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Unofficial T-Trak Handbook



Unitrack is very reliable, and doesn't usually cause problems. A standard module only has 1 interior rail joint per track. If a module has a lot of short pieces of track the number of rail joints increases quickly-- and those are the places where reliability (and your trains) can falter.

To increase reliability I recommend soldering all track connections on modules. Now, you can argue that soldering makes it difficult to un-build a module. Practically speaking, what are the chances you'll ever do that? If you ever do, you'll probably be able to pop off the entire length of track at once and reuse it-- soldered joints and all.

I've been going back and soldering the track on my existing modules with mixed success-- fresh, un-sceniced track solders very nicely. Unfortunately, once you've got grass, glue, glop, and goop in the gaps, it's almost impossible to solder. For those places I recommend drilling holes through to the underside of the module, soldering wires to each section of track, and joining them beneath the layout. I'm hoping for much better performance this year! (:

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Track Power Connections

Blue Wires to the Outside

Kato's Unitrack comes complete with at least 3 ways of connecting power to the rails:

(1) The 20-041 (62mm) Feeder Track

On the Official T-Trak Web Site (T-Trak Logo) the diagram of the basic module shows the feeder tracks mounted at opposite ends of the module, with 3/4" holes to allow for the power feeds.

When assembled in this manner, the blue wires on the Feeder Tracks will power the outside rails.

So the rule is: "Blue wire to the outside"

(2) The 24-818 Terminal Unijoiner

When using the Terminal Unijoiners make sure the joiners with the blue wires connect to the outside rails.

(3) The 24-828 Double-Track Viaduct Power Cord

Unfortunately, the design of the Viaduct power attachments is contrary to the T-Trak "Blue to the Outside" rule. However, there's a fairly simple work-around.

Here's a view of the top and bottom with parts identified...

Viaduct Power Connections Overview

Here's a close up of the Viaduct power connections.

The viaduct connectors are keyed; there's a notch along one side of the socket, and a corresponding nub on the plug. This makes it impossible to mis-align the plug, but doesn't allow Blue-to-the-Outside.

The fix is simple. I've placed the power connections on the 2 adjoining sections of Viaduct so the connections are on the ends of the Viaducts nearest each other.

This places the key notches towards each other, and also reverses the connection. Power each track using the connection points on different sections of Viaduct, and you still have Blue-to-the-Outside.

You can only do this if the Viaduct includes at least 1 straight section, or if your Viaduct includes an "S" curve.

Of course, this all assumes that you're going to feed power to the viaduct using the Viaduct Power Connectors. If you do, you'll have to come up with a way to hide the power cord. It may be easier to power from the ends of the viaduct and avoid this problem entirely!

Viaduct Power Connections Blue Fix

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Power Feeds

Kato's Unitrack is an amazingly robust product. It's almost impossible to mis-align a rail joiner, and the action of joining and unjoining track keeps the contacts clean.

Unfortunately, the rail joints within a module never have a chance to be cleaned in this manner. And all of the scenic paint, glue, gunk, and goo are magically drawn into the narrow confines of the Unijoiners.

In many cases this is not a major problem; there is still enough contact to keep power flowing. However, as T-Trak layouts grow larger and larger all of the minor power drops add up. And the trains s-l-o-w d-o-w-n on the sections of the layout farthest from the power connection.

With analog/DC controls this is bad enough, but with digital/DCC it's even worse.

The solution is to use the power connections that should be available on many modules and provide a parallel path for power-- plug in more modules! This is why it's important that all power connections follow the "Blue-to-the-Outside" rule!

If there are no power connections in a convenient location, 24-818 Terminal Unijoiners can be used between any 2 modules. It is probably a good idea to split the cord, so you have a lot more slack between the 2 joiners-- when you separate the modules, one joiner is going to stay with each module!

Center-Of-Table Power Trunks

If your layout has grown to an amazing size you may notice that your trains slow down at the end farthest from the power connection. The solution is to plug more modules into track power. But it's a pain to have to hook together a large number of Kato Extension Cords (about 3 foot long each) in order to feed power to the "other end" of the layout.

With each cord you get an additional plug/jack connection. And the cord is fairly small gauge, so you will lose some power with each section you add.

A more robust (and longer) extension cord would be nice.

Some things to consider:

What I'm doing:

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Power to the Track!

The 'greatest' improvement in model railroading in the past few decades has been the introduction of DCC, Digital Command Control. Unfortunately, I have a fleet of old-style DC/Analog-equipped locomotives.

As such, I run both DC/Analog and DCC/Digital equipment on my T-Trak layout. And need to switch track power from one source to the other.

I've equipped my power unit with toggle switches to make this process easier.

my "Power Routing Switcher"

Track Power Routing Switcher

Because T-Trak is wired with the "Blue Wires to the Outside," adding a crossover to the layout will result in a short-circuit the instant the turnouts are moved to the 'crossover' position.

The "Phaser" toggle switch was added to reverse the power to one of the tracks. It is simply a standard reversing switch. It reverses the polarity of one track so a double crossover can be used.

All the pieces are available at your local Radio Snack store.

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Power to the uh, Turnouts!

Ted wrote: "One part of the Unitrack system I don't care for is the turnout control switch... What kind [of toggle switch] do I need and how do I attach the wires from the DC converter and the turnout? Thanks in advance, Ted"

The Turnout and Motor

The Kato Turnout is moved by a Turnout Motor. It's a tiny solenoid, hidden under and inside the ballast strip. The Turnout Motor runs on DC (Direct Current). This is different than the common Atlas turnout motor, which will run on DC or AC (Alternating Current).

Because the Turnout Motor runs on DC, it only needs 2 wires connected to it. To throw the turnout, one wire ('A') is positive and the other ('B') is negative; going in the other direction 'A' is negative and 'B' is positive.

The Turnout Motor is only fed electricity for the moment it takes to move the points.

Controlling the Turnout

The Kato turnouts can be controlled manually or electrically. There is a manual lever poking out of the ballast strip next to the free end of the point rails. There are 2 ways to electrify the Kato switches:

(a) The Official way

Use the official Kato #24-840 Turnout Controllers, and the #24-842 DC Converter (ie Power Adapter).

The DC Converter (Power Adapter) is a rectifier. Physically, it is a little box with wires on one edge, and 2 snap connectors (very much like the ones on a 9v battery) on one side. The wires connect to the AC terminals of your power pack, and DC is fed out of the snap connectors.

The Turnout Controllers are blue plastic electrical switches. Snap connectors on both sides (male on one, female on the other) allow a row of controllers to be snapped together. The DC Converter is snapped to the left side of the first controller in a row to supply electricity to the entire row. A socket on the back mates with the plug on the cord from the turnout motor.

The Turnout Controller is a momentary contact Double Pole, Double Throw (DPDT) switch. As you move the control from one position to the other, contact is made for a brief fraction of a second, sending DC current to the Turnout Motor.

(b) The Other way

You can use MOMENTARY CONTACT double-pole, double-throw switches (with MomentaryOn / Off / MomentaryOn positions). They are wired the same way a reversing switch for track power is wired, but the power coming in is fixed DC (Direct Current) from your power pack, and the power goes out to the Kato turnout connector. You'll have to cannibalize a Kato power cord to get the connector (I haven't had any luck finding naked Kato connectors). This lets you pick a MOMENTARY CONTACT DPDT switch that you can mount on your control panel.

NOTICE: IF you use the Unofficial Way, YOU MUST use a MOMENTARY toggle switch! If you use a plain, ordinary toggle switch, you'll burn out the turnout motor!!! And have just a manual turnout.

DPDT Wiring Diagram

If you look at the back of the momentary double-pole, double-throw, center-off toggle switch, it has 6 electrical terminals: 3 pairs of 2 terminals. Hold the momentary toggle switch so there are 3 rows of 2 terminals. It is wired the same as you would wire a reversing toggle switch for track feed. Connect the center 2 contacts to the auxiliary DC (Direct Current) terminals of your power pack.

The remaining four contacts are wired as follows: Connect 2 short wires across the 'diagonals' of the momentary toggle switch: from upper-left to lower-right, and from upper-right to lower-left. Wires to the turnout motor connect to the upper-left and upper-right contacts.

Since a switch doesn't care about polarity, it doesn't matter which pair of wires goes to the track, and which pair goes to the DC Power supply.

This re-creates the effect of the Kato controller. When you push the momentary toggle in one direction, wire 'A' is positive and 'B' is negative; pushing the momentary toggle in the other direction, 'A' is negative and 'B' is positive. When you mount the momentary toggle switch in your control panel, you can turn it around so the toggle moves in a logical direction.

Concerning the wires heading for the turnout: you'll probably need to sacrifice a Kato extension cord to get the female connector that mates with the connector that powers the turnout motor. If you're -really- brave, you can sacrifice the connector on the turnout and just connect the wires. (: However, I've found that being able to unplug things has a certain amount of convenience.

The problem with using a momentary toggle switch is that you can't tell which direction the turnout is in after it's thrown-- the position of the toggle switch is always in the center. IF YOU INSERT A MOMENTARY PUSH BUTTON (ie doorbell button) IN ONE OF THE LEADS FROM THE POWERPACK, you can use a normal (non-momentary) DPDT toggle switch. And the position of the handle will point in the direction the turnout is thrown. You will move the toggle switch to the desired position, then push the momentary push button.

The drawback with this is that you have to throw the toggle then press the button. But the toggle does represent the position of the turnout. IF YOU DON'T USE THE MOMENTARY PUSHBUTTON IN SERIES YOU'LL BURN OUT THE KATO TURNOUT MOTOR!! You could make the toggle switch a 3PDT (Three-pole, Double-throw) switch, and use the additional contacts to control the panel lights.

One possible advantage of the switch/pushbutton combination is that you could wire it so the one button controls a whole bank of switches: flip a dozen or more toggles, press one button, and watch the layout walk across the floor as all of the turnout points thud against the stock rails at the same time. Your power supply may not be up to it though... (:


You've been warned!

(c) The -Other- Other way

Did I hear someone say "pushbuttons?" Here's a circuit that will let you use momentary SPST (Single-Pole, Single-Throw) pushbuttons to control your turnouts. The power source is the -AC- output from a power pack, and a couple of 2.5 Amp, 1000 PIV (Peak Inverse Volts) diodes to turn the AC into pulsed DC to run the turnouts. You'll have to experiment to figure out which button moves the turnout which direction.

Kato Turnout Control Using Pushbuttons

This diagram shows how the diodes turn AC into pulsed DC. AC current is a "sine wave;" that's the shape of the curve (and my curve is only an approximation of the correct shape). Notice that AC current starts at zero, goes positive to a peak, then back thru zero and negative by the same amount, then back to zero. The diodes select either the positive or the negative current, depending on which button is pressed, and route it to the turnout.

AC Current Diagram

(d) Odds 'n' Ends

There are several circuit ideas out on the web that will light up appropriate indicators while allowing you to use a momentary DPDT switch. Start with

Someone asked if it was necessary to have a power supply for every 6 turnouts. No, you should be able to plug a large number of Kato controllers together (or wire an equally large number using momentary switches) without problems, as long as you only throw one or two turnouts at once! The problem is when you try to throw all of the turnouts at once-- the power supply won't be able to handle the drain.

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(mine had number 20-500 molded on the side)

Kato Turnout Controller Exterior Right Side Kato Turnout Controller Exterior Left Side

Exterior Right Side                         Exterior Left Side

This is the Kato turnout controller. Due to persistent curiosity, I opened up one of these to see what was inside. No, there's no conventional switch in there!

The controller is clamped together by the male and female snaps on the outside and 2 metal posts inside the shell. The female snap is swaged to the post. The post slips into the right half-shell, and the snap fits into a socket; it won't slip through the shell. A clip on each post keeps it from falling back out and keeps it standing straight during assembly. After the left half-shell is placed over the controller, 2 teensy screws hold the male snaps to the posts, and clamp the controller together.

Kato Turnout Controller How To Open

Left Side with snaps unscrewed

Back inside, the female plug (the one that mates with the cable that heads to the turnout motor) fits into molded guides at the back of the controller. 2 springy wires connect to the plug, and describe a U-shaped path, with one wire on the 'North' side of the 2 posts, and the other on the 'South' side.

Kato Turnout Controller Interior Left Side Kato Turnout Controller Interior Right Side With All Parts

      Left Side                      Right Side with all parts in place
                                   Control handle connects to The Thingy

A complicated-looking pivoting Thingy between the posts grips the wires. The control handle is a separate piece, and wiggles the Thingy either clockwise or counter-clockwise. As the Thingy moves, one wire is pushed against post "A" while the other is pushed against post "B." In one direction wire 1 touches post A, and 2 touches B, in the other direction wire 2 touches post A and 1 touches B.

Kato Turnout Controller Interior Right- handle and cylinder removed Kato Turnout Controller Control Handle

   Right Side, Handle Removed                               Control Handle

Kato Turnout Controller Interior Right- thingy removed Kato Turnout Controller The Thingy and Cylinder Kato Turnout Controller The Thingy and Cylinder

Right Side, Thingy Removed                       The Thingy and Cylinder, 2 Views

A tiny cylinder slips over a post on the Thingy to reduce friction between the Thingy and the control handle.

A simple yet elegant way to build a switch! And the person who designed the "Thingy" is amazing!


(mine had number 20-504 molded on the side)

This is a lot simpler-- Inside the case is small circuit board with 4 diodes mounted on it-- a standard bridge rectifier circuit. The circuit fits into the base of the case. The lid fits over the circuit board, and 2 female snaps fit through the lid. Two teensy screws clamp the snaps to the circuit board and the back of the case, and also hold the lid shut. The case indicates 17 volts AC in (via wires), and 12 volts DC out (via the snaps).

Because it's a bridge rectifier, you can feed it with DC if you like, and the correct polarity power will show up at the snaps.

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How a DPDT Reversing Switch Works

An electrical switch can be either Continuous contact or Momentary contact. Examples: Continuous-- a light switch, one position is ON, the other is OFF. Momentary-- a doorbuzzer button, the buzzer only buzzes when your finger is pushing the button.

A simple on-off switch is a Single-Pole, Single-Throw (SPST) switch. Power comes in on a single wire, and can leave by another. The switch provides a mechanism that allows you to join the 2 wires with a piece of metal, completing the circuit.

A Double-Pole, Double-Throw (DPDT) switch consists of 2 switches (Double-Pole), each of which can complete 2 circuits (Double-Throw). The 2 switches (Poles) are mechanically joined internally (by an insulated 'device') and can not be operated independently. Within each pole, power comes in on a single wire (the Common wire), and can leave by 2 different routes. The switch provides a mechanism that allows you to connect the Common wire to either of the other 2 wires.

Double-throw switches come in several flavors: 2 "ON" positions; 2 "ON" positions and a center "OFF" position; and Momentary "ON" / "OFF" / Momentary "ON." This third type is what we need to control Kato Unitrack turnout motors.

DPDT Wiring Diagram

The diagrams show the switch in its 2 "ON" positions. Power arrives via the wires connected to the center (Common) pair of terminals.

Depending on the position of the switch, internal connections link power to the top terminals, leading to the turnout motor, or to the bottom terminals.

If power is connected to the bottom terminals, it flows acros the "X" wires to the top terminal on the -opposite- side, reversing the polarity of the power (ie the Red and Blue are reversed).

It doesn't matter if you swap the 2 pair of wires leading to the switch; it functions just the same if the wires connected to the common terminals go to the turnout motor and the top terminals are connected to the power pack.

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T-Trak Power Box

Old Power Monster

Once upon a time I built a Power Control Center to make it easier to set up my T-Trak layout. My goal was to avoid having to re-connect wires to power packs, Zephyr, whistles, horns, and other items. I had toggle switches to select between DC/Analog and DCC/Digital power for each of the 2 T-Trak mainlines, and 'phasers' (reversing switches) for each power source for each track. There was a programming track with an on/off switch, and buttons to sound the horn or whistle.

Track power cords were permanently attached to the right spots, and there were other spots to conveniently plug in various cords for horns and whistles.

The Power Control Center was built in a Stanley home tool center. Originally, it had 3 sections, but at the store they had a stray 'middle' section, and I bought that, too. Plastic latches locked the sections together; they were interchangeable.

It was usable, but had several flaws.

-- It was heavy. Fortunately, it had wheels and a dolly handle.

-- The lid had to stay closed if you wanted to use the programming track!

-- Stanley did a decent job of designing the unit, but th