Power/Controls

Module Mogul - 3



Harold’s tutorial on installing DCC and sound in a Bachmann 2-6-0 explains how to modify the locomotive’s circuit board, and where to solder new electrical connections.



The issue then becomes feeding the new wires from the connections in the boiler out to the tender. The boiler is an extremely tight fit on the drive mechanism. Harold drilled a hole down through the weight in the firebox to provide a route for the wires. I decided to use files and Dremel grinding discs to cut grooves along the top and down the back of the firebox weight for the wires. The six wires include two each for track power, motor leads, and headlight leads. The wires were grouped into the “black” set and the “red” set and fed out of the back of the locomotive below the cab.



Corresponding wires were fed forward in the tender, exiting through the floor on either side of the drawbar. The electrical connections between the locomotive and tender were made using connector sockets I ordered from Digi-Key Corporation.



Fred Miller wrote an excellent article about using these connectors that appeared in the NMRA Mid-East Region newsletter. They are inexpensive, easy to work with, and the perfect plug set for this application.

Module Mogul - 2

Adding sound to a model locomotive puts a premium on electrical contact.

Intermittent breaks in the current flowing from the rails to the locomotive are always aggravating, and a sound system only accentuates these lapses to the point that they can become infuriating. I followed Harold’s advice and added electrical pickups to the Mogul’s tender trucks, but I did not do it the same way he did.

I found electrical contacts to the tender trucks to be somewhat difficult. The tender balances on the center bolsters of the trucks as they swivel and rock along the track. Adding electrical wires running up from the truck wheels into the tender interferes with the balance of the tender and restricts the movement of the trucks.



I decided to add only one set of pickups to each truck. One truck would pick up power from the positive rail, and the other from the negative.



The electrical contact scheme I eventually settled on was to use Kadee phosphor bronze coupler centering springs as wipers making contact with the inside of opposite pairs of wheels in each truck.



Leads were soldered to the Kadee springs, threaded up through holes in the floor of the tender, and connected to the Tsunami sound decoder. A qualified success! This arrangement did provide power to the decoder, but there were frequent dropouts as I rolled the tender along the track. I hoped that these additional electrical pickups, along with the factory installed pickups on the locomotive wheels, would increase the reliability of operation.

After wiring the tender trucks, I purchased a Bachmann caboose that had electrical pickups to power an interior light. I intended to remove the pickup system from the caboose and use it to replace the Kadee contacts on my tender. When I looked at how the caboose pickups were done, they were so similar to what I had installed on the tender that I left my tender pickups as they were. If I had had the caboose trucks initially, I would have definitely modified their electrical pickup for installation on the tender trucks.

Module Mogul - 1

On30 owes much of its popularity to an O scale trainset released by Bachmann that runs on HO gauge track. The locomotive included in the set is a small 2-6-0, which has been the starting point for countless customizations, chop jobs, and kitbashes over the years.

I purchased a Bachmann 2-6-0 because it seemed perfectly suited for use on the
James River Division On30 modular layout. Perfect in appearance only, because in order to run the Mogul, it had to have DCC installed. And since the modules are often set up for public exhibition, it would be more interesting for the locomotive to have sound capabilities as well. The Bachmann 2-6-0 is currently not available with these options.

Harold Minkwitz posted a tutorial on installing sound in a Bachmann Mogul. I downloaded and printed his instructions, and followed them fairly closely.



After making sure the Mogul I purchased ran well, I disassembled the tender and removed the boiler.



I cut out the molded coal load, and drilled holes in the floor of the tender.



I trimmed a piece of basswood to size, cut two round holes in it, and silicon caulked the speakers to it and the assembly to the floor of the tender.



I wired the speakers, then temporarily connected them to the sound decoder. The power leads from the decoder were connected to a power pack to make sure everything was working up to this point.

Winwood Track Power

For expediencies sake, I decided to go with Micro Engineering turnouts in Winwood, rather than handlay. Micro Engineering has provided a location on the bottom of the frog to make a solder connection. This makes it possible to power the frog through a polarity reversing switch.

I soldered a wire to the bottom of the frog in each turnout, and fed the wires down through holes in the roadbed. All the wires were then connected to a Fast Tracks Frog Juicer board.



Down amidst all the bus wires and feeders is a small PC board that automatically and instantly corrects the polarity of a frog as soon as a locomotive wheel touches it. This board has eliminated the need for multiple sets of mechanical connections to double pole switches. The frogs are always powered, and their polarity is always correct.

Entering the Loop

Track construction on the P&EBR has extended up the mainline to the town of Ariel Church.




The turnout circled in red controls the entrance to the second reverse loop on the layout. A train coming up the mainline could take one route through this turnout and eventually return back to the turnout on the other route. The other end of the mainline also forms a loop. Running from loop to loop will allow trains to run continuously without ever coming to the end of the line. Controlling the entrance to the loop and the polarity of the electrical current in the rails requires some special circuitry and wiring.



A junction in the power buss provides power to a PSX-AR, which will immediately correct the polarity of the reverse loop power block whenever a locomotive enters it.



The PSX-AR is mounted on the benchwork under the Shops Yard. Power comes in from the junction in the power buss on the right, and the power buss for the reverse loop block goes out to the left.



The reverse loop power buss runs through the Piedmont Mill section of the layout. Pulling these wires was the first new construction on this section of the layout in years.



The reverse loop power buss runs through a barrier block under the middle of the Piedmont Mill section. The block is accessible from inside the bookcase that supports the section. The barrier block will provide junction points for the feeder wires in this section.

Once the buss wires had been pulled and the rails gapped for the reverse loop, I moved on to the automatic controls for the turnout at the entrance to the loop.



This is the turnout that forms the entrance to the loop and the Tortoise switch machine that powers it. The Tortoise is in turn controlled by the Hare stationary decoder attached to its electrical contacts.



The Hare is connected to the power buss and has an address that can be selected on a locomotive engineer's throttle. The engineer can then throw the turnout using buttons on his throttle. Throwing the turnout will cause the Hare to switch the polarity of the turnout frog to match the selected route.

The Hare also has the capability of throwing the turnout automatically if a train is approaching with the turnout set against it. In order for the Hare to sense which direction a train is approaching from, trigger rails have to be wired into the approaching tracks.



Trigger rails are short sections of rail wired directly to the Hare. When a locomotive runs onto a trigger rail, the Hare knows a train is approaching on that track, and will automatically throw the turnout if necessary. Having trigger rails controlling the turnouts at the entrances to both loops on the layout means "hands off" continuous running is possible.



The trigger rail wires are routed through this switch which will allow me to override the automatic turnout control function.

Trigger Rails

The track being laid in the Cove area of the layout completes a reverse loop.


The bright green turnout in the plan controls the entrance to the reverse loop.

The normal operation of the layout will not see trains going completely around the loop. The railroad will make a linear progression from Cove, past the Dust Mill, then past Meridian Quarry, and come to an end in the small transfer yard at Winwood. The track that closes the loop by running between the Transfer Warehouse and Winwood Mill will have the place where it passes through the wall hidden as much as possible.

While the loop feature will not be used most of the time, it will be very handy when I just want to watch the trains run. The other end of the mainline will also form a large reverse loop, so trains will be able to run continuously from loop to loop. But running electric trains in and out of reverse loops requires some power and track management. I am trying to automate these management tasks using electronic components from DCC Specialties.



The polarity of the track power in a reverse loop needs to be isolated and reversible in order for a locomotive to be able to pass through the loop without causing a short circuit. I am using a PSX-AR unit to manage the reverse loop track power. It can detect when a locomotive is entering the reverse loop power district, and correct the polarity of the track power so quickly that a locomotive doesn't even hesitate entering or leaving the loop.


The green turnout in the track diagram will determine which way a train will go when it enters the reverse loop. Eventually, the train will approach the green turnout from the other direction, which will require throwing the turnout in order for the train to continue out of the loop. I am using the "trigger rail" feature of DCC Specialties Hare stationary decoders to automatically line up the route for a train approaching the turnout at the entrance to the reverse loop.




Two short isolated sections of rail in the reverse loop have feeder wires soldered to them. The feeders send an occupancy signal back to the Hare when a train runs over the "trigger rail", letting the Hare know that a train is approaching the turnout, and from which direction.



The Hare will then automatically throw the turnout to line up the route for the train to exit the reverse loop.



I routed the feeders for the trigger rails through this "Frankensteinian" knife switch. The switch allows the trigger rails to be disconnected from the Hare decoder, and instead be powered directly by the power buss. This effectively turns off the automatic function of the reverse loop turnout, preventing the possibility of it being thrown inadvertently during "real" operation of the railroad.


Tripping Breakers

Laying out crossties was cut short by the arrival of reverser units from Tony's Train Exchange. The track power campaign could continue.


The PSX-AR controls a power block that includes the transfer yard. Eventually this track will form a loop allowing continuous running. The PSX-AR will automatically manage the polarity of the track so locomotives can cross into and out of the loop block without causing a short.

Without exception, every new set of power feeders off the DCC buss brought problems. The circuit protection in the Digitrax Command Station popped every time I tried to power up. At first, I would post messages and place calls to customer service in search of solutions to a wide range of mysterious problems. After a while it became clear that the common thread running through all my electrical issues was problems with my wiring, trackwork, or turnouts. Eventually, when the circuit breaker in the command station beeped, I stopped running to the phone and instead started working up a diagnostic routine for determining the cause of the problem. The aggravation of having the system go dead with me alone in the train room was nothing compared to what it will be like when a crew of operators is standing around looking at me and wondering why the trains won't run. A routine for quickly getting the layout up and running will be essential then.


I extended the LocoNet to a temporary UP installation at Glade Junction.

Once all the stationary decoders were powered, I could throw all the turnouts in unison, which was strangely gratifying, but hardly practical. Tony's provides elaborate instructions for programming the decoders, which includes setting CVs and assigning each decoder with a unique address.



The electrically isolated frogs in my Fast Tracks turnouts are about 2 inches long, so they must be powered in order to run small locomotives. Frog polarity is controlled by setting 10 dip switches on the stationary decoders to the proper sequence. Once these were all oriented correctly, the work train could really roll through Glade Junction unimpeded by electronic seizures and hiccups.



Time to build more track!

Along Glade Creek

Recent construction has seen a proliferation of wires under the roadbed at Glade Junction.

I am using Tortoise switch machines to throw my turnouts, and TTE Hare II stationary decoders to control the Tortoises. My reasons for using the Hare stationary decoders are to reduce the clutter on the fascia, and hopefully incline operating crews to bring their train to a complete stop, throw the turnout, roll through, stop, close the turnout behind their train, and continue. On such a small layout, delaying operations with some prototypical ceremony is essential for slowing everything down to extend run times.



The little work train runs back and forth finding dead spots and confused frog wiring.


Here the work train is delivering new crossties to the railhead. Soon the line will be extended up Glade Creek to Dust Mill Yard.


Laying out ties for the first turnout in Dust Mill Yard. This is the only turnout on the layout I plan to build in place. All others will be built at the bench using Fast Tracks fixtures.

First power to rails

I built a small shelf under the narrowest point in the benchwork for my Digitrax DCS 100 and power supplies.



From here I strung a power bus and the LocoNet cable to the new Transfer Yard.



Track power and trains running in the Transfer Yard!