Model Railway Glossary

• ANALOGUE CONTROL:  Conventional track voltage control system, typically varying between 0 and 12 volts DC for speed control and polarity reversal for direction control.

• COMMON RETURN:  A conductor which is common to more than one part of an electrical circuit and which forms the return path for the current from these parts of the circuit.  Normally one rail of all sections or circuits of a layout is chosen as the common rail and current from all these sections or circuits returns to the power supply through this rail.  The other rail can then be divided into sections or circuits as required.

• CUTOUT:  A protective device built into an electrical circuit for the purpose of switching off the current when the load reaches a predetermined number of amps.  All Gaugemaster controllers and cased transformers are fitted with these devices on all outputs.  They reset automatically when the cause of the overload is removed.

• D.C. CURRENT:  D.C. current flows constantly in the same direction along its conductors which are termed positive and negative.  The polarity of the conductors can be reversed and the current flows in the opposite direction.  All controlled outputs from Gaugemaster controllers produce D.C. current which has been converted by the controller from A.C. current delivered by the transformer.

• FEEDBACK:  Feedback controllers create a closed loop between the controller and the locomotive which senses the load in the circuit and constantly adjusts the output.  This will maintain the locomotive at an even speed up and down gradients and around curves without altering the regulator of the controller.  Feedback controllers are not suitable for Portescap or other coreless motors or for poor quality mechanisms particularly in ‘N’ and other small gauges.

• INERTIA:  See Simulator

• MOMENTUM:  See Simulator

• POLARITY:  The two directions of current flow, positive (+) and negative (-), or potential in an electrical circuit.

• PRIMARY WINDING:  This is the winding of a transformer which is connected to the source of supply, normally the mains.

• REVERSE LOOP:  A reverse loop is created where a track leaves a circuit and then rejoins it with the train going in the opposite direction.  This will result in a short circuit unless the section is isolated from the rest of the circuit.  A DPDT switch is then used to reverse the polarity of the circuit concerned.

• SECONDARY WINDING:  This is the output winding of a transformer and is usually isolated from primary winding.  Many transformers have two secondary windings.

• SIMULATOR:  This is sometimes called "inertia" or "momentum".  It allows controllers so fitted to automatically accelerate a train, allow it to coast or be braked to a standstill.  This is achieved by two controls, a regulator and a brake and gives more realistic acceleration and braking.  In Gaugemaster controllers it can be switched off to allow the controller to be operated with standard control.

• TRACK ISOLATION:  Track isolation is particularly important with modern controllers.  You should always ensure it is not possible for more than one controlled output to be connected to the same circuit or section at the same time.  You should similarly ensure that A.C. and uncontrolled outputs are not connected to a controlled circuit.

• TRANSFORMER:  A device designed to change the voltage of an A.C. supply.  All transformers deliver A.C. current and this is converted to D.C. by the rectifier circuit in a Gaugemaster controller (see also primary and secondary winding).  Transformers are often used to power accessories on a layout (e.g. Point Motors).

• VOLT:  This is the standard unit of electrical pressure, and indicates the potential difference between conductors in a circuit, it can be either A.C. or D.C.

• DIGITAL:  A train command system, fast gaining ground on older Analogue systems in terms of popularity.  Whereas analogue systems work by providing a regulated supply of power to the track that increases or decreases according to user input, Digital systems supply a constant power supply to the entire layout.  Trains are operated through a command signal, sent through the track to the locomotive.  With each locomotive operating on it's own frequency, locomotives can be commanded individually.  See the article Introducing the World of Digital for a more detailed description.

• ACCESSORY DECODER OR MODULE  Used to control any accessories on a layout, such as signals, lighting, points and so on.

• ADDRESS:  A number identifying each individual locomotive and accessory decoder on a layout.  When a controller is set to a particular address, only the decoder set to the corresponding address can read the instructions from the controller.

• BOOSTER:  Used to supply power to the track, and to increase the rating on an existing supply.  One or more can be used alongside the Command Station.

• COMMAND STATION:  The central hub, or brain of the Digital system, this unit is where control data is converted into electronic format before being sent to the track.  Only one command station should be used per layout.

• CONSISTING:  See Double Heading

• CV:  Configuration Variable.  Components within a decoder which store the characteristics of that device.  Each component has it's own reference number, and these can be individually programmed.

• DCC:  Digital Command Control.  A control system for Digital model railways that is now the most widespread system worldwide.  The standard set down by the NMRA (National Model Railroad Association) in the USA allows equipment from different manufacturers to be used together.  The Gaugemaster Prodigy Advance System uses the DCC command language.

• DECODER:  Circuit board used for operating Digital models.  Any locomotive or accessory to be used on a digital system requires a decoder, which receives and interprets the Digital information sent by the Controller.  Many decoders offer added functions such as lighting, sound and so on.  These are referred to as multi-function decoders.

• DOUBLE HEADING:  Often known as consisting or multi-traction, a means whereby two or more locomotives can be run together under the same address.

• MAIN TRACK:  Any track or section of track that is part of the normal railway layout - as opposed to Programming Track

• MULTI-TRACTION:  See Double Heading

• NMRA CONFORMANCE:  Products that have passed the NMRA's testing procedures are eligible for a Conformance Warrant if the manufacturer also agrees to fix any discrepancies that might become apparent in the future.  The Conformance Seal is awarded by the NMRA for products passing the Conformance and Inspection program for particular NMRA standards.

• NMRA STANDARD:  A code of practive developed by the National Model Railroad Association in order to acheive standardised decoder formats.

• PROGRAMMING:  The action of setting the internal parameters of decoders and other control equipment.  During programming, values are set for CV's to determine the characteristics of locomotives, decoders and other programmable Digital devices.

• PROGRAMMING TRACK:  Many Digital systems require a ‘Programming Track’ separate from the rest of the layout on which to perform programming operations on locomotives.

• ROUTE:  The simultaneous operation of a series of points along a designated section of your railway.

• SPEED STEPS:  Controllable voltage increments which are used to control motor speed on a locomotive.  Some decoders allow the output power to be set for each speed step.  The range from zero to full power is divided equally into 14, 28 or 128 speed steps.