Cab Bus – March 2011

Using the internet, I tracked down a source of some universal throttle panels (UTP’s).  Despite the layout being wireless, it is useful to have points to connect either the wireless throttle (handset) or a wired throttle around the various parts of the layout.  There are 12 UTP’s on the layout.  I decided to install an LED on each panel to indicate both power available, as well as to be easily found in a darkened room running under night conditions. 

This required some PC board soldering skills, and a resistor, bi-colour LED and a wire bridge to be soldered to each of the 12 UTP boards.  The wire bridge was made from the excess wire cut off from the resistors, and installed so as to ground the face panel of the UTP.

The bi-colour LED bent and soldered in position (centre top)

It has been some time since I have tackled this type of soldering, but having the right tools, including variable temperature iron, quality solder and flux, the job was a breeze.  The only difficulty was viewing the tiny areas to be soldered.  A magnifying headset helped to bring everything into focus and large enough to see clearly. A pair of helping hands (third hands) helped to hold the PC board at the right angle whilst I soldered the components in place.



The added resistor soldered to the PC board



The small wire bridge soldered to the board insie the "U" bracket

Each UTP was then tested by applying 14V AC from the DCC track output to the LED connections on the UTP, and run for about 15 minutes.  It will be powered eventually by the accessory bus, which is really just a second 14V power bus.. Each UTP proved to be a success, no blown diodes, no magic smoke appearing, and no burnt fingers!

UTP in position and the LED working off 14V AC supply

As the length of the Cab bus will be more than 30m, I have powered every 3^rd UTP with a 12V DC 1A power supply.  This provides power to the UTP and all downstream UTP’s until another power supply is plugged in downstream. This will help ensure that the signal from the booster is not lost as power losses occur over the cab bus, particularly when multiple throttles or handsets are plugged in.

The next job is to obtain some 3 pair cable and wire the UTP’s daisy chain fashion from the DCC Control Unit to the last UTP, where the Radio Aerial is connected in.

After evaluating several different systems, I chose the NCE Power Pro-R (radio) 5 Amp DCC system.  Combinations of wireless and wired throttles can be used with this system on the layout. The convenience of wireless and the features of this system led me to choose it as my preferred system.  Having used the NCE Radio system previously on Bill Black’s magnificent Sn3 layout - Vance Junction, I was comfortable with the use and operation of the NCE system on a layout running non-sound and sound equipped DCC locomotives and lighted passenger coaches.

Layout Joists and Track Bus Cabling – January to March 2011

Some 17mm ply was cut to length, and placed across the L-girders at approximately 450mm intervals.  Both decks and the peninsula took over 140 joists, each screwed from underneath at either end through the L-girder.

Once this was complete, then the main track bus wires were run around both levels, the peninsula, and the helix, all from a central point. All bus wiring was done in 2.5mm² building wire (approx 12-13 AWG). Red and black were chosen as the primary colours for the main bus.

A second bus was also run as an accessory bus, twisted and terminated as above, using 2.5mm² blue and white wires to distinguish it from the track bus.

Taking the sage advice of several DCC gurus on the internet, each of the 6 bus branches was twisted about 3 turns per foot, and terminated on a terminal strip using a 100 ohm 1 watt resistor and a 0.1 microfarad ceramic capacitor. Jaycar was the shop of choice, and bulk orders attracted slight discounts for quantity.