9 Mar 2012
Goodbye to the old test track
Back in December 2006 I decided to build a model railway. I decided as things had moved on som much since I last did model railways I would build a test track. A single bench about a meter high was built to test out DCC and the like. Subsequently in March 2009 I expanded that to a circuit on three benches and integrated that over the following year with block detection, computer control, automatic signalling etc. etc.
But it has outlived its usefulness and this photo was taken at the start of the week before I salvaged what I could from it in components and wood. It has now gone completely.
PIC}:-test layout;
One of the main things I (re)learnt was that if you want to do occupancy detection and so on the wiring becomes and absolute mess unless you work really really hard to get control of it. As I knew the test layout was never long term I made no real effort to control it and as a result it became quite a shameful pickle.
The new layout is much bigger - consuming a room of 7.5m by 4.5m and has over 40 points - a number of which are slips requiring two point motors. Accordingly the wiring needs much more thought.
I have decided that each of the major areas will have one or two control boards on which PCBs etc. are mounted. With connectors back to a main power distribution board which distributes DCC track power (via a Digitrax PM42) and also other power supplies required for running the various circuit boards.
My first control board is now finished, it has no signalling element on it as it is for a non-scenic part of the layout. It has been tested and operates correctly showing track occupancy and operating point motors. I wanted to get this working before I tore up the test layout in case that contained any lessons on how to wire the various devices.
The control boards (I think there will be 6 or so) are designed to hang underneath the layout, on two simple hooks.
Part of the plan is never to have to do the dangerous sport of upside down soldering!!
4 Mar 2012
A diversion into Railbus DCC fitting
As proof that I don't learn from my mistakes - I am an absolute sucker for new models. The rational part of my brain tells me it will mean frustration and expense but that never seems to get control when something nice appears on the website of my favourite Internet retailer.
The latest example of this is the lovely looking Heljan railbus in dark green with speed whiskers. Ordered it on a whim earlier this week and as soon as it arrived I attempted to convert it to DCC.
It is nicely packed in the standard Heljan box, it is also a wonderfully heavy model - there is a real heft to it.
To fit the DCC decoder, the first job is to prise off the two airhorns - to reveal two fixing screws - it is quite hard to do this without damage - I found a scriber was the best tool.
The hardest job then is to remove the top half of the body - note the instructions in the box do not mention that you MUST carefully remove one end of the two metal hand rails or when you split the body they will fly across the room.
You have to prise the bottom of the doors away from their seating and slightly outwards to allow the top to come off - this is really hard to do without damaging the bottom of the door (which you can see from the phot I did despite using the recommended tool of a scalpel).
Then undo the little plastic keeper plate that runs the length of the body by undoing two crossheads that hold it down.
Now you can gently lift up the centre circuit board which holds the DCC decoder and remove the dummy board. BE VERY careful - the wiring to this board is incredibly delicate and if you pull one off the metal roof that many disappear into it is impossible to repair them (I speak from experience).
Now you can fit a decoder - here is a TCS621 which seems to work ok. Note that (at least in theis case) the decoder needed to be inverted compared to the dummy board. 
Here is my disaster a broken red wire that I was unable to repair - argh!!! return to sender!