Between the ties IR detector update

[RR_Mel]

This is an update on my new signaling system, I just thought it might be interesting to those using or thinking about using IR occupancy detection.

 

I have been experimenting with the InfraredObstacle Avoidance Proximity SensorsModules, FC-51, for between the ties occupancy detection for a several months.  After running many many tests for the last two weeks I can say that the FC-51 Module will work very good as an HO scale between the ties Occupancy Detector.

 

The advertised specifications of the F-51 leaves a lot to be desired.  It is listed with a detection range adjustable from 2cm to 30cm.  My testing found out of 50 modules the longest detection range is less than 8CM with the potentiometer at max sensitivity.  They are very good up to about 4cm out of the box. 

 

The 5mm sensors are too big to fit between the ties so by replacing the 5mm sensors with 3mm they will fit easily between Atlas Code 83 ties.  After replacing the 5mm sensors with 3mm the sensitivity increased by almost double, the 3mm sensors work reliably at 7cm.  I figured the 3mm emitter had more power than the 5mm but both the 3mm and 5mm draw the same amount of current, 30ma at 1.3 volts and should have the same output.

 

For the FC-51 module with the original 5mm sensors to fit between the ties it would require a 3/16” x ½” slot between the rails.  By replacing the 5mm sensors with 3mm sensors that changes the width to 5/32” (.156”), slightly larger than the space between the code 83 ties (.136”).

 

I have wire extended the sensors to 15’ using #28AWG ribbon cable without any problems.  The picture below has a 4 conductor cable for my testing but the sensors share the ground and 3 conductor ribbon cable works fine.

 

 

With the 3 conductor ribbon cable the FC-51 with the 3mm sensors have a working range of a little over 4” at max sensitivity.

 

It is much easier to drill two holes rather than elongate a hole.  Well OLD shaky hands Mel can’t handle drilling accurate holes between the ties so I made a drilling jig.   

 

 

I drill one hole then turn the jig 180° and drill the second hole.  Works pretty good, I’ve drilled about ten holes all work perfect and that’s saying something for old shaky hands.  The holes at 12° puts the focus point at ½" above the rails.  It catches axles when rolled over the detectors.

 

 

 

I’m down to doing the installation, I have worked out all the bugs and the FC-51 modules feeding the Arduino MEGA drives all eight block signaling system very well, much better than I expected.

 

Considering the cost of under 50¢ each and another 10¢ to 15¢ for Mel Mods they are still the lowest cost detection out there.

 

By using steering diodes a single FC-51 can be used to drive more then one device.  

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

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

 

[Carolina Northern]

Mel,

 

Thanks for the update. I've been playing with these detectors for a while. 

My big order (50) and the 3mm sensors had just come in when I had some unexpected surgery. Doing fine, but had to back off on development for a while. Still not supposed to be under the layout. So very interested in your progress.

The drill jig looks like a big improvement over what I was doing. I had a few failures in my hand drilling. At the time, I was trying to use the original sensors with some extention cables. Have to see if I can build one when I'm allowed back in the shop.

Will be following along, keep the updates coming.

 

thanks,

 

Don

 

[SPSOT fan]

RR_Mel

 

 

Completely off topic here, but Mel, I had to look twice to figure out that those pictures of your track was a model. Yes, I recognise that Atlas Code 100 track, but you balast looks so realistic, I almost thought it was real. That small green moss bits look amazing. Good job, and sorry for going a bit off topic!

[RR_Mel]

Carolina Northern

Mel,

 

Thanks for the update. I've been playing with these detectors for a while. 

My big order (50) and the 3mm sensors had just come in when I had some unexpected surgery. Doing fine, but had to back off on development for a while. Still not supposed to be under the layout. So very interested in your progress.

The drill jig looks like a big improvement over what I was doing. I had a few failures in my hand drilling. At the time, I was trying to use the original sensors with some extention cables. Have to see if I can build one when I'm allowed back in the shop.

Will be following along, keep the updates coming.

 

thanks,

 

Don

 

 

I believe my best find was that the 3mm sensors greatly improved the sensitivity of the FC-51.  The 5mm sensors that come on the board didn’t respond nearly as good as the 3mm do.  The 5mm didn’t see a axle rolling across the sensors and the 3mm will see .03” rod.

 

Last evening I tried drilling a pair of holes in deep scenery below the roadbed, I used the shorty 3½” drill first then a 12” drill and it went well through two layers of plywood about 2” apart plus about 2” of scenery.

 

I don’t want to used delays in my design so on my viewable mainline I’m going with 6” spacing between sensors.  That will catch even my smallest locomotives without any delays.

 

The FC-51 is pretty fast, using a counter on the output and a blackened flywheel on one side it will count the RPM to over 1K.

 

I can’t crawl under so I do as much as possible from the top of my layout.  All of my viewable mainline is within 12” from the edge of my layout so installing the between the ties sensors is fairly easy.  In my hidden areas I mount the FC-51 modules for the curves overhead on ⅛” crafters foam board.  I have some existing beam break optical detectors for long straight runs for my hidden track.  One beam break will cover 12’ of straight track.

 

I use Telco plastic type “D” rings around my layout for wire management and using #28 ribbon cable really helps keep things from getting out of hand.

 

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

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

 

[RR_Mel]

SPSOT fan

 

 

 

 

 

 

Completely off topic here, but Mel, I had to look twice to figure out that those pictures of your track was a model. Yes, I recognise that Atlas Code 100 track, but you balast looks so realistic, I almost thought it was real. That small green moss bits look amazing. Good job, and sorry for going a bit off topic!

 

Thanks for the good words.  That ballasting has been down for about thirty years, aging helps.  It’s going to make it hard to disguise the new sensors.

 

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

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

 

[rrinker]

 WHen I was looking at the Dallee site for the DC trolley thread, I noticed they have a rather interesting IR sensor they use in their turntable indexer - seems to be able to detect the width of a paper clip. I wonder what the actual part number of that is, and how much it costs from a regular electronics distributor. It's the one peice type, instead of a separate emitter and detector.

                                       --Randy

[RR_Mel]

rrinker

 WHen I was looking at the Dallee site for the DC trolley thread, I noticed they have a rather interesting IR sensor they use in their turntable indexer - seems to be able to detect the width of a paper clip. I wonder what the actual part number of that is, and how much it costs from a regular electronics distributor. It's the one peice type, instead of a separate emitter and detector.

                                       --Randy

 

Randy

 

I use a Mel built IR indexing system on my 135’ CMR turntable.  I have a sensor on each end of the bridge (paralleled) pointed to the pit wall under the center of the rails.  I use an emitter behind the pit wall looking through a 1/16” hole centered under the track.  I turn on the emitter I want the bridge to stop at and it is accurate to about 1/64” at the rails from either direction.

 

The most difficult part was making a slip-ring for the emitters and bridge lighting. 

 

 

 

I have never liked using the pit rail for track power so I went with a .015” brass rod “over head power drop” for one rail and the drive shaft for the other.

 

The power pole is K&S brass tubing.

 

 

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

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