Entry posted by richbrummitt
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A lack of posts over the last few weeks has been down to a lack of progress worth sharing. I've spent quite some time trying to get a system of operating the TOUs going over and over the options, trying and failing and re-thinking.
Initially I used wires linked directly from the switches to the TOUs and when these were removed in favour of the lever frame I intended to use some kind of mechanical system and installed a crank arrangement to lead out from the frame.
Servo arms were drilled out and mounted on telescoping brass tubing. This was connected to different control rod systems. The first wire in tube system from Model Signal Engineering was, in my opinion, very poor. There was a lot of clearance in the tube and a large input movement would be required to have any useful output movement once the slack is taken. This is worsened by every curve required. Sadly the movement from the lever frame and crank arrangement is not very large and although by not nearly the same margin the problem was found to exist in higher quality systems marketed as model aircraft control rods.
I had a brief interlude considering servos based on some ideas I found on rmweb3
The servo is stripped of it's control and microswitches with diodes are used to create the end stops. Although they would be cheaper than point motors there would be a lot of fabrication required that I don't have time for and I hadn't figured out how it would be possible to incorporate much, if any adjustment so I did what I should probably have done from the outset; dug deep and bought point slow motion motors.
I went for cobalts because they are slow motion with a long springy actuation and a smaller footprint. I still had to cut them up a bit to fit them in where needed in this baseboard construction that, whilst it seemed like a good idea at the time, I continue to regret.
The thing keeps consuming wire. I've moved the rest of the control to the front of the layout too. It should be possible to see from the photographs that the switches for the uncoupling magnets that I intend to need one day are recessed into the front.
I had to have a good chop about to create access to fit the microswitches in the lever frames. This was not fun. What was worse was that initially I wired them up like am SPDT toggle but the common on a microswitch is not in the middle and so this didn't work. It took me a while to realise why the readings on the multi-tester did not make any sense. I had to unsolder and resolder the connections in these little apertures.
Don't worry: I can hide the mess behind a facia covering of appropriate coloured mount board.
It still didn't work. I checked the fuse and there wasn't one. When fitted I found that it worked and what's more I wired the first motor up the right way around first guess 
The feed is half wave AC provided by using diodes on the connections to the microswitches to avoid adding a further power supply to the layout. This winding on the transformer is shared with the electromagnets, but the power requirements for the point motors is not high and I think there will be enough juice to go around.
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