If you found yourself on this page and are wondering what the difference is between AC, DC, and DCC, this may help. 

DC Power
DC (Direct Current) is the conventional method of powering most N, HO, On30, and G Scale trains.  The power pack supplies varying levels of voltage to the rails which, in turn, changes the speed of the locomotive.  To change direction, the polarity on the rails is simply reversed.  This works reliably and is fine for less complicated layouts and with few trains.  However, since you are really controlling power to the rails, any trains on the same rails will go in the same direction and cannot be controlled independently (ie - one cannot be stopped while the other is moving).  To work around this, track blocks can be created so that power to these isolated sections of track can be independently controlled.  This can lead to some complicated wiring and some confusing operation.  However, it can and is done.

DCC Power
This is a newer approach to model railroading and in a nutshell, works like this.  The concept of DCC (Digital Command Control) is that you are now directly and independently controlling individual locomotives anywhere on the layout.  To make this work, each locomotive must have an installed computer chip known as a decoder.  In contrast to how DC works, in DCC a constant voltage is applied to the rails at all times.  To make an engine move, your throttle and command station are used to send digital instructions via the rails to your locomotives.  Some of the benefits are that you don't need to worry about what block the locomotive is occupying, locomotives can act independently of one another, and with most decoder equipped locos, you can turn lights on and off.  Many are now also coming with sound capabilities that can all be controlled independently.  Because you don't need all of those blocks, wiring also becomes simpler.  Keep in mind that you cannot control DC engines on a DCC layout.

AC Power
Now, many O Scale layouts work on a 3-Rail system that is AC powered.  AC (Alternating Current) is different from DC in that the direction of current quickly changes direction at a high frequency.  Because of this, motors designed to be used on AC will not work with DC.  They need a different power supply.  Bachmann, Lionel, and MTH are examples of trains that require AC Power supplies.

Power/DCC/Electrical

Atlas - Switch Control Box

Atlas - Switch Control Box
Item #: 150-56
MSRP: $5.95
You Pay: $4.41
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Atlas - Selector

Atlas - Selector
Item #: 150-215
You Pay: $8.85
Product Details
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Atlas - Twin Connector

Atlas - Twin Connector
Item #: 150-210
You Pay: $8.85
Product Details
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In Stock
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Atlas - Controller

Atlas - Controller
Item #: 150-220
You Pay: $9.59
Product Details
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In Stock
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MRC - ThrottlePack® - AC Power - 0001301

MRC - ThrottlePack® - AC Power  - 0001301
Item #: 500-1301
MSRP: $139.98
You Pay: $101.71
Product Details
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Atlas - Connector

Atlas - Connector
Item #: 150-205
You Pay: $8.85
Product Details
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Atlas - Spade Connectors

Atlas - Spade Connectors
Item #: 150-201
MSRP: $6.95
You Pay: $5.15
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MRC - City - Country Sound Station 552 - AA552

MRC - City - Country Sound Station 552  - AA552
Item #: 500-552
MSRP: $75.98
You Pay: $55.44
Product Details
Discontinued
Only 8 left
Item Discontinued
8 In Stock for shipment w/in 1-2 business days

Bachmann - Switch Extension Cable - E-Z Track® -- 10' (green) - HO - 44598

Bachmann - Switch Extension Cable - E-Z Track® -- 10' (green) - HO  - 44598
Item #: 160-2513
MSRP: $16.00
You Pay: $11.90
Product Details
Not available. Add to Cart to Backorder.
Not Available. Add to Cart to Backorder.

Bachmann - Decoder-Equipped Nickel Silver E-Z Track® Turnout - HO

Bachmann - Decoder-Equipped Nickel Silver E-Z Track® Turnout - HO
Item #: 160-44130
MSRP: $66.00
You Pay: $42.13
Product Details
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Atlas - Complete Atlas Wiring Guide

Atlas - Complete Atlas Wiring Guide
Item #: 150-12
MSRP: $8.95
You Pay: $6.63
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Atlas - Layout Wire - Red 50 feet

Atlas - Layout Wire - Red 50 feet
Item #: 150-316
You Pay: $8.11
Product Details
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Atlas - Layout Wire - Green 50 feet

Atlas - Layout Wire - Green 50 feet
Item #: 150-317
You Pay: $8.11
Product Details
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In Stock
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Atlas - Layout Wire - Blue 50 feet

Atlas - Layout Wire - Blue 50 feet
Item #: 150-319
You Pay: $8.11
Product Details
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Bachmann - Interior Lighting Kit w/Wire pkg(2)

Bachmann - Interior Lighting Kit w/Wire pkg(2)
Item #: 160-42240
You Pay: $7.34
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Miniatronics - 12-Position Prewired Power Distribution Block -- Rated at 15 Amps

Miniatronics - 12-Position Prewired Power Distribution Block -- Rated at 15 Amps
Item #: 475-PDB1
MSRP: $26.95
You Pay: $22.48
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Tony's Trains - Card Edge Conn for Tortoise


Item #: TDS-TORTCONN
MSRP: $3.50
You Pay: $2.80
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Logic Rail Technologies - Block Animator - Infrared - TrueLens2

Logic Rail Technologies - Block Animator - Infrared - TrueLens2
Item #: LRT-BA-2-IR
MSRP: $49.95
You Pay: $47.38
Product Details
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Atlas - Layout Wire - Black 50 feet

Atlas - Layout Wire - Black 50 feet
Item #: 150-315
You Pay: $8.11
Product Details
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NCE - PCP - Spare Power Cab Connection Panel

NCE - PCP - Spare Power Cab Connection Panel
Item #: NCE-222
MSRP: $21.95
You Pay: $17.65
Product Details
Available
Available
Normally ships w/in 5 business days

Busch Gmbh and Co Kg - Building Light -- 14-16V pkg(2)

Busch Gmbh and Co Kg - Building Light -- 14-16V pkg(2)
Item #: 189-4280
MSRP: $4.99
Sale Price: $3.98
Product Details
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Normally ships w/in 1 business day.

MRC - Transmitter & Receiver - Light Genie - 025000

MRC - Transmitter & Receiver - Light Genie  - 025000
Item #: 500-25000
MSRP: $49.98
You Pay: $36.47
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Lionel - FasTrack™ Track w/Roadbed - 3-Rail -- Accessory Power Wires - O - 6-12053

Lionel - FasTrack™ Track w/Roadbed - 3-Rail -- Accessory Power Wires - O  - 6-12053
Item #: 434-12053
MSRP: $3.99
You Pay: $3.85
Product Details
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In Stock
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Bachmann - Decoder-Equipped Nickel Silver E-Z Track® Turnout -- #5 Left Hand - HO

Bachmann - Decoder-Equipped Nickel Silver E-Z Track® Turnout -- #5 Left Hand - HO
Item #: 160-44132
MSRP: $79.00
You Pay: $50.43
Product Details
In Stock
In Stock
Normally ships w/in 1 business day.