Model-Train-Help

Interesting Fact:

When driving a car, the yellow/amber light appears for a few seconds before the red light appears as a warning to prepare to stop. On a road the yellow/amber signal could be timed depending on a number of factors such as the volume of traffic and/or prevailing speed on the road the signal governs. The timing of the yellow/amber signal phasing is likely to take into account probable stopping distances for cars and trucks on the particular road.

Unlike trains; cars and trucks don't take as much time or distance to stop. Cars and trucks can also change direction to avoid a crash. That is why the yellow/amber warning light on road signals can be located on the same signal apparatus as the red danger light.

Trains, however, are heavy and take considerable time and distance to stop. Trains may require from half a mile, to a mile and a half to come to a complete stop. This is why, trains need a warning signal well before the point where they have to stop.

(note: road traffic laws vary from country to country so the exact meaning of a yellow/amber signal may vary depending on where you live).

How Does The Power Supply Work?

Most model trains run on low voltage. Unlike the AC electrical circuit in your house, the electricity that moves your locos is DC, ie. Direct Current. The supply to your layout comes by plugging a power pack (also called a transformer) into a wall socket that takes the AC supply, steps it down to the 12-15 volts needed to run the trains and up to 18 volts for the accessories.

The transformer converts the output to DC, filters the DC to purify it, then outputs the supply from the terminals on the back of your controller, along a couple of wires to the tracks where it is picked up by your locomotives wheels, turning the motor within. The throttle control varies the voltage to the rails, changing the speed of the motor and consequently the rate your locomotive moves down the track.

These lower step-down voltages are not usually dangerous, but it’s safest to attach wires to the terminals when the power pack is unplugged from the wall.

Regardless of how simple or complex the layout is, all model train operation follows one basic principle. You control the train speed and direction by varying the voltage and polarity of the electricity reaching the motor. You are in control!

Not all sets have a circuit breaker designed to provide protection by opening the circuit when too much current is being drawn from the transformer. The output terminals are low voltage A.C. power for the accessories and variable D.C. for the tracks.

There is a big choice when it comes to power packs. They come in a variety of designs to suit individual requirements. All power packs contain a few basic components, including a transformer to provide the 12 volts, a throttle to vary tile output voltage, and a direction switch to control the polarity of the circuit. Power packs also have screw terminals for the track (which is DC) and AC accessory connections.

Larger units may include a larger power supply as well as additional electronic features such as: operating modes, pilot lights and meters, and multiple terminals for accessories such as add-on walkaround throttle units. These units make it easier to operate your train, enabling you to follow it as it moves around the track, rather than standing in one spot and watching it.

Small layouts can get by with the basic power pack that comes with many starter train sets. Remember, that a starter set power pack probably won't have much extra power. Also, it may not have a circuit breaker to prevent burn-outs. If however, the locomotive you’ve purchased doesn’t have a powerful engine, then this type of power pack may be all you need to get started.

The pack that comes with a typical starter train set (rated as low as 7 volt-amps, or just 0.7 amps delivered at 10 volts) will run one (maybe two) locomotives at the same time.

Larger layouts or those with lots of accessories will require power packs with a larger power output. You can upgrade your power pack as your layout grows, using your older units to power accessories and powered turnouts.

Have the power you need. If you have a lot of accessories then you'll need to get a larger power pack or use multiple packs that can deliver powerful 18 volt amps of current. There's nothing more frustrating than not having the power that you need.

Electrical rating (measured in Watts or Voltamps (VA) meaning Volts x Amps) is what matters. Any pack will work on a big layout if enough feeder wires are attached to reduce electrical resistance and the resulting voltage drop that slows trains down as they get farther from the power source.

In order for a transformer to last a long time it should ALWAYS be operated within its rated capacity.

Let me explain. As already mentioned power can be measured in 'watts' which is calculated by multiplying ‘volts’ x ‘amps’ (Volts x Amps = Watts). Example: 10 volts x 10 amps = 100 watts

For reasonable performance of trains and accessories a power rating of 90 watts or higher would be desirable.

Let's now use a real example: A Lionel 1033 transformer has a rating of 90 Watts. Maximum load would be 20 volts output X 4 amps = 80 watts (approx.)

When a DC supply is used the calculation would be as described. For AC applications, it is close enough to help you figure the maximum load.

A quality transformer, when treated properly, should have a lifespan of 30+ years.

The golden rule is to ALWAYS operate the transformer within its rating. It is also important to keep the transformer dry and avoid damp areas (take particular care in basement locations).

When not using your train layout unplug the transformer. Don't walk away and leave it plugged in and unattended as it could start a fire. If a transformer gives off a burning odor, or expels smoke, heed these warning signs and immediately replace it or take it in for servicing.

A loud BUZZING noise coming from a transformer could be due to the transformer's core laminations moving. Servicing would be needed as this vibration can cause damage to insulation in contact with the moving metal.

A transformers circuit breaker can trip occasionally. If this happens simply unplug the transformer and let it cool off. The transformer will usually work again after it has cooled down. However, if the transformer continues to trip without a load, it will need servicing to fix the problem.

One more thing; NEVER use a transformer with a damaged, split, or cracked power cord. If in doubt have the transformer serviced immediately.

Electronic packs (or solid state) are another option. These packs give better control at lower speeds, especially as the train gets going. That's not to say that flywheels with heavy locomotives won't perform a similar function.

Acceleration is completely smooth when using an electronic pack. To get the motor started a simple burst of power is given out. The power bursts increase in frequency until straight D.C. is being fed through the motor.

With electronic packs it's possible to simply set the throttle at the speed you wish the train to reach and it’s all done automatically. Electronic packs provide a momentum, similar to the starting and stopping of a real train. An added feature is a brake switch that allows you to stop your train more quickly, rather than allowing it to coast to a standstill.

“If street lights or other accessories are dim or move slowly, it is most likely a transformer/power pack problem. There may be too many things drawing power. The solution is to invest in more powerful transformer/power pack to run the trains, or buy an inexpensive unit and use it only for accessories.”