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Varible Engine Speeds,..automatic with DCC? Track and electrical/DCC
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Prolific poster 8,853 posts railandsail Prolific poster 8,853 posts
railandsail

Yesterday I was finally able to run some trains around the perimeter of the lower deck layout I am building. That perimeter track involves a few ramps up one portion of my viaduct, and down another. I was test running with plain DC power, and the trains would slow down quiet a bit while climbing, and speed up while descending. 

Does DCC operation do any adjusting of this engine speed automatically? ...or can it be programed to do so??

I am thinking that with longer trains and more heavily weighted ones than I was running this could really create problems if one was not on the throttle at all times?

 

 

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
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dennis461 Regular poster 165 posts
dennis461

yes, speed control

The short answer is yes.

Most every decoder (all I use) has adjustable speed control. It can be turned off or you can vary the intensity.

My locos have old 3-pole motors, they do not react to the control as well as I'd like.

 

Also, if you are running FULL throttle, the speed control cannot run the loco any faster.

i.e. lets say you are running half throttle,  the decoder sends 8VDC to the motor, on a hill (UP)  the decoder may tweak voltage up to 9VDC. At full throttle, 15VDC the decoder cannot adjust higher.
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barr_ceo Super User 3,297 posts
barr_ceo

... yes, a decoder can help.

... yes, a decoder can help. Read up on "Back EMF" in decoders.

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joef MRH Founder 17,535 posts
joef

Back EMF

Yes, as mentioned, it's called Back EMF or BEMF for short. You can tune it to be as strong or as weak as you need. It's kind of like cruise control for locomotives. However, some caveats. First, it can make running trains extremely boring if you crank up BEMF too much. Basically, the train runs the very same speed around curves, up hills, down hills ... it's so smooth you never need to touch the throttle. B-o-o-o-o-ring! Second, BEMF can cause real problems in consists if it's set too high -- in fact, the best decoders have a setting to turn off BEMF when consisting to eliminate this problem. If you have two locos consisted with BEMF turned on high, the locos will fight each other, causing extreme bucking. Basically, one loco sees the other loco slowing slightly, so it cranks up the speed to compensate. The other loco sees the other loco speeding up slightly and it cranks the speed DOWN to slow things down to compensate. Meanwhile the other loco was cranking the speed up to compensate for slowing and the other loco SLOWED DOWN in response! On consists, you need to either turn the BEMF way down, or turn it off. When setting BEMF, avoid the "cruise control" extreme. You WANT a train to slow some when going uphill or around curves -- that's just what the prototype does. You can use BEMF set to a light level to reduce the slowing -- but don't eliminate it entirely. That's not realistic!

Joe Fugate​
Publisher, Model Railroad Hobbyist magazine

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railandsail Prolific poster 8,853 posts
railandsail

Thanks very much guys, that's

Thanks very much guys, that's better than I thought might be available. I was getting concerned about the trains running too fast downhill after struggling to get uphill.

BTW was this something that Mike Wolf of MTH developed for his o scale trains and tried to patent??

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
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joef MRH Founder 17,535 posts
joef

Ancient history

Quote:

BTW was this something that Mike Wolf of MTH developed for his o scale trains and tried to patent??

That's ancient history and was based on a lot of confusing speculation. In short, nobody's really sure who said what and it just faded away finally. Waste of time to try and discuss it now.

Joe Fugate​
Publisher, Model Railroad Hobbyist magazine

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barr_ceo Super User 3,297 posts
barr_ceo

Not to mention...

...Completely pointless as MTH is gone....

Read my Journal / Blog...

!BARR_LO.GIF Freelanced N scale Class I   Digitrax & JMRI

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railandsail Prolific poster 8,853 posts
railandsail

BEMF

I only brought it up as I had a friend who had a big Lionel shop outside DC when Mike (in Balt) was introducing so many new things.  That's where I first saw the feature demonstrated (to the best of my memory?)

And if I recall Mike threaten law suits against other manufacturers. Did Broadway Ltd (or others) disable the BEMF features of their decoders,...on a temporary basis perhaps? Are their older decoders out there that still have their BEMF disabled??

 

EDITED: Well I see not all of my brain cells are shot. I found this mention of the QSI decoders that BLI was using at the time,.. https://forum.mrhmag.com/post/is-there-a-good-reference-on-the-controversies-around-mth-and-honmra-12209078
I'm actually amazed that I remembered that,.. considering I know so little about this DCC subject!

 

 

 

Brian

1) First Ideas: Help Designing Dbl-Deck Plan in Dedicated Shed
2) Next Idea: Another Interesting Trackplan to Consider
3) Final Plan: Trans-Continental Connector
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