Electrical Basics of the Layout

The layout is wired using the wire bus method - two main heavier gauge wires running the whole length of the layout, with smaller gauge wire coming off the heavier wires at strategic points on each module, and connected to the track.

The layout is controlled by a ROCO LocMaus 2 based system, with a 2.75amp booster. This allows me to easily run about 4 locos at a time. The layout currently has 2 hand held tethered throttles, which are connected via RJ12 cables to the booster's master and slave port. The ROCO system I use allows the addition of a number of extra slave controllers.

Most points are self isolating Peco Insulfrog turnouts, and so very little had to be done to make the layout DCC compatible. But there was one point, a Shinohara, which required a little extra wiring and a Single Pole Double Throw (SPDT) switch to stop shorts across the frog.

There is also a Double Pole Double Throw (DPDT) switch which allows me to switch between a DC controller and the DCC system. Not that I really use it, but it seemed a good idea when I used to run the occasional DC loco on the layout, and so I have left the switch there, just in case.

Top | Back to C&SFT Index

DCC Voltage Regulation

The DCC system I use to operate the layout has a rather higher track voltage of around 26 volts AC. When I operate the layout without any voltage regulation, I find that most of the decoders I have, which are single function decoders, cannot have their highest speed set using the ROCO LocMaus 2 system. At the high track voltage it is also hard to control the lower speeds that I need while shunting. So I felt I had to control the maximum speed of my locos and a drop in track voltage seemed the most logical choice to achieve this.

I found an article in the Aug 2004 issue of "Australian Model Railway Magazine", which put forward the idea of using diodes to bring the voltage down to a more reasonable level. From information in this article I decided it best to check the track voltage of my layout, which is when I found out it was around 26 Volts. The article also mentioned that a voltage that is too high can cause heat stress on decoders, so I felt I needed to do something about the problem.

I built a diode matrix, as shown in the graphic, and installed it on the layout. The matrix can include just a single pair of diodes on each wire, or can has as many as 5 pairs (the amount I have), depending on how much you want to drop the track voltage of your system. My track voltage through the diode matrix is around 18V. And even the most hard to control loco I have is a nice smooth runner at 18V. You need to use FAST RECOVERY RECTIFIER diodes. They need to be fast recovery so that they do not interfere with the DCC signal.

Advantages & Disadvantages I have noticed to having the Diode Matrix to lower the voltage:

* Advantage: If your locos make that awful whining at 26V, it is much less noticeable at 12 or 16V.
* Advantage: All locos run much more smoothly.
* Disadvantage: Locos seem to stall more on dirty track, or if the loco's wheels are dirty. How to fix this: Run your trains more often!

Top | Back to C&SFT Index

Motorized Turnouts

Electrically, all the turnout motors have a common return back to the control panel, where there are SPDT or DPDT switches, connected to Momentary On Push button switches. The plan is to use the DPDT switches to provide signal power too, allowing an easy way to see if points are set properly for any particular train. As at May 2007, I have motorized all except one that I planned to motorize.

I had planned to buy and build a Capacitor Discharge unit to the turnout motor power circuit. And I still might do that... But I found an interesting way to power the turnout point motors. Originally I used a 13V Automotive Battery Charger. But I found the turnout motors were not always responding well, and sometimes they were very noisy. Some time ago I had to purchase a new power supply for my wife's laptop computer and I noticed that the output voltage on the laptop power supply was 19 volts and about 4 amps - I thought it was worth trying a laptop power supply if I could find one cheap enough. Then in May 2008, a friend of mine noticed a laptop power supply with a 19V and 3.16Amp output in the local 'opportunity shop' with a price tag of $1.00! He got it for me, and I tried it on my layout - the turnout motors stopped making most of their noise, and every point motor worked without a hassle. It puzzled me a little why the DC Battery Charger rated at 8 amps would not power some of the point motors where as a 3amp power supply would. Here is my theory:

• I think the Laptop Power Supply is AC, not DC. I beleive it is recommended that AC be used for point motor power.
• A Laptop Power Supply is rated to give the same power output constantly, whereas a DC Battery Charger is really meant to be a trickle charger.
• The fact that the Laptop Power Supply is 19V compare to the DC Battery Charger being 13V probably makes bit of difference too.