This page is intended to explain a little about the DCS control system and what you can do with the remote handset(s) and Track Interface Unit(s).

Firstly it may be as well to explain what you can expect if you already have an electric power-supply/controller

All MTH gauge 1 locomotives can accept a conventional AC , constant voltage DC or rectified DC supply. To obtain a reasonable maximum speed and power the supply should be capable of a minimum of 5 amps at 18 volts. It should not exceed 22v, 20v is a "happy" high power value. If you like multiple unit lash-ups, double heading or whatever you might want to consider a 10A supply. On a conventional resistive or variable voltage supply you can get forwards and reverse motion, lights basic sound including start-up, running and shut-down sequences along with smoke output. The upper volume of smoke and sound can be limited by potentiometers on the locomotives. Those with an AC output controller may be able to send coded power pulses to reverse the locomotive, sound the horn or bell or loosen the couplers. If your power supply generates a high frequency "chopped" output then the power pulses may be interpreted as illogical DCS commands and for this reason "chopper" controllers are simply not recommended.

So what can the TIU-handset combination do? Let us consider the general specification of the TIU:

The TIU has four power inputs and four power outputs. Two of the input/output units can only be used to control DCS equipped locomotives. These outputs are effectively fixed voltage with command signals being sent down one of the rails. Just for your information the right hand side of the locomotive is the one that picks up the signal so if the locomotive does not seem to respond try swapping the power leads over (this will also need to be attended to if you have a reversing loop).

The other two outputs can be used as either independent "fixed output" DCS control mode or for conventional (variable voltage control). The features that are available depend on whether the the motor in the locomotive needs an ac or dc supply. If it needs an ac supply then the TIU inputs can be fed from a fixed output transformer and the TIU can be controlled from the handset to give speed/power control over the locomotive. If the locomotive needs a dc supply then the TIU can "pass through" a variable voltage but will not act as the voltage controller itself. One option for dc control is to use a bridge rectifier on an ac output. The bridge rectifier will need to be rated for the current load and will entail a voltage drop but will allow the use of simple fixed output power supplies to power the TIU.

Each output controls a "loop" or section of track. These track sections must be electrically isolated from each other and common-return wiring is not an option. Under DCS control more than one locomotive can operate on each track section, either as a diesel lash-up, double heading, push-pull helper or independent trains as long as the total power drain of 10 amps per output is not exceeded. If you had four track sections and your locomotives cruised at an average of 3 amps then one TIU could deal with 12 seperate running locomotives and any number of others parked up. Obviously the TIU cannot provide more output power than it is supplied with and each of the outputs in use will need an adequate supply on the input side. If you tend to operate only one locomotive per output then a 5 amp supply will most likely suffice for most purposes with 10 amp capability recommended if you want maximum flexibility.18 volts should be adequate, and will lead to longer service life on items like the locomotive and coach lighting, but if you really want to test for maximum drawbar pull then 20 or 22 volts will give roughly 10% and 20% more effort. MTH recommend that a 15 amp quick-blow fuse is used on each of the TIU inputs, to protect against the possibility of damage if there is a short on the track, and it is perhaps worth repeating that 22volts is the maximum voltage allowed on the supply. The TIU can be connected to a chain of Accessory Interface Units and also to a computer to allow new sound files to be loaded into locomotives. It should be noted that there are no manual controls on the TIU itself, it can only be controlled by the remote handset.

The handset is powered by AAA batteries and has a free uninterupted range of around 50 feet. Remember that the range is not from the handset to the locomotive but from the handset to the TIU. The handset has a two-line lcd display, a central thumbwheel and an array of pushbuttons that give immediate control over the bell, whistle/horn and coupler without you having to remember the code sequence for that particular feature. MTH locomotives that are on controlled sections of track are first detected and then logged on to the handset's memory. The selected locomotives can then be controlled for speed, direction, sound and smoke volume, all the bells and whistles and other sundry sound effects that the locomotive has been programmed with plus the uncoupler for those recent locomotives that have this feature. The handset can be set to one of five frequencies should you want to operate layouts in close proximity at an exhibition, or if you want to control more than four track sections with further TIUs, but in the latter case I would recommend allocating a handset to each TIU to save confusion if the wrong frequency is selected (and particularly if you should ever need the "emergency stop" whilst on a different frequency). It is also possible to have two operators, each with a handset, controlling through the same TIU. In this instance, if there is a conflict in operator intentions, the locomotive(s) will obey the most recent valid instructions.

The TIU and handset tot up to more than two hundred pounds and as such may not be considered a bargain in the first instance. I would however suggest that you look at the pricing of just one conventional transformer-controller that can actually manage a 10 amp output and you may find that you are looking a a three to four hundred pound price tag. If you then consider that the TIU needs just a basic 18v supply, that it can control four separate outputs and gives you full access to all the DCS control features then it seems a good deal in comparison.