Over/under figure 8 layout. Constant speed DC HOW?

[Chris333]

I have asked about this before, but never built anything so never dug into it. Now I have built something  An over/under figure 8 layout that only has about 6" worth of flat level track. Up hill is ~4% and down is ~4.5%. It will be a display layout that just runs in circles. Assuming that up hill is the highest speed how do I slow the train going down hill?

I was thinking to cut gaps in the rail and add many sections with different resistors, but I though someone here was talking about a feedback controller that would take care of it all.

Any ideas?

[Mike C]

  Decoder BEMF ?

[Chris333]

DC. Just one C.

[Point353]

I have asked about this before, but never built anything so never dug into it. Now I have built something  An over/under figure 8 layout that only has about 6" worth of flat level track. Up hill is ~4% and down is ~4.5%. It will be a display layout that just runs in circles. Assuming that up hill is the highest speed how do I slow the train going down hill?

I was thinking to cut gaps in the rail and add many sections with different resistors, but I though someone here was talking about a feedback controller that would take care of it all.

Any ideas?

http://www.circuitron.com/index_files/ins/800-5601ins.pdf
https://www.modeltrainstuff.com/circuitron-800-5601-as-1-automatic-slowdown-circuit/

[peteski]

If the DCC decoder's motor driver still uses BEMF when being operated on DC (I don't know if that is the case), then installing a decoder, programming it with the appropriate settings, then running it in DC should result in constant speed.

Second thought: A real train climbing a hill will also slow down, so just leave it as-is to be realistic.

Third thought: instead of using electrical solution (like BEMF feedback) use a mechanism with high gear ratio, and a powerful coreless motor. That design should not be affected much by the changes of its load.

[Chris333]

http://www.circuitron.com/index_files/ins/800-5601ins.pdf
https://www.modeltrainstuff.com/circuitron-800-5601-as-1-automatic-slowdown-circuit/

I have a feeling it is more than a fast and slow section. When I control the trains speed with the power pack knob it takes a lot to keep it steady. Once the train is on the grades it stay even for a short while, but reaching the top or bottom needs feathering.

But if it would do all that I'd give it a try.

[Chris333]

If the DCC decoder's motor driver still uses BEMF when being operated on DC (I don't know if that is the case), then installing a decoder, programming it with the appropriate settings, then running it in DC should result in constant speed.

No decoders and I sold my DCC system about a year ago after never using it.



Second thought: A real train climbing a hill will also slow down, so just leave it as-is to be realistic.

Sorry this is why none of my layouts have ever had a grade. I can't stand the fast-slow cycle.



Third thought: instead of using electrical solution (like BEMF feedback) use a mechanism with high gear ratio, and a powerful coreless motor. That design should not be affected much by the changes of its load.

Well that does work. I have a Heisler with a very high ratio that runs pretty good and might get by with only 2 speed zones, but I can't just run that same $700 locomotive all the time. And while I would love to add high ratios to every thing else that just won't fit.

[Chris333]

What about this controller?
https://www.gaugemasterretail.com/magento/model-railways/gaugemaster-controls-brand5/gaugemaster-gmc-hh.html

[Point353]

What about this controller?
https://www.gaugemasterretail.com/magento/model-railways/gaugemaster-controls-brand5/gaugemaster-gmc-hh.html

How would that unit, by itself, "slow the train going down hill" as you mentioned in the first post?

[Chris333]

How would that unit, by itself, "slow the train going down hill" as you mentioned in the first post?

I found this about it:

Hand Held controller fitted with feedback electronics to maintain a constant speed when travelling up and down inclines. GMC-HH : Single Track Hand Held Controller with Feedback

[Chris333]

Pics make a thread better 

[learmoia]

The 2 ideas I can think of:
1: DCC Decoder with BEMF.. Decoder under the layout, not in the locomotive.
2: Split the layout into 2 districts.. uphill and downhill... put a throttle on each and tune the voltage independently to get the constant speed you want

[peteski]

The 2 ideas I can think of:
1: DCC Decoder with BEMF.. Decoder under the layout, not in the locomotive.
2: Split the layout into 2 districts.. uphill and downhill... put a throttle on each and tune the voltage independently to get the constant speed you want

Yes, either way, under the layout, or in the locomotive (and in either case powered by DC voltage).

Chris you don't need a DCC system - like I  said, you would be running a DCC decoder using DC power, using that decoder as a BEMF equipped "throttle". That is assuming that the same BEMF functionality is applied to the motor driving circuit while decoder is running from DC power.

[Chris333]

Well if you know of such a decoder...

I ran some locomotives with the meter attached to see what was going on. I'm not sure I understand it though.

Loco1 going up hill @4.6V when it gets to the top the meter reads 5V, then while going downhill @5.6V

Loco2 (high geared Heisler) 7.6V up. 8V top. 8.2V down.

So why is the voltage increasing when the loco is going down hill and presumably doesn't need as much power?

Using a Rokuhan  RC-02  http://www.zscalemonster.com/rokuhan/accessories/

[Chris333]

I think at minimum I'd need at least 4 different speed zones like this:


It is possible the green and blue areas might end up the same. So what about my original idea to wire resistors to the green and yellow areas? And use the red area as the control.