funny you had problems with current detection with DCC. It's infinitely easier, because there is always power to the rails, so no need for a bia power supply to keep a trickle fo current flowing to detect stopped trains, plus you only have to detect one direction of current flow. Diode detectors (not good in DC or DCC, they cause a voltage drop) only need a single diode for DCC vs teh back to back pair needed for DC. DCC allows a simple current transformer detector (no voltage drop), if you build them yourself they can be like $5 per block, you can buy commercial ones at about $10 per block or less.

 Current detection is better for block occupancy, much simplere than the extra circuitry needed to trigger optical detectors and reset them only when the block is clear - you could need up to 3 sets of sensors per block and still have a short power move. 'disappear' from detection.

 Optical detection is better for spot detection - grade crossings, hidden staging to make sure the train is clear of the fouling point, etc. Those things are more difficult and complicated to do with current detectors.

 Our club layout uses current transformer detectors and considering the layout is a sectional and is taken down and rebuilt multiple times in multiple venues, and travels in some enclosed utility trailers, the system is quite robust - rearely if ever requires any adjustments, just plug all the wires together between sections to get power, accessory power, cab bus, and detection system all linked up (an Anderson PowerPole connector plus a pair of phone cords) and it's ready to go.

                    --Randy

[streetspook]

Very good points Mike. Thank you. Bill

[streetspook]

Mel, I'm modeling DCC HO and am not an "OPS GUY" either. I want to be able to detect as well as see to couple/uncouple. The convo's on here have convinced me that really both may be the best way to go. Thanks again for your detail and I hope to find a off the shelf system that is easy to install and it looks like there is at least one outfit out there that does just that.