# Speed steps?



## gator do 65 (Jan 27, 2014)

What is the purpose of the speed steps and there use?


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## wvgca (Jan 21, 2013)

same as having a dc controller without full variable movement,,, just click stops .. in dcc version, 14.28, or 128 steps or clicks ... not much uses 14 now, basic is 28 steps, some use 128 depending on your dcc controller options..
I'm assuming you mean actual 'speed steps', and not speed tables??which adjusts how much power is applied in each speed step..


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## DonR (Oct 18, 2012)

To amplify what WVGCA said; On a DC layout you vary the track
voltage to determine the speed of your loco. You reverse polarity
to cause it to back up.

The track voltage stays the same at all times on a DCC layout.
Each loco decoder responds to digital controller signals, 
converts the track current to DC and 'step' by 'step' 
changes the voltage to the loco motor to
increase or decrease the speed. The decoder also reverses
polarity to the motor to back up. All this has no effect on any
other DCC loco running on the track.

Some decoders have more steps than others. This makes possible a more
smooth speed change.

Don


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## gator do 65 (Jan 27, 2014)

Ok, I understand how DCC works! So I'll attempt to simplify my question.

How would speed steps be used in train ops i.e would you use 128 for switching and say 28 for mainline or is this just used as a legacy/backward compatibility for older decoders?


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## wvgca (Jan 21, 2013)

you can use either, what ever your decoder in the loco supports, most will do the 128 step .. i prefer 28, my max voltage is set to around 28 scale miles per hour, so one step gives one mph more for me


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## feldon30 (Dec 30, 2012)

I'm not an expert on this one, but here's my go:

Speed Steps are the granularity or number of levels of speed control. Think of how some automobiles have 4 gears while others have 5 or 6. A newer DCC decoder will support 28 or 128 steps for more gradual/smooth control, while an older decoder might only be able to do 14 and will have noticeable "steps" as more or less voltage is supplied depending on throttle position.

I can't think of any reason why you'd intentionally sets a newer decoder to use only 14 speed steps unless maybe you are trying to match it to a consisted engine of a different make. I think it probably comes down to personal preference on whether you use 28 or 128, as most people might not even notice the nuances between speed step #55 and #56. Do you do a lot of slow speed creeping?

If you do go with 128 steps, fortunately when you are adjusting the profile of your speed steps in your JMRI decoder programmer, fortunately you don't have to enter the numbers one-by-one (otherwise setting up 128 speed steps would take all day). You can instead adjust a curve and it interpolates new steps for you.

Again apologies if I have any errors in my post!


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## gator do 65 (Jan 27, 2014)

Thank you Folks for answering my question(s)!


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## Cycleops (Dec 6, 2014)

If your decoder supports 128 speed steps you'd be crazy to change it back to 28. More steps = smoother.


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## MrMoose (Dec 22, 2014)

I agree with using the 128 speed steps, if your system and decoder supports 128 speed steps then by all means use it. That will put your notches closer together and make for a more realistic acceleration and deceleration.


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## Cycleops (Dec 6, 2014)

Most decoders will automatically select 128 by default if enabled with this feature.


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## Mark R. (Jan 26, 2013)

This may sound odd, but I know one operator who using 14 steps in all his equipment. He has a good amount of momentum programmed into each engine, so there's smooth transitions between the minimal steps, and he has his top speed set down to the maximum the train can run on his layout .... which isn't very fast.

This way, his sound engines increase one notch with each speed step for the first eight steps which is usually in the normal speed range you are running.

It works surprisingly well, and much more realistic than I would have expected ! Real engines only have 8 notches, why do we need 128 ?

Mark.


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