DAWSON CREEK SUBDIVISION

RAILWAY PROTOTYPE MODELLING IN N SCALE

Timothy J. Horton

TURNOUT CONTROL

I decided to use miniature servos for powering and controlling my turnouts. My benchwork has a fairly thin profile and the servos would not be seen below the fascia, whereas the more traditional machines would.

The servos require a power supply of 12 volts so it was necessary to run an auxiliary power bus around the layout for turnout control. I ssembled an auxiliary power panel comprising a power bar, three 12 volt power supplies, three DCC booster boards and a barrier strip for connection to the layout.

This photograph shows a test with power into the DCC booster board, a connection to the Singlet Servo decoder, and a further connection to the servo at left.

I have also connected a miniature toggle switch to the Singlet servo decoder as I wish to control the turnouts from the fascia with the toggles. The booster boards, Singlet servo decoders and servos were sourced from Tam Valley Depot.

There are eight turnouts on the mainline including Septimus, Sundance and Tremblay.

This photograph shows the eight Singlet servo decoders which were assembled from kits. The kits are an effective way to keep the unit price down and require only basic soldering skills to attach the push buttons and bi-colour LEDs. I mounted the buttons and LEDs on the same side so that the Singlets could be attached to brackets under the layout.

The miniature toggle switches were sourced from a local electronics store. Lead wires were attached to them for the runs from the Singlet servos to the fascia control panels.

I encountered some issues with these miniature toggles which may have resulted from the soldering process. The use of heat sinks during soldering seemed to eliminate the damage to the toggles from the soldering process.

After years of operating on other people's layouts, I wanted a system of turnout control which was simple and intuitive. I opted for small panels directly in line with the turnouts which would accommodate the toggles, and larger schematic panels for the middle of the sidings. All of the panels were rendered in Adobe Illustrator and then produced on lamicoid.

Pictured at left is the auxiliary power panel in place underneath the layout. I chose a location underneath Chetwynd Yard as the majority of turnouts will be in the two yards situated above. It is also located near an available wall outlet.

I decided to create three separate bus runs for the turnouts: one for the turnouts in Chetwynd yard, one for the mainline turnouts, and one for the turnouts in Dawson Creek yard.

This photograph shows the complete installation in place for the west switch at Tremblay. The servo is located on a bracket directly below the turnout. The frog juicer is attached to the other side of the bracket and connects to the track bus wires and the frog. The servo is connected to the Singlet servo decoder which is mounted to the right on a separate bracket. The Singlet servo decoder is connected to the auxiliary bus run which supplies the 12 volt power. We can also see the control panel on the fascia with the toggle switch.

Here we see the fascia control panel for the west switch at Sundance, with the panel for the south switches at Septimus to the right. The panels are located directly in front of the turnouts, and they identify the main track and sidings.

I have noticed on other people's layouts that operators frequently have to step back or bend down to read the lower deck panels. I decided to mount the lower deck panels on angled blocks for ease of viewing.

The centre panels are schematics for the entire location and are patterned on the railway's actual Condensed Track Profiles. They identify tracks and industries, and indicate direction of travel with an arrow (ie. south and north, or west and east).

The panel for Septimus is on the left, and the panel for Sundance is on the right. These are also mounted on angled blocks attached to the fascia. This arrangement has proven to be very successful.

This photograph shows the control panel for the east switch at Sundance on the left, and the control panel for the north switches at Septimus on the right.

Note that both panels are located directly in line with their associated turnouts.

The panels with toggle switches are screwed to the angled blocks and the lead wires for the toggle switches pass through a hole in the angled block and fascia.

This is the centre schematic panel for Tremblay on the upper deck. All of the panels for the upper deck are attached directly to the fascia as the typical viewing angle does not require them to be angled.

In addition to indicating track names and direction of travel, the panels identify industries. The schematic panel at Tremblay identifies the Alberta Wheat Pool elevator which was located there.

Here we see the control panel for the west switch at Tremblay which is also mounted on the upper deck fascia. There were wires yet to be attached at the time this photograph was taken.

This photograph shows how the entire servo installation is low enough in profile so as to be concealed by hte fascia, which extends only two inches below the underside of the benchwork.

This view shows the underneath of the upper deck for Dawson Creek in the vicinity of the east ladder tracks, where there is a large concentration of turnouts.

For each turnout there is a servo mounted on a bracket with a frog juicer attached to the rear of the bracket. A second bracket accommodates the Singlet servo driver.

The frog juicers are connected to the track bus for power, and the Singlets are connected to the auxiliary power bus located toward the rear of the benchwork.

For Dawson Creek Yard there is a central schematic panel which identifies the tracks and locates the various industries. The schematic is based on the one for Dawson Creek in the railway's Condensed Track Profiles. This panel is tilted 30 degrees for optimum viewing by a standing operator.

Turnouts which are located by themselves are controlled by a small panel mounted directly on the fascia. The toggle is directly in line with the turnout.


In this photograph we can see the turnout control panel for the East Ladder, which contains the toggle switches for a large concentration of turnouts at the east end of the yard. A similar panel controls the West Ladder. The ladder panels are tilted 30 degrees.

On either side of the East Ladder panel are smaller panels for individual isolated turnouts. The one on the left is for the BC Hydro spur, and the one on the right is for the Elevator Track. A total of eight panels serves the yard at Dawson Creek.

This view from the west end of Dawson Creek Yard illustrates the tilted panels. Nearest the camera is the turnout control panel for the West Ladder, then the individual panel for the Peace River Lime spur, the central schematic panel, and the East Ladder panel.

This view shows how the angled control panel mounts are intended to improve the viewing angle for operators when standing in front of Dawson Creek yard. The panels for hte upper deck are angled at 30 degrees.

The servos used to control my turnouts are purchased from Tam Valley Depot and are sold as "Micro Switch machine w/o Snap Switch". They come ready to install with mounting bracket and throw wire.

Above the packaging you can see several servos installed with the throw wires protruding up through the turnouts and waiting to be trimmed. The servos mount underneath with adhesive tape and screws.

This photograph shows a Micro Switch machine out of the packaging and ready for installation. Note the double-sided tape attached to the top of the bracket. This is used to attach the bracket initially, and then holes are drilled for the mounting screws which secure the bracket in place permanently.

I bend the portion of the wire above the bracket back a little in order to reduce tension on the throw bar. This has reduced damage to throw bars from excessive pressure exerted by hte throw wires.

After securing the servos in place underneath, the throw wires must be trimmed to clear the trains. There is insufficient clearance between the rails to cut the throw wires with nippers, so a Dremel tool with cutoff disk is used. This generates a fair amount of heat which can cause the throw wire to cut right through the throw bar, so a heat sink is used to draw heat up the wire and away from the throw bar.

Here we see my friend Michael Batten cutting a throw wire with the Dremel tool and cutoff disk. Painters tape is used to avoid damaging the rails and ties.

After cutting the throw wire, it is checked for clearance by running a locomotive through the turnout. If the wire is still too high, the final adjustments are made with a file. A Micro-Trains trip pin gauge is used to ensure that the top of the throw wire is below the rails.

In this photograph Michael is filing down a throw wire which has been cut. The green tape protects the ties from damage. This step generates a fair amount of metal filings which must be vacuumed up before a locomotive is run through the turnout again. The rails are also cleaned to remove any tape residue.

Our tunrouts require a way to reverse the polarity when trains travel back and forth through them. I use the frog juicers from Tam Valley Depot, which are mounted on a small board. I attach these to the back of the servo bracket with double-sided tape,

The frog juicers are connected to the track bus with two wires, and to the frog with a third wire. The frog juicers are powered from the track bus and operate automatically.

This view underneath Chetwynd Yard illustrates the servo and frog juicer for the turnout serving the Imperial Oil spur after installation.

The black and red wires going into the frog juicer are from the track bus. The green wire is from the frog.

Compared with other turnout machines, the small footprint of the servos is evident in this photograph. This is an important consideration when building a small shelf type layout with shallow fascia.

The servos require some method of control. Tam Valley Depot offers the Singlet decoders which include a pair of push buttons and a pair of indicator LEDs. The Singlets have a plug to receive the cable from the servos.

The Singlets can be purchased assembled with the buttons and LEDs on the rear side for mounting in the fascia. I wanted to mount the Singlets underneath the layout and opted instead to purchase them in kit form, which also offers a cost savings.

This photograph depicts the Singlet decoder in kit form. As mentioned, the assembled Singlets come with the buttons and LEDs mounted on the rear of the board.

I elected to mount the buttons and LEDs on the front of the board thus leaving the rear surface flat, so that I could mount the decoder on a bracket underneath the layout.

The leads for the buttons and LEDs are inserted through holes in the board and soldered into place.

Here is a Singlet assembled from kit form with the buttons and LEDs soldered in place on the front of the board. The buttons activate the servo back and forth and the bi-colour LEDs indicate the direction thrown.

I have attached female header sockets next to the blue power terminals. These will receive male headers attached to the leads for the toggle switches out on the fascia control panels. The toggles will override the push buttons and allow operators to activate the servos from the control panels on the fascia.


In this photograph we see two Singlet decoders in place underneath Chetwynd Yard. They are mounted on the same brackets as the servos.

A triple wire cable extends from the servo to the Singlet and connects via a modular plug.

The Singlets are powered by a pair of feeder wires extending from the auxiliary power bus wires at the rear of the benchwork. The auxiliary bus wires are powered by standard 12 volt power supplies.

Underneath Chetwynd Yard I attempted to arrange all of the Singlets so that they faced out towards the fascia, so that if necessary I can look underneath the layout and monitor their performance. Their placement is limited only by the length of the cables to the servos.

This photograph illustrates eight Singlets in place underneath a portion of Chetwynd Yard. The relatively small footprint of the servos and Singlets is very helpful when powering a large number of turnouts in a small space, such as a yard ladder.

The control panels for Chetwynd Yard include a large central schematic which identifies tracks, industries and facilities, and smaller panels to accommodate the toggle switches for throwing the various turnouts. These panels include the south and north ladders, the mechanical shop area, the Canfor mill, and the Imperial Oil spur.

The panels are rendered in Adobe Illustrator and produced on black textured lamicoid.

Here are the toggle switches ready for insertion into the control panels for Chetwynd Yard. The 28 AWG stranded lead wires are soldered to the tabs on the miniature toggles and the connections are then covered with heat shrink tubing.

Based on prior experience, heat sinks were used during the soldering process to prevent damage to the switches. They were tested with a multi-meter after soldering to verify correct operation.