Sunday, October 10, 2010

Thanks Geoff!

For those that have been following my blog, you will remember that I’ve been looking at implementing my staff system around Cassino that will use green and red LED’s located at the end of each crossing loop (on the facia of the layout) to represent the staff machines in each signal box. Being an electronics simpleton, I just started with two double pole double throw switches and thought how I needed to light the Red and Green LED’s and thought that I’d use the two sets of contacts on these switches for this.  This was how my trial staff machine was wired from a couple of weeks ago.
How I wired my original Block Switches.

However, this method that I designed had its drawbacks in the number of separate power supplies required to make it work – 4 power supplies. When you tried to run two Blocks off the initial four power supplies, you got feedback and this caused multiple (read all) the LED’s to light when, certain combinations of switches were set.

I had then just redesigned my signal box – to include Integrated Circuits (IC’s) to then use NOR and XNOR logic chips, fairly easy to wire, and then drive the green and red LED’s via a driver circuit. I was readying my shopping list from Jaycar for the weekend, when Geoff from "Splitter's Swamp Creek" (it's probably a torrent with all this rain we are having) made me feel very small. He sent me a copy of an article in the September issue of Model Railroader. Now if I had not been on holidays lately when that particular magazine did the distribution rounds at work, I would have known this. What are friends for – they just skipped me from the distribution list – Thanks PK – Mate!

Well back to Geoff! After reading the article I went – Doh! Mr Burns had solved the problem. Well actually the article solved the problem. Geoff just showed me the article.  By wiring the first DPDT switch in one signal box in a reversing fashion and sending the output from that switch to the next reversing switch at the other end of the section in the next signal box and the output of that switch controls the red and green LED’s back at both signal boxes, with the LED’s wired anode to cathode and Voila! The lights magically switch back and forward between green and red and green and red, as a switch is toggled. It does not matter what switch is changed, the LED’s just reverse. I have no idea why I did not think of that myself – Oh I know – I’m not an electronics guru. I’m sure there are many people out their reading my blog that knew this all along and some people had no idea how I had stuffed up my design and needed 4 power supplies – but it was logical to me at the time.  Here is how I will do it now.

How I now intend to wire the block switches now

I guess it is just another example of our Blogs that we follow, providing a method of communication and the opportunity for people to share information for the betterment of the hobby.

Our last Tuesday Nighters’ meeting had 10 people attend. Discussion was very enthusiastic about everyone’s recent holiday stint, and progress on layouts or activities involving staff machines. Certainly lots of laughs were had and mostly at my expense. I gave a comical recount of my trip to the hobby shops in Sydney and the characters I met and Peter talked about his trip to the Sydney AMRA Exhibition.  He also made us feel very envious as he picked up a bargain at the Austrains stand.

While on the subject of staff machines, at the Tuesday Nighters’ Meeting, Darren from "The Nimmitabel Extension" brought along his version of how he was going to implement his staff machines – maybe he will update his blog with pictures soon. Darren has always had a desire to have operationally correct infrastructure, staff machines, signalling, track layouts, etc. But for his staff machine implementation he was going to use voltage meters on his facia with an inlay behind the needle saying Line Free and Line In-Use. Darren was also using switches just like mine – just a different type, and when the power is sent along the circuit, the metre moved between the two positions of the staff machine display – In-Use or Line Free. Pretty Good!

I pretty full on week this week. Commonwealth Games on at night, Boss’s birthday – no I did not give here a new train, as PK says I like my macadamias. I did have George come over for a visit on Friday night, and a day at the Club on Saturday.

Today I cut out the 19 signal box facia panels and installed the relvant switches into the first 10 panels.  Nothing wired yet though.  Some of my panels will be for intermediate staff machines located in sidings within the section.  So it will be possible to put a train away into a mid section siding and also have the train get right of way to leave and head to one of the ends of the section.  I just put a third or fourth double pole switch in the section and wire it up like the second.  I also laid the first run of cable that will carry this signal box logic and between the double pole switches located at each end of the loops.  So this cable went south from Acacia Ridge to Glenapp, The Risk, Border Loop, Kyogle Stock Siding, Kyogle, and Fairy Hill until I ran out of cable.  Fairy Hill Loop can be controlled from both sides of the baseboard so I will have a panel on both sides of the layout.  Each panel will be located adjacent to the signal box in each loop.

The next Tuesday Nighters’ Meeting is at my place and I have promised that I will try and have some of my staff machines in operation for three loops on the top deck. Darren will also bring his wireless NCE controller over so he can practice driving a train. Jacko was also going to bring some 3’ 6” stuff. So I need to connect up a controller to my 12mm track, and as Jacko is from the old school, it won’t be DCC’ed so I need an old DC controller installed. Unless I wire a spare NCE decoder, with its red and black wires to my 16.5 mm track and the orange and grey wires direct to the 12mm track voila – a poor man’s decoder install for any non DCC’ed loco.

See you next week.


  1. CM, re being an electronics simpleton, can I join the club?

  2. Hi Craig,
    Well done on getting the info you required. Your spot on regarding shareing info between blogs etc. If and when you go to see Mr Jaycar ask them about the Red/Green led in one. As you change polarity it changes from red to green or visa versa.

  3. Glad I could help Craig. You've got it right about the Blogs, it's almost like an online modelling club...well actually it is! See you Tuesday!