Return to Model Railways

Yet more wiring has been done, and it’s nearing completion now. I’ve added in the point control units I got from Heathcote Electronics. I fitted them to the base board using some computer motherboard standoffs I had spare. I did have to very carefully enlarge the holes on the PCBs to fit the screws. I did the same with the CDU. It keeps them off the board, and it makes them a little easier to get on and off of the boards. The standoffs are just screwed into pre-drilled holes on the base board.

I’ve also added in the power droppers for the electrofrogs (the red wires on the left), which meant some VERY careful soldering top-side. ]

Some additional power droppers were added and joined up too, as well as the interconnecting cabling between the boards. Finally, all the cabling for the point motors themselves was added in, and labeled up accordingly.

I knew I needed to get connectivity to the control box I had designed. Originally I’d picked up a little pre-built unit from Maplin, but it just wasn’t big enough. I needed to fit in point control and indication, as well as eventual signal control, so there just wasn’t space on its A5-sized top. I fabricated a new control panel from some 6mm Ply, and some offcuts of the battens I had. Simply screwed together, it does the job. The top of the box was drawn up in Xara, then printed out and stuck on. I drilled out the holes for the buttons and LEDs, but the edges were a bit rough, so I purchased some small LED holders. The switches are fairly well presented anyway so they’re fine (the nut covers the rough edge). Only half of the top edge of the panel is used, the other half will be used for signal control. I probably should have fit the lot into one section, but I’m happy splitting them out.

Connectivity back to the main boards is via two female 25-pin D-sub connectors, and two straight-wired cables. The indicator and point control wires from the point control PCBs end on female 25-pin connectors, so the cables between are just standard male-male.

All told I ended up soldering 49 connections across the lot, plus all the connections within the control panel. Inside is, quite frankly, a mess. The layout didn’t lend itself to any sort of tidy wiring. I did try, but despite my best efforts, it just wasn’t going to happen.

The wiring used within the control box, and from the control PCBs is actually from a leftover section of 25-pair telephone wire. It’s single core copper, so ample to work the LEDs, and I think OK to work the point motors for short bursts.

It has taken me a couple of days working on it to finish all the wiring. First tests, it worked – ish. A few motors were firing opposite to what I wanted, a few LEDs likewise, and some were totally wrong. Fixing them was simple – I just swapped the wires on the PCB! I also found one motor seems to have either burned out, or just doesn’t work. I have spares though, so it’ll be a doddle to swap out.

There’s a few little wiring jobs left to do. The frog polarity feeds need connecting up, and checking they’re the right way round (don’t want any shorts!). I also have a dodgy joint which needs replacing. Other jobs to do include replacing the dud motor, and one seemed to be sticking, but may have freed itself. I could also do with making some sort of base for the control panel, otherwise I’ll only end up knocking out a wire. The LEDs need gluing in properly, as they tend to pop out now and then. Finally, I’ll finish the main track power feed and I might actually get some trains running round the thing!