Automated semaphore signal

It occurred to me recently that there are no semaphore signals on my layout, they're all colour light ones.

So I started hunting around for some electric semaphores to add to the layout and acquired a single arm signal, which then required automating (obviously)

Now normally I would use the same method that I used in the station by using the dead sections in the points but for this one there are no points nearby.

Time for some modification...

I used a standard piece of straight track and cut away sections of the third rail either side of one of the rail fixings. This gives me a small section of isolated rail, which I was then able to solder a wire directly under the rail fixing. The isolators either side were taken from a broken piece of isolating track that I had spare. The fixings either side of this were then wired together to allow continuity through the track. Finally some PVA glue was used to secure the rails. It dries clear and is hard to see.

So I have an isolated rail section for a trigger and an electric semaphore ready for fitting. Now I needed a control circuit.

Having recently made the colour light signal controls using a transistor & capacitor arrangement, I used the same principle for the semaphore. The main difference this time is that colour light signals require a constant power supply to either lamp. The semaphores need only a brief pulse, just like the points motors. So for these I combined a timing circuit with a capacitor discharge circuit (same as the points) then it was time to fit the signal itself...

First thing that struck me was just how big these things are, especially when compared to the colour light versions. The mounting base is massive!

After some tweaking and a bit of foliage around the signal base, it now  blends in a little better.

Next project is to fit a home and distant signal by the TPO set, which will wire into this one.

It looks and operates really well.