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DCC Track Power 1

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    Posted: 05 May 2013 at 3:55am
This is truly a difficult subject to elaborate on, especially if you address lay persons. Between myself and Buddy BR42, I collected some data. I will not complete this issue in one session.

First off, let us go to the old analog (conventional) operation.

It has been explained that the 12 Volt DC 2-rail system applies about 12 Volt DC (direct current, namely + (plus) and - (minus), to the tracks.

The AC 3-rail system (Maerklin HO Scale and Lionel O-Scale), in turn, applies an AC (Alternating Current, 60 cycles per second, 60 Hz, which is pronounced Hertz, like the Car Rental Company Herz). This type of electricity changes its polarity 60 times a second. On an Oscillosope it shows up as a sine wave. It is like going up a steep hill, going over a rounded top, then fall down into a valley, a rounded slope to the bottom, then back uphill, etc etc.

Imagine a roller coaster. You start at ground level. You go up to the top, then down into the valley, dug into the ground to the same depth as the above peak, and back up to ground level. Be sure you have a barf bag with you. This is one cycle. If you do this 60 times per second (60 Hz) you will know what the household AC does, if you survive.

Now, you switch to DCC (Digital Command Control). Uffda!! That is when things become quite complicated.

First off, it does not matter whether you use Maerklin or NMRA norms. Both basically use the same approach to this.

In either case, the track power applied is a form of AC.

The first difference is the wave shape. It is not a sine wave, as described above. It is a Square Wave. So, what the heck is this? Oh well!

Imagine a mountain climber. Up a vertical wall. Once the top is reached, you walk on level ground, for a distance. Then comes the vertical down cliff. Follow above described roller coaster path. You get it? That is a squarewave shape.

The next difference is the frequency, meaning how often does this occur.
From the Household Current we learned that a full cycle occurs 60 times per second, namely 60 Hz.

Whatever DCC device you use, it sends the squarewave at a much higher frequency, depending on the system you are using.

It is usually in the vicinity of 10,000 Hz (10 kHz).

Under certain conditions, it will be greater than that.

This is enough for this session. To be continued.
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