NEONS Power Systems
by Steve Gillett

For many years the N-Trak club to which I belong (NEONS, the North East Oklahoma N-Scalers) kept its head in the sand when it came to DCC. Because very few of us had decoder equipped engines, we both resisted and avoided it. However, as DCC became more and more commonplace and our members began to acquire and/or convert some of their locomotives to DCC, it became clear that we needed get with the program, move into the 21st century and get some of them thar new-fangled DCC thing-a-ma-jigs for both our permanent layout and our show layout.

Our first decision was to select Digitrax as the manufacturer of choice since their equipment was used at most shows we attend. NEONS has a very large travelling layout plus a small, 8-module layout that is semi-permanently set up at our sponsor’s train store. The store layout benefits both our club and our sponsor since it allows club members to run trains whenever the store is
Power System on Store Layout

Figure 1 - Power System on Store Layout

open and provides the store with a place for customers to test new or potential purchases. This store layout was powered by three MRC Tech II Railpower 2500 power packs (one each for the red, yellow and blue lines.) We added a Digitrax Zephyr DCC system and built a panel with three toggle switches, thus allowing operators to toggle between DCC and the assigned DC power pack on each of the three lines (See Figures 1 and 1a).

Power System on Store Layout

Figure 1a - Power System on Store Layout

Early research and experience by clubs across the country led to a few rules of thumb. The first and most critical rule is that a Digitrax power distribution line should never extend more than 50’ in either direction from the power source. The longer the distribution line, the more resistance there is, and the more the signals degrade. Because our show layout loop is usually between 150’ and 240’ long, we decided to break our layout/loop into three blocks and locate a power supply near the center of each block so that the distribution lines never exceed the 50’ guideline. We initially installed Digitrax equipment only on the red line of our travel layout so we could tie into the Red Line Route™. The other two lines remained powered with Aristo-Craft wireless DC throttles. Eventually, the flexibility we became used to on our store layout led us to develop a similar system for shows.

Since we nearly always link up with other clubs at shows to form a multi-loop layout using the Red Line Route™ format (which is exclusively Digitrax DCC), we only need to offer the choice of DC / DCC on the yellow and blue lines. (The NEONS do not have the mountain line on any of our modules.)
Power Box Top & Front View

Figure 2 - Power Box Top & Front View

Power Box Bottom View

Figure 3 - Power Box Bottom View

Using the North Raleigh Model Railroad Club's design as a base, we constructed three custom power boxes, each with a Digitrax 8 amp DB200 booster, a Digitrax PM42 to split the DCC power to the Red, Yellow, Blue and Green lines, two UP-5 loconet interconnects, and two Aristo-Craft DC analog power receivers and antennas that receive signals from our Aristo-Craft wireless remote throttles. Each box is powered by a Digitrax 2012 20-amp power supply that feeds the Digitrax and the Aristo-Craft units and also has two wall warts, one for the PM42 and one for the UP-5s. In order to protect the power equipment and all engines on the layout, each of the three units in each box (two Aristo-Craft receivers and one Digitrax DB200) is fused on both the inlet and outlet side. We keep a large supply of fuses just in case! (Figures 2-8 and Diagrams 1-4).

Power Box Bottom - Left Side

Figure 4 - Power Box
Bottom Left Side

Power Box - Bottom - Right Side

Figure 5 - Power Box
Bottom - Right Side

Power Box - Bottom - Doors Closed

Figure 6 - Power Box
Bottom - Doors Closed

Power Box  - PM42 - Front View

Figure 7 - Power Box
PM42 - Front View

Figure 8 - Power Box - PM42 - Top View

Figure 8 - Power Box
PM42 - Top View

Diagram 1 -- Power Box Schematics - Top View
Diagram 2 -- Power Box Schematics - Front View
Diagram 3 -- Power Box Schematics - Bottom View
Diagram 4 -- Power Box Schematics - Doors
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Master Command Station - Front View

Figure 9 - Master Command Station
Front View

The DCC equipment in all three power boxes is controlled by a Master Command Station. This unit contains a Digitrax DCS200 8-amp command station, an LNRP loconet repeater and our old Aristo-Craft 10 amp power supply. It does not power any track, but functions as the brains of the system. Its only connection to the layout is through the Loconet bus and a ground wire. If we link our loop with others to form a multi-loop layout, we can either use our Master Command station, or disconnect it from the loconet and use the host club’s equipment for that task. The Master Command Station also contains a programming/test track and a wheel cleaning tool. By toggling a switch, the 17” long track works as a programming track or a test track. Even though the DCS200 doesn’t power a block of track, we use an 8-amp unit here so that if one of the boosters fails, the DCS200 can do double duty as the Master Command Station and supply power to one block. An old-style beginner transformer powers the wheel cleaning tool. (Fig 9-12 and Diagrams 5-8)

Master Command Station - Top View

Figure 10 - Master Command Station
Top View

Master Command Station - Bottom View

Fig 11 - Master Command Station
Bottom View

Master Command Station - Bottom - Door Closed

Figure 12 - Master Command Station
Bottom - Door Closed

Diagram 5 -- Master Command Station Schematics - Top View
Diagram 6 -- Master Command Station Schematics - Front View
Diagram 7 -- Master Command Station Schematics - Bottom View
Diagram 8 -- Master Command Station Schematics - Doors

Ground Connection and Aristo Antenna Connection

Figure 13 -- Ground Connection and
Aristo Antenna Connection

Each power box is 9” deep and 30” long so it can be clamped on the back of any module, including a corner module. The Master Command box is 18” long. At the back right corner of each box is a terminal block where ground wires can be connected. (Fig 13) All equipment in each box is tied to this ground block. We have several spools of ground wire that we use to interconnect the boxes. Even though all four of our power supplies have a grounded 110v plug, only one is connected to the grounding system so that there will be no possibility of a ground feedback loop.

Our radio tower has a Digitrax UR91 Simplex radio receiver and a UR92 Duplex radio receiver to allow wireless control of our Digitrax equipment. The receivers are mounted at the top of the tower so that they are over 8’ above ground to minimize interference and maximize range. (Fig 14 & 14a)
Radio Tower

Figure 14
Radio Tower

Radio Tower

Figure 14a
Radio Tower

There is a separate antenna for each of the Aristo-Craft receivers mounted on the power boxes next to the receiver. Each antenna wire is threaded inside a piece of ½” PVC that sits in a ½” PVC collar attached to the boxes. The wire is connected with banana plugs. The PVC tubes are painted black and look like smokestacks. (Fig 13)

Toggle Switches

Figure 15 -- Toggle Switches

Each line (Red, Yellow, Blue and Green) can be switched between DC and DCC with a toggle switch. (Fig 15) One of the two Aristo-Craft receivers is assigned to the Yellow line and the other to the Blue line. Access jacks are in place to attach a DC power supply for the Red Line and one for the Green line if needed. We rarely do that because we always designate the Red line as DCC and, since we don’t have a mountain line, the green line is normally used as a back-up or to power isolated sidings that have switching operations.

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Another rule of thumb that became an N-Trak recommended practice was to upgrade all the power distribution bus lines under each module from 18 gauge wire with Cinch-Jones connectors to 12 gauge wire with Anderson 30 amp Power-Pole connectors. The NEONS implemented this upgrade on all of our modules. (Diagram 9)
Diagram 9 -- Power Pole Specs

The three power boxes give us six Aristo-Craft receivers, three each for the Yellow and Blue lines. All six receivers are set to the same frequency. Depending on the desires of the operators, we either set each of the three receivers on a line to a different channel so the operator must change channels as his/her train moves from block to block, allowing him/her to operate two trains at a time, or we set all three receivers on the line to one channel allowing only one train at a time but eliminating the need to constantly change channels.

Although this Aristo-Craft operating procedure looked simple on paper, it quickly became a serious problem in practice. At times, a train uncouples. When this happens, the operator reverses power, backs the train up, reconnects, reverses power again, and continues on. Unfortunately, since our power boxes are distributed around the layout, all three Aristo-Craft receivers serving that line don’t always receive and process the power reversal signal. This sometimes results in reversed polarity at a block boundary and when an engine crosses that boundary, there is a short, the train won’t move, and sometimes wheel-sets are melted (which is another reason for the fuses!) Also, when more than one train is running on a DC line, there can be other problems. Not all engines require the same amount of power to move at a certain speed. As a train enters a block, the operator must switch his/her throttle to the new block and adjust the power level so the train maintains the proper speed. Failure to do this will cause a train to either slow down or speed up at each block boundary depending on what the power requirements of the train in front required.

At a recent trains show, we discussed our DC and DCC problems with our favorite Digitrax Booth Buffalo. After a thorough review, it was suggested that we really didn’t need to break our loop into the three blocks. Since all of the NEONS modules have 12 gauge power bus wires with Anderson 30-amp Power-Pole connecters and since we use Digitrax DB200 8-amp boosters, the line resistance is minimized and the power is maximized. The previously mentioned guideline that a power distribution line should extend a maximum of 50’ in each direction from the booster before it will suffer too much power loss was based on a system with 18 gauge wire, Cinch-Jones connectors and a 5 amp unit. With our equipment, we have the choice of connecting each DCC booster to power three or four lines for 50’ in each direction, or a single line for at least 100’ in each direction, and even further if it is a continuous loop.

By simply designating each of the three power boxes to serve a single line around the entire loop, one for the red, one for the yellow and one for the blue, this new format was implemented. The only modification we had to make was to increase the maximum power allowance on each sub of the PM42s. This also solves our DC problems since, in this arrangement, only one Aristo-Craft unit serves each line. Now, when two trains are running on a DC powered line, the faster train will occasionally have to divert to siding that has a power on/off switch and wait until the slower train gains a little ground.

Our DCC problems also included low voltage on our Loconet system. When we counted them up, we realized that we had over 20 UP-5s connected to the Loconet, and none of them were powered. Our modules do not have the white line bus so we decided that is was less expensive and less work to purchase and install wall warts for each UP-5. That solved the Loconet problem!

All in all, our new power system is now a simple, integrated, plug and play arrangement, with plenty of versatility that allows our members and guests to operate any train on any line, regardless of whether or not the engine(s) is decoder equipped.

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