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DCC = Driving Carefully and Controlled ???


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Watching, and listening to a video on another thread of a DCC loco, set me thinking (which in my case requires a lot of effort)!

 

Before I continue I need to say that I don't (yet) have a layout let alone a DCC one, so what follows is observation, not criticism.

 

We've all seen layouts where locos go from 0-60 in such a short space of time that, scaled up, the G force would crush the driver and fireman against the bunker, or if running tender first, force them through the firehole.

 

Does being able to hear the simulated exhaust beat on DCC make it easier/force you to move off and brake more slowly?

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More likely that the sound project includes momentum settings that cause the loco to move off and brake at a realistic rate.

 

BTW my DCC sound equipped N Gauge Pendolino doesn't have an exhaust beat, more of a door closing beep, but it still takes time to accelerate and decelerate.

 

Hat,coat, I'm off.

 

John P

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1 hour ago, jpendle said:

More likely that the sound project includes momentum settings that cause the loco to move off and brake at a realistic rate.

 

BTW my DCC sound equipped N Gauge Pendolino doesn't have an exhaust beat, more of a door closing beep, but it still takes time to accelerate and decelerate.

 

Hat,coat, I'm off.

 

John P

So the acceleration/braking

is controlled by the chip, not

the operator?

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DCC allows you to set momentum characteristics that are applied to the chip, which means that you can't go from 0-60 in a fraction of a second.  I only have two DCC chips, but both are coded such that even if you whack the speed up to full, the locomotive will move off slowly and accelerate for some time before it reaches full speed.   You can of course set these configuration variables to zero (ie instantaneous response) if you want to continue high G force operation, but I'm not sure what impact that would have on a sound project if using DCC sound.

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Agreeing with what has been said before, DCC allows you to tailor the acceleration and deceleration to whatever suits you, plus the top speed and speed curve if you so desire.

Sound projects work much better when set with the higher values for acceleration and deceleration (or inertia/momentum if you prefer). Even the most basic DCC systems and decoders usually allow these things to be adjusted. Setting inertia and momentum to very low values, or zero, with sound projects really doesn't synchronise well.

I have quite a few sound locos and units, plus many more without sound, but I set all of them to use higher values for acceleration and deceleration, not just the sound ones. Sound projects usually come with high settings anyway, but i still tweak them further sometimes to get the characteristics I want from them.

Top speed is something that I also play with sometimes, particularly with small shunters and the like, where I don't want them to be able to do 150 mph. :D 

Speed adjustments may also be useful if you want to run two or more locos or units together. DCC allows you to match different characteristics more closely. In another topic there was a recent discussion on running multiple units together, and we got to Bachmann's class 150, which tends to have quite a low top speed, and Hornby's class 153, which has quite a high top speed. I haven't done this with mine (yet!), but the easy solution is to lower the class 153's top speed until it matches the 150 (which cannot be made to go any faster). 

I won't go into any further detail unless asked to, but I hope there is some food for thought in there, in mine and others' responses.

Edited by SRman
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1 hour ago, rab said:

So the acceleration/braking

is controlled by the chip, not

the operator?

 

With DCC, the “chip”, i.e. the decoder, is the controller.

The operator sends “commands” (instructions) to the decoder (the controller) and the decoder will control the loco/train against the operating characteristics and parameters (CV’s) set up in its memory.

 

 

Ron

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9 hours ago, rab said:

So the acceleration/braking

is controlled by the chip, not

the operator?

Yes, but the near-infinite adjustability (?!) of a DCC chip means you can have zero delay set, i.e. direct drive just like DC, or make the rate of acceleration glacial. And setting those parameters - including deceleration - to suit each loco's characteristics, is part of the satisfaction of DCC. 

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12 hours ago, rab said:

So the acceleration/braking is controlled by the chip, not the operator?

I will expand a little on this.

 

My major disappointment with DCC use at exhibitions, is how few operators properly utilise the available settings to mimic train inertia. With appropriately high settings, a locomotive can spend three or four minutes grafting up to speed, and the same sort of time slowing to a halt. Really smooth progress throughout, looks wonderful.

 

But operators will insist on driving under direct control, with low or zero settings for inertia. Arrive on the platform at 55mph, and at rest three or four seconds later. And rocket away, 0-60 in a time limited to supercars. That's not how trains move, and it's as much part of the modelling as the beautifully observed scene.

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3 minutes ago, 34theletterbetweenB&D said:

I will expand a little on this.

 

My major disappointment with DCC use at exhibitions, is how few operators properly utilise the available settings to mimic train inertia. With appropriately high settings, a locomotive can spend three or four minutes grafting up to speed, and the same sort of time slowing to a halt. Really smooth progress throughout, looks wonderful.

 

But operators will insist on driving under direct control, with low or zero settings for inertia. Arrive on the platform at 55mph, and at rest three or four seconds later. And rocket away, 0-60 in a time limited to supercars. That's not how trains move, and it's as much part of the modelling as the beautifully observed scene.

Perhaps they are trying to imitate those layouts with DC control?

 

It really is down to the builder of the loco. They choose what chip to put in. They choose what settings to use. Unfortunately most seem to change the address and nothing else. This is regrettable, as fine tuning the chip results in greater realism.

 

I won't comment on cheap chips that have limited adjustability.

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Of course it is quite possible with DCC a lot easier than DC, to have a loco start moving at a very slow speed step, in fact barely crawling along, and not needing to have momentum invoked - just let the driver increase speed by one speed step at a time - ideal when using 128 steps.

Getting a DC loco to start crawling very slowly to start with, needs the motor to be given a reasonably hefty electrical jolt - bit hard with standard DC controllers that increase track voltage - no problems with PWM controllers which can put out higher track voltage.

 

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3 hours ago, 34theletterbetweenB&D said:

With appropriately high settings, a locomotive can spend three or four minutes grafting up to speed, and the same sort of time slowing to a halt.

 

Seriously, how many layouts are large enough to do that?

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8 minutes ago, Crosland said:

Seriously, how many layouts are large enough to do that?

An insufficient number. ;)

 

It's the impression that the slow acceleration creates. As the train goes off scene, the mind 'paints in' extended acceleration into the imaginary distance.

Edited by 34theletterbetweenB&D
finger trouble
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46 minutes ago, Crosland said:

 

Seriously, how many layouts are large enough to do that?

beat me to it....on some layouts it will have been through the same station 3 times before stopping :)

Edited by pheaton
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41 minutes ago, 34theletterbetweenB&D said:

An insufficient number. ;)

 

It's the impression that the slow acceleration creates. As the train goes off scene, the mind 'paints in' extended acceleration into the imaginary distance.

only if you spend several scale days at the layout before you see it again :)

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A reasonable acceleration & deceleration makes driving trains more fun. Surely that is why we got into the hobby in the first place?

A while back, a friend of mine spent all evening trying to stop an EMU at the the end of the platform on my layout. He could easily have slowed it down earlier & crawled into the station, but wanted to leave it as late as possible. This is a little like what drivers of real trains have to cope with when trying to keep or recover time.

 

Some decoders go one step further (particularly sound projects on Zimo decoders) by including a brake feature. Deceleration can be set to a decent value for coasting & if you want to slow down, hit the brake.

I am sure I have seen this on a Loksound v4 decoder too.

I understand most non-sound Zimo decoders can do this but I have not worked out how to set it up. I am sure it is all in the manual :D

 

I find this a much more satisfying driving experience than turning a knob & seeing the loco instantly react.

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I agree, Pete. I have a few Zimo sound projects with the brake on F2 function. However, the brakes seem to me to be too effective, and I would like to make the trains take longer to stop if the F2 key is held rather than jabbed every so often. I'm sure this braking rate is also adjustable, but I haven't yet investigated this properly.

Going back to the high inertia/momentum settings, the first demos I did at an exhibition were done with a couple of lengths of flexible track along the front of our work/demonstration table. I had the Heljan Hymek fitted with Howes' sound (ESU v3.5) and had tweaked CV4 even further. Every so often i would overcook the Hymek, misjudge the braking distance and have to ask my fellow BRMA member sitting beside me to please rescue the Hymek from the desk top after I had managed to drive off the end of the tracks! :D

Edited by SRman
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I set my decoders with a custom curve to give a top speed the same as the prototype, but i set the bottom end  at around 5kph which is slow enough to be realistic but enough to 'kick' the motor into life - I then have the computer set too between 150 and 250ms per speed step which gives me a very realistic acceleration and deceleration and it brings the trains to a stop in exactly the same place each and every time they stop.

 

Quite a few people have commented upon how realistic the movement is  from stopped and also that the trains seem to go at the right speed for the landscape - I always take that as a compliment, even from the people who ask if I can make them go faster, or even crash! 

 

What I really enjoy is that because the computer controls it all I can enjoy my cup of tea watching my private model railway exhibition ;)

 

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I often go and play with a large dcc layout with a group of friends. The evenings are usually punctuated by a cry of 'sh!t, sh!t, sh!t' as a loco with lots of momentum dialled into its chip bears down on the train ahead at speed. Nine times out of ten a friendly hand will shoot out and restrain the runaway train whose wheels will scrabble round for a while until motion eventually ebbs away. Once in a while the loco evades capture and comes to rest in the back of the train ahead. All good fun. Of course DC layouts aren't immune to the need for speed getting out of hand but DCC shouldn't be regarded as a panacea.

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23 hours ago, Oldddudders said:

Yes, but the near-infinite adjustability (?!) of a DCC chip means you can have zero delay set, i.e. direct drive just like DC, or make the rate of acceleration glacial. And setting those parameters - including deceleration - to suit each loco's characteristics, is part of the satisfaction of DCC. 

With the shunting mode as digital function you can control by switch off/on acc./dec. in any time.

In fact it does loco controller who command.

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8 hours ago, SRman said:

I agree, Pete. I have a few Zimo sound projects with the brake on F2 function. However, the brakes seem to me to be too effective, and I would like to make the trains take longer to stop if the F2 key is held rather than jabbed every so often. I'm sure this braking rate is also adjustable, but I haven't yet investigated this properly.

I agree that most brakes seem to effective. I guess the programmers prefer to provide something you can see easily, then you can back this off if required.

 

I can't remember where I got this from & have not got around to trying it yet but I have the below in my notes:

 

CV346 is the braking rate for Zimo decoders.

CV179 is braking rate for Loksound,  I think I may have 1 decoder which uses this.

For both, a lower value for braking rate makes the brake weaker.

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Thanks for that information, Pete. I really must try it out. It can't really go wrong as long as I read the original values first, so I can restore them if it doesn't do what I want.

:drinks:

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2 hours ago, Neil said:

Nine times out of ten a friendly hand will shoot out and restrain the runaway train whose wheels will scrabble round for a while until motion eventually ebbs away. 

 

Does your system not allow emergency stop of the loco under control?

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