Reflective detectors : Axle accuracy?

Dear Terry,

In your experience, can reflective detectors be made/adjusted/aimed to detect HO axles rather than the underside of the car floor?

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Caption error, Figure 6

On page 6, the figure 6 caption is incorrect - the figure illustrates the “DC 5V Relay Control Panel Controller Module with Optical Isolator”, not the sensor.

Second paragraph, page 9 ...

... reads:

Should be"

The only drawback with ordering from China is the “free”

Relay Control Panel Module

The Relay Control Panel Module is "out of stock" at the Bosity web page on eBay. Do they re-stock within a reasonable period of time, or is there another source that carries the same or equivalent product?

Relay Control still available....

California Rich,

If you do a search on eBay, you will find similar items....

http://www.ebay.com/sch/i.html?_trksid=p2047675.m570.l1313.TR0.TRC0.H0.XDC+5V+Relay+Control+Panel+Controller+Module+with+Optical+Isolator&_nkw=DC+5V+Relay+Control+Panel+Controller+Module+with+Optical+Isolator&_sacat=0&_from=R40

John from Canada

Reflective optical sensor/detector delay circuit

Do you have any suggestions/sources for time delay circuits compatible with the reflective detector?

Thanks,

Chuck 

Relay Control Substitution

John,

Thanks very much for the link! I found and purchased the alternate parts I needed on eBay.

Rich

Relay Control Substitution with 4 Channel board

See any reason this wouldn't work?

http://www.ebay.com/itm/DC-5V-Four-Channels-Relay-Breakout-with-Optoisolator-/271393856784?pt=LH_DefaultDomain_0&hash=item3f30559d10

Thanks for a great article.  This couldn't have come at a better time as I was researching detection methods for my layout.

Lamar Foster

Signal detectors

Terry,

Could you tell me what brand of signals you use on your layout, that work with the optical system you describe, and where one might purchase them?

Thank you, Jim

Answers to your questions

Wow! Lots of questions.  First, sorry for any typos, no matter how many times you read and reread an article, it seems like something is always missed.

Prof:  It may be possible to adjust a reflective sensor to detect axles, but I don’t think that it would work reliably.  You could paint the axles white to help pick them out from the car undersides, but I don’t think that it’s worth it to mutilate your rolling stock fleet – but if it’s just for a small demo layout, maybe. 

A better solution would be to mount the sensor from the side just above the railhead to try and detect the wheel as it goes by.  The best solution may be to use an interrupter detector to detect the wheel as it goes by.  Mount the detector part of the pair as close to the rail and somewhat above the railhead to make sure that the wheel will shadow the detector as it passes by.  This would be what I would do if I were building something like a defect detector where I wanted to count the axles.

California Rich: You can find similar relay modules on e-bay and Amazon.  Search for something like “Relay Module for Arduino” (Arduino is a microcontroller). A quick search on Amazon using exactly that search term produced the following: http://www.amazon.com/Channel-Relay-Module-Expansion-Arduino/dp/B009T2M012/ref=sr_1_2?ie=UTF8&qid=1399594223&sr=8-2&keywords=relay+module+for+arduino and http://www.amazon.com/Docooler-Active-Channel-Module-Arduino/dp/B00G9TQH8U/ref=sr_1_41?ie=UTF8&qid=1399594373&sr=8-41&keywords=relay+module+for+arduino

Centerpointrr: Subsequent to writing this article, I bought several different versions of these relay modules from multiple sources to test them.  They all have the identical 10 amp relay.  The circuitry is nearly identical with sight variations (for instance, the cheaper ones omit the LED).  So buy any 5V unit by price and you will very likely be OK.  If you plan on using more than one of these, you can buy modules with 2, 6, 10, 12 and even more relays per module and they cost less per relay than buying a single-unit one.

CPLIPRR:  You can use a time delay relay like this one on Amazon: http://www.amazon.com/Power-OFF-Delay-Module-Circuit-SSY-2299/dp/B00F40ONNQ/ref=sr_1_2?s=automotive&ie=UTF8&qid=1399595883&sr=1-2&keywords=power+off+delay+relay The only problems with this is the cost of the relay is somewhat high.  Search for these relays directly from Chinese vendors, they are considerably cheaper.  And all of these that I can find require 12V; so you’d have to supply 12V in addition to the 5V for the detector.  Not insurmountable but a PITA.  Keep reading the next section for a software fix.

fcsw85a: I’m using a cats-‘n-dogs mix of Lionel & Right-of-Way B&O Color Position Light Signals (O scale), that I am rewiring to work with my signal system.  Plus B&O CPLs that I have designed and 3D printed for myself.  Subsequent to writing this article (which was 2 years ago) I have designed and coded a microcontroller-based signal system that will take the output of the detector module directly and the logic produces 6 outputs for bi-directional, 3 color signals.  The software takes care of the dropout delays.  You can find the complete directions of how to build and program the microcontrollers on my LaunchPad for Model Railroading blog here: http://launchpad4mrr.blogspot.com/2013/01/simple-signal-solution.html

The LaunchPad for Model Railroading blog is designed to help model railroaders get into microcontrollers by presenting projects in a step-by-step manner to build and code the LaunchPad microcontroller board.

The question that you didn’t ask.  You can also find substitutes for the sensors, especially if you are going to use a lot of these.  This sensor from e-bay http://www.ebay.com/itm/Lot-10x-Obstacle-Avoidance-Sensor-Infrared-Reflective-Photoelectric-Module-/370848422832?pt=LH_DefaultDomain_0&hash=item565849dbb0  are 10 for less than $16.  They are a completely different arrangement, but the circuit on the board is the same.  So if you can use the alternate configuration, you can save some money.

Some addition notes.  Sunlight (even reflected sunlight) will blind these sensors (the original and the alternate).  So keep them out of sunlight or even intense incandescent light, there’s enough IR content in this light to interfere with the sensors.

Terry

Pros & Cons to the Reflective IR Detector

False positives

Kevin:

That may have been me relating an experience that I had at the 2013 NMRA national convention. See the last paragraph of my answers above.  Strong incandescent and direct or reflected sunlight has enough IR in it to make false positives.  The artificial light needs to be more or less directly overhead.

Terry

Reflective IR Detectors

Would it be possible to connect more than one IR reflective detectors in the same signal block to the same input connection of the relay module so detection is maintained even though one of the sensors is "looking at" a gap between cars, short train, one locomotive only that may or may not be stopped in the block?  The sensors would be wired in parallel to the relay input.

Thank you.

Chuck

Yes, multiple sensors

Chuck:

The short answer is  yes, with a caveat.  If you put multiple sensors on to the input of the relay you need to put a diode in each line coming from one of those sensors.  The reason is that the sensors which are not triggered (high state) will tend to cancel out the sensor(s) which are triggered (low state).  The outcome of this situation are indeterminate, but it probably would not work.

Put a diode in each line coming from a sensor, with the cathode (negative end, the end with the band) towards the sensor.  Any small-signal silicon diode (1N4001 thru 1N4007) should do the trick.  Putting multiple sensors in the block is a good way to eliminate both the inter car-gap and be able to detect a train anywhere in the block.

Terry

IR multiple sensors

Thank you very much, Terry, for answering my Q. re: putting multiple sensors in a block to eliminate car-gap, among other possible snags.  I also want to thank you for your earlier answer re: time delay circuits (written with CPLIRR as ID).  I have ordered the #74447 sensors and #74448 relay modules as well as some time delay relays to get started.  Very enthusiastic on this topic, and look forward to rec'vg. the goods.  Great article by you.  Thanks so much for contributing.

Best to you,

Chuck

Use on Hidden Track

My first thought was to use these in places where the train can't be seen, like long tunnels, helixes, and staging tracks. Then you just have it light an LED on the facia to show that the train is there, and with several detectors along the length of hidden track, you can also see train movement.

Ordering from off shore

Have you encountered any issues with customs on ordering parts off shore?

Thanks

a wiring diagram would be nice

I missed the wiring diagram, although simple, i guess, I still have questions about hookup

Implementing IR block detection and signaling with JMRI

I have successfully got the IR detection working.  It opens and closes the contacts which I will be using with Team Digital SIC24ADs  to control signaling.  I am setting up signal masts and heads in JMRI and am not sure which aspect rules to use.   I have signals with red, yellow and green leds.  I want to simply have stop, approach and clear aspects using the red, yellow or green leds respectively. I have dwarf heads with red and green leds fot the sidings.  None of the Aspect Rules for signaling in JMRI seem to be right for my application.  Any ideas?  I can't wait to get the sinaling working, but JMRI is a little over my head at times.

Thanks,

Lamar

Problem with reflection

I've set one detector up on a test section and had unreliable results.  As stated in the article, on a white card about the best detection range is 1 inch and the detector functions well.  My problem is that I paint / weather all my rolling stock including the underframes and it appears that typical model paints defeat the detector.  There is no reflection from boxcar red, tuscan red, black (gloss and flat), dark greens and rust.  Has anyone had similar experience?  Aside from painting underframes white, I can't think of a viable solution.

Offshore Orders

Hi gnmp,

I used to purchase locally...but all the electronics stores in my area have closed.

Regarding the offshore orders and ebay...

Use a store that has been operating for some time(Volume = security).

Order more than you think you need(Spare parts, Old buddy Frank wants one, etc.).

Search the entire store for useful items and lowest prices.

Bulk order whenever possible to reduce postage.

Allow 3 weeks for customs/mail delivery.