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!).