# what is a



## ronnie (Jan 20, 2014)

decoder?

Ronnie


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## Big Ed (Jun 16, 2009)

A decoder is a device which does the reverse operation of an encoder, undoing the encoding so that the original information can be retrieved. The same method used to encode is usually just reversed in order to decode. It is a combinational circuit that converts binary information from n input lines to a maximum of 2n unique output lines.


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## D&J Railroad (Oct 4, 2013)

A model railroad decoder is a device that fits into a model locomotive, between the track and all the components under the loco shell, i.e. motor, lights, speaker, smoke unit etc.
The most common decoder is of the Digital Command Control family of components and can either be a mobile decoder, rides inside a moving peice of rolling stock or a stationary decoder, i.e. a turnout controller. The function of the decoder is to take the commands (packets) of the command station or throttle and convert them to control functions in the rolling stock or stationary decoder. 
Mobile decoders can be an inexpensive basic decoder that only controls the motor of the loco and a couple of light bulbs for the headlights. More expensive decoders will have control of the motor along with numerous lights or LEDs, sound systems and speaker and smoke units on steam locomotives.


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## NIMT (Jan 6, 2011)

Understanding DCC
http://www.dccwiki.com/Introduction_to_DCC


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## golfermd (Apr 19, 2013)

As an addition to what has already been said, the "encoded' data packets (commands sent by your throttle) are actually put on the track. Just as the metal wheels pick up the electricity to power the DC motor in your locomotive, the wheels pick up the electricity from the track, which is now in AC and has the data packets in it, and goes straight to your decoder. The decoder does several things. First, it strips off the data packet for decoding (all those commands), and then converts the AC power to DC so your motors work properly. That's why you can take a DC locomotive and convert it to DCC. As far as the motor is concerned it is getting DC power from the track.


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