Booster
DCCWiki, a community DCC encyclopedia.
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Responsible for combining the intelligence from command station with the power from the power supply. |
The booster is sometimes referred to as a the "Power Station". Since the booster contains no intelligence (non-thinking), it can be thought of as the "Pack Mule" of a DCC system as it is responsible for combining the intelligence from the command station with the power from the power supply.
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[edit] The Booster's Purpose
The booster takes digital level signals supplied by the command station and combines them with power from the power supply. The output from the booster is a DCC waveform applied to the rails to control and power the locomotives equipped with decoders. You can also optionally connect to the track power stationary decoders to control devices like track turnout switches.
Note: electric turnouts should be connected to a seperate booster, or at least through a power management device. See the Turnout Control page for details and explanation.
[edit] Combinations
Sometimes the command station and the booster are combined into one unit to make setup simpler. Typically, your first booster is combined with the command station, however, additional power supplies and boosters can be added to larger layouts, or layouts needing additional power such as garden railroads.
[edit] One Active Command Station Only
Remember, there can only be one command station active on a layout at any one time. If you want to use a combined command station/booster on a layout as a simple booster, you must be sure the command station functions of any additional units are inactive.
Some command stations will switch to booster function automatically if they detect another command station on-line. (In this case, turn the command station unit on a few seconds before the other units!) Others need to have this done through some kind of manual procedure.
A few command station/boosters cannot be used as booster-only units.
Check your unit's documentation for details!
[edit] Booster Power Regulation and Protection
Boosters are responsible for the following tasks:
1) Convert the incoming AC or DC power into a local internal DC power source suitable to drive the track.
2) Provide current limiting protection so that any short circuit current is within safe limits of the booster abilities.
3) Optionally provide a regulated voltage for the track.
4) Provide an automatic resetting "Circuit Breaker" protection function to limit the total power when a sustained short circuit occurs.
5) Convert the command station level DCC signals into a DCC track waveforms with suitable volts and amps to run locomotives.
[edit] Booster Size (Amps)
A booster's capacity typically ranges from 2.5 amps to 10 amps, most are around 5 amps.
N and HO scales should not use a booster greater than five amps without some sort of power management device in place. This allows 8 amp boosters, but limits the maximum current to the power districts at a lower level. This protects your trains and their decoders.
It is unlikely that all of your locomotives will be in the same power district at the same time, so a 4A or lower trip point will not cause any problems.
O and G scales should use the eight-amp boosters, along with some power-hungry S Scale systems
If the layout gets large enough to run lots of trains, you can have as many boosters as needed to run all the trains. N-Trak has run extremely large layouts with dozens of boosters controlled by a single command station.
[edit] Additional boosters
You might think it's best to have a single, large, booster to power your entire layout. However, you will soon learn, it's typically best to have a couple smaller boosters distributed around your layout. The reasons include: Additional trains, reverse sections, and isolate derailments.
[edit] Adding Boosters
To add additional boosters, you will need to electrically divide your track, and connect a new booster to that track. The booster may need a separate power supply, and must be connected to your DCC system's booster bus. By connecting the booster to the booster bus, all boosters on the layout will send out the same commands to all sections of the track. This allows trains to recieve commands, even if they are crossing between power districts controlled by different boosters.
Suggestion: Be sure to double gap the tracks to fully isolate the boosters. That is, both rails need to be cut at the same spot.
Warning: Do not wire boosters in parallel. This will lead to melted plastic and fried boosters. You cannot simply wire them in parallel. You must connect separate sections of track to separate boosters.
Caution: Read and follow the manufacturer's directions for the booster and your DCC system on how to properly wire an additional booster.
Common Ground: Be sure to wire a common ground between boosters. This way they all have the same reference point for ground. Power management devices may also require grounding to the command station or booster.
[edit] Additional Locomotives
A booster is rated for amount of current it is capable of delivering to the track. If you demand more current than it can supply, it will simply shutdown.
If you notice the trains starting to slow down when multiple trains are running, that's a sign you are reaching the limit of your booster - it's time to add additional boosters.
Typical boosters deliver 4 to 5 amps, and can be as high as 10 amps. This may be enough to run a train or two in the garden, or almost a dozen HO or Z scale trains.
[edit] Reverse Sections
Please see the main article on Reverse sections.
[edit] Isolating Derailments
Sooner or later, a train will derail causing the booster to go into protection mode.
Once this happens, all trains using that booster will come to an immediate stop. If you want to prevent a derailment, say in a switching or staging yard, from stopping all the trains on a layout, power these sections with a seperate booster. This way, if someone accidentally shorts the tracks while putting locos on the tracks, the rest of the layout will continue to operate.
[edit] Alternatives
There are alternatives for adding boosters to get the above listed features, except for adding a booster for additional power.
If all you need to do is isolate a small section of track, or run one or more Reverse sections, then you can use power management modules found from various manufacturers.
These modules typical go between the booster and the section of trackage.
For example, a reversing power module would connect between the booster and a reversing section, but the rest of the track is still powered directly from the same booster. The moment a wheel connects between rails of different polarity, the reverser springs into action and makes them both the same polarity. A typical application would be a reverse loop.
Some power management modules can take a single (or multiple) input, and provide multiple outputs. This splits up your layout into several blocks using a single booster.
[edit] Power Supply Considerations
[edit] Enough power
Make sure that your Power supply can supply your booster adequately. That is, make sure the power supply 'outputs at least the same current your booster can handle. For example, if your booster can handle 8 amps, make sure your power supply can supply at least 8 amps.
It's best to not use your old power pack as it may be insufficiently rated for your booster to operate properly.
Many people want to 'recycle' older equipment, but it's generally better to buy a properly sized power supply. The reason: boosters can typically output more current than DC (analog) operations needed.
With DCC, you can operate many trains at the same time from one booster, where DC used multiple power packs with a block system to route power.
As such, the booster can output a lot more current, and it needs more available current to function properly.
If an inadequate power supply is used, the booster's current protection will fail to work during a short. This can result in something on the track getting very hot, possibly melting or even catching on fire. So, avoid letting the magic smoke out of decoders and locomotives by using the right sized power supply. It may also result in overheating and unexplained shut downs.
[edit] One Power Supply, One Booster
For many of the same reasons above, connect only one booster per power supply. Always follow the manufacturer's manual.
[edit] No common rail
- Main article: No common rail wiring
Do not use common rail wiring! Please see the main article for details and full explanation.
