Looking for Ideas Concerning Infrared and Other Activation Sensors ... for a Monorail

You could isolate a hot rail and connect a current sensing devise. If the monorail is PS-3 there should be some kind of programming built in. There is a thread somewhere on this. I have only run mine in circles and never read the book.

Does it always go in the same direction?

Another "technology" is magnetic.

Place a 25 cent small disc magnet on the lead car.  Then use a pair of $1 magnetic reed-switches (like on door/window alarms) to detect entry and exit from platform.  The entry switch can trigger a latching relay which turns on platform lights.  The exit switch can release the latching relay to turn off platform lights.

A few variations on the theme...

One magnet on lead car, one on last car.  Magnets placed at different "heights".  Then place the entry and exit reed switches at the same location on the platform but vertically offset so that one gets triggered by the lead car entering the station, the other gets triggered by the last car exiting the station.  The two switches set and reset a latching relay as before.

There are even latching magnetic reed switches.  So the switch itself closes upon application of North pole, and stays closed until application of South pole.  So again one magnet on lead car, 2nd magnet on last car but flipped over.  Now the switch itself can carry the current to the platform lights (no external relay needed).  Albeit these latching reed switches are harder to find and can be finicky.

If space is an issue with the traditional, typically glass-enclosed, reed switches, there are semiconductor or so-called Hall sensors that can be quite compact.  These come in both non-latching and latching versions.  They are also in the $1 range.  Again, if using a non-latching version you could drive a latching relay...or if using a latching version you could drive a conventional relay.

The now common Nd or Neodymium rare-earth magnets are incredibly strong for their size and come in all shapes and sizes.  A typical reed switch suitable for this application is shown below along with a typical Hall sensor.  Note there are 3 wires going to the Hall sensor - 2 wires are DC power (e.g., 5V DC), the 3rd wire is the output.  Latching and non-latching Hall sensors look the same.  Obviously a conventional reed switch is just 2 wires which get shorted.  You can probably find pre-wired reed or Hall sensors.

If you go this route you'll pay more for shipping than the components themselves.  Finding magnets in one-sy two-sy quantities can also be a challenge!

F&G RY posted:

You could isolate a hot rail and connect a current sensing devise. If the monorail is PS-3 there should be some kind of programming built in. There is a thread somewhere on this. I have only run mine in circles and never read the book.

My monorail is conventional, not PS3.

Isolating the hot rail and connecting a current sensing device is a possibility.  I believe Dallee manufactures a device like this.   I will investigate with him, thanks.  I may even chat him up at Springfield in a couple of weeks.

Thanks again.

Steven J. Serenska

stan2004 posted:

Does it always go in the same direction?

Another "technology" is magnetic.

 

My monorail will always run in the same direction.

All that you proposed does seem to make sense but, unfortunately, designing and implementing such a circuit is above my pay grade.  Can you maybe point me to schematic of one of these?

Thanks.

Steven J. Serenska

If it's convenient to isolate a segment of one of the power rails I like the current sensing idea if Dallee or whoever makes such a device.  That is, you wouldn't have to mess at the component level if indeed that's not in your comfort zone.  I looked at the picture of the rails and it was not clear if you'd have to cut out metal or if there are the equivalent of 3-rail "insulating ties" or whatever to mechanically join the segments while insulating electrically.  It also seems you'd need one of those unusual lock-ons or equivalent to separately power the isolated platform station segment.

Anyway, if all that is understood and in your comfort zone I recommend that option.

I'd be happy to put together a schematic but putting it all together would require some experimenting, making measurements, tweaking component values, soldering, etc. which can be tedious if not downright frustrating!  I dug up this thread on magnetic activation showing both reed switches and semiconductor latching magnetic sensors.  There's even video showing both "technologies" in action to control lighting in a baggage car.  Kind of backwards to what you have (controlling lighting in the car rather than the platform!).  But it shows the type of component level wiring and such that might be involved if applied to your situation; photo copied below.  

I'd think it much easier to implement the current-sensing method which ought to be do-able at the modular level.

Also, if Dallee does NOT have something suitable, there are a variety of low-cost modules on eBay that can be applied.  I'd have to find a back of an envelope to scribble on but it could probably be done for $5-10.  For example there are $1-2 current-sensing modules that can detect the train is at the station drawing current on the isolated track segment.  Hard to say if using Lego-like eBay modules would be easier than cobbling together some magnetic sensor components.

Stan:

Thanks for all this great info.

I'm afraid we'll need to do the reed switch approach or an infrared sensor ... like this one.  The monorail track is decidedly not like 3-rail track and I'm not sure it's going to be an easy task to isolate one section of it from the rest.

One advantage I do have is that an "under track" sensor arrangement might be possible since 1) the track is upside down so the sensors will really be over the track and 2) the track is above the room lights, there might not be light pollution.

Has anyone ever used the Azatrax products?

Thanks again for everyone's help.

Steven J. Serenska

Your best bet is a transmissive IR detector setup with the emitter on one side of the monorail and the detector opposite on the other side. 2nd best is the magnetic reed switch approach previously discussed.

The MRD1-V ought to work fine for your application.  The emitter and detector are on wires so you can run them to the rails aiming downward at the roof.  Usually the issue with the optical method is spotty or flakey detection of black painted engines or dark colored cars.  But in your case IF that's a problem you could just put a piece of white sticker on the roof and no one would be the wiser!

If you're running conventional you probably want to run the module with a separate fixed voltage supply.  Are you planning to use those 12V DC LED strips for your platform lighting?  If so, that would be a perfect fit as the module can operate from 12V DC.  Then the module can simply switch 12V DC to the platform lights and you're done!

You could do the same by messing with low-cost eBay modules as described in this contemporaneous thread about roll-your-own ITADs for $2-3 or so.  But I only suggest this approach if you want/like to tinker with IR detection itself to engage more with the electronics side of the hobby.

https://ogrforum.com/t...-and-making-your-own

I like the IR emitter/detector set as a beam over reflective use.

  If the detector side is shrouded well, it proved to be more reliable and allowed a greater distance between the detected object and the components themselves. (up to a few feet)

Set into a small tube 1/2"-1" is great, deeper is better. Your IR emitter should have a narrow focus and be inline to aim straight into the tube. Brighter LEDs give more distance and the detectors can be usually be trimmed for sensitivity.

  These circuit are used often in coin-op skill games around lots of flashing incandecent lights, and florescents alike, sometimes mounted within the same cabinet and capable of spotting at least a coin mid air and in motion.

  I didn't "design" emit/detect at all. I tweaked others work, or swapped types to get things to perform better, guided mostly by tenacity; but they are simple circuits and in my experience take well to tweaks as a whole.