Automated Signals for Free-mo (Infrared Detection) - Part 3 of 3

Here is the wiring to take the signals from the infrared sensors under each track and also to power the dual signal heads:

I am pleased to report that the system works as designed. Here is a shot of the signal masts:

These masts are mounted on one of the Free-mo modules in my basement layout. I have yet to build any individual dedicated Signal-mos. Once I have done so I shall post pictures.

Automated Signals for Free-mo (Infrared Detection) - Part 2 of 3

 Other components of my signalling system include:

Signal Masts

As with my last signal project described in December, I again made my own signal masts using the same jig described at that time. However, as can be seen in the above picture each mast is double-headed to accommodate signalling in both directions (in my earlier project I used two separate single-headed masts to control traffic in each direction). Since this project is signalling for double-track Free-mo mainline I need signals for both directions for each track so double-headed signals made for less complexity.

Unlike my earlier signalling project for which the signal masts are permanently mounted on the layout, for the Free-mo signals, I wanted a method of making the signal masts removable so they can be stored and transported separately from the Signal-mo modules to lessen the chance of damage.

In the above picture, the grey-coloured base was 3D printed with snug-fitting mounts on which the signal towers fit. The box with the green, yellow and red stripes fits over the signal masts and is fastened shut with Velcro.

Signal Mast Mounts

The grey component is 3D printed to accept a 10-pin female receptacle.

The above picture shows the receptacle mounted in a module. It is fastened with screws from the underside. The bottom of each signal mast has a 3D printed base in which is mounted a male 10-pin connector which plugs into this female base.

Here is a signal mast mounted on the base.

The 10-pin connectors at the bottom of each signal mast are wired as follows:

The red, yellow and green connectors on the left are wired to the three corresponding colour LEDs facing one direction. The other red, yellow and green connectors are wired to the LEDs facing the other direction. The two white connectors are wired to the shaft of the signal mast which is made of brass. The anodes of all the LEDs are wired to the mast. It is important to note that different colours of LEDs draw different amounts of current. Therefore, in order to ensure a comparable brightness of all LEDs I did a bit of experimentation and wired different strength resistors in the wires to each of the different colour LEDs.

The wiring configuration described above means that it doesn't matter which way around a signal mast is mounted - the same contacts will light the same LED colours regardless of which way around the signal mast is mounted.

IR Detector Mounting

My last blog post described the infrared detectors that are to be mounted between the rails. These need to be mounted in place.

The two receptacles for the signal masts are made to fit in a 3/4 inch hole. The holes between the rails for the IR sensors were made using the high-speed hole saw pictured above.

I 3D printed the above fixture which is used to hold the IR sensors in place from beneath the module.

The picture above shows the two signal tower receptacles mounted under the module on the extreme left and the right of the picture and the two IR sensors mounted in the middle. The wires at the bottom of the picture have nothing to do with this project.

I put a thin layer of Flex Paste around the IR emitter and sensor. Flex Paste is one of the "Flex Family of Products" advertised by that very annoying man on TV. What I like about it for this application is, by soaking a Q-tip in isopropyl alcohol one can easily remove excess material and smooth the leftover surface.

This shows all components mounted in the module. I still need to add some ballast to cover the white Flex Paste. When this picture was taken the IR emitter was powered up - you can tell because a digital camera is sensitive to infrared light (tip - if you want to see the infrared signals coming from any such emitter, such as a TV remote control, simply turn on the camera in your smartphone and point it at the output window of the remote and active the remote control button - very handy if you aren't sure whether the remote isn't working only because of a dead battery or because you dropped and broke it!).

Automated Signals for Free-mo (Infrared Detection) - Part 1 of 3

Happy New Year! I don't think I have ever felt so good about the start of a new year as I feel now.

In December I posted a two-part article that described the design and construction of my automated signalling system which used block detection to identify the presence of a train. The system continues to work flawlessly.

In earlier posts, I have mentioned my participation in Free-mo (see January 27, 2019 post which explains Free-mo model railroading and March 21, 2020 post which explains that the middle level of my home layout consists of Free-mo modules). I have seen working signalling systems on a Free-mo set up at the Big Valley Alberta event which is hosted by the Calgary Free-mo group and where I found that the added realism makes for a good experience.

I decided that it would be impractical to employ block detection to signalling for Free-mo for the following reasons:

• Free-mo modules are designed and constructed by various people. Modules can be short (say 2 metres) or long (say 30 metres, in multiple sections). In my experience, most are 2 to 4 metres in length. While the Free-mo standard must be followed for the main buss wiring, this does not mean that the wiring to a module has been designed in such a way that a detection circuit could be installed easily without redoing a lot of the wiring. If a person is reluctant to redo their wiring then the signalling system would be frustrated by one module being "dark".

• Even if a local group of Free-mo modellers agreed to make the necessary modifications to all of their modules to accommodate block detection, one of the benefits of Free-mo is for people with Free-mo modules from other locations to be able to join the group. Since their modules would not have been modified, their modules would be "dark" for signalling purposes.

• The design of my block detection signalling system placed signal masts at each end of a block. Say if one were to go to the trouble of rewiring all Free-mo modules for a local group there would need to be added a huge number of wires under each module (with an equal number of reliable connections between module sections) to mount signal masts at the end of each module. The wiring of Free-mo is extensive enough without adding many more wires to the mix. This point only refers to the wiring under each module - also, there would need to be wiring to allow the system to communicate the presence of trains to each adjacent module which adds even more wiring.

I decided that the more practical approach would be to make use of dedicated signal modules "signal-mos" on which the signal masts would be mounted. Each signal-mo would be one foot long and would conform with the "mini-mo" supplemental standard published by Free-mo.org. A mini-mo can be narrower than the normal Free-mo standard but I decided that a layout would look better if the signal-mo is the same width as the adjacent modules. Since the signal-mos would be used on mainline track this means a 26-inch signal-mo width and double track.

All wiring related to the signals would be mounted underneath the signal-mo. The only wiring leading from a signal-mo would be a 6-conductor flat "telephone-style" cable connecting the signal-mo with each adjacent signal-mo. Aside from the normal buss wiring for all Free-mo modules, there would be no other connections to adjacent modules.

The presence of trains would be detected with the use of an infrared detection device which looks like this one which I purchased from eBay:

In this photograph, the device is sitting atop the smallest-size Post-in-Note pad to show scale. One of these would be mounted underneath the centre of each track on each signal-mo. The trim-pot which has an X-shape is used to adjust the sensitivity of the infrared detection. One of the "LED" devices on the left is an infrared light emitter and the other is an infrared light detector. When a train passes over the sensor some of the infrared light bounces off the underside and is detected. The three electrical leads consist of positive and negative leads (5 volts DC) and VCC to which is attached a wire leading to an Arduino mounted underneath the track. One Arduino is required for each of the two tracks. The ground wire is also common with the Arduino.

How the Signals will Operate

The following depicts how the system works without showing any of the electronics or wiring:

Some key points:

• Two-track mainline; the trains are travelling in the same direction that seems to be conventional "normal" travel when there is a double-track mainline (perhaps those in the UK, Australia, Japan, etc. follow a different practice because they drive their cars on the other side of the road from those of us in North America, Europe, etc.).
• The rails coloured white for each signal-mo (each of these would be 1 foot long and 26 inches wide). The rails coloured grey depict all other Free-mo modules (anywhere from 1 foot to infinity in length and 26 inches wide at module ends).
• When the train on the lower track passed over the last signal-mo, the IR sensor mounted under the track triggered the backward-facing signal to show red, protecting the train travelling in the module to the right. This same signal-mo tells the adjacent signal-mo to the left of the occupancy so that signal turns yellow as a warning to approaching trains and the requirement to slow down.
• The engineer of the train on the lower track sees a green signal because both the next module to the right and the one after that are unoccupied.
• The same principles apply to the other track and also work the same way if the trains were to be operated in the opposite direction.

What a Signal-mo consists of:

Wiring

The following diagram depicts the wiring mounted underneath each signal-mo:

To wire this under each person's individual module along with all of the other wiring and hardware that is under there would quickly become a nightmare.

The following diagram shows the signal-mo with the 6-conductor flat telephone style wires that take signals to adjacent signal-mos:

Complete Picture

Finally, here is a diagram of the complete picture with only one of the signal-mos showing its wiring:

 

Coming up - my next post will explain the construction and assembly of the various "real-life" components.