Up and running - a few questions

[Skier]

Hi All

I have just converted my layout to DCC.  I am somewhat staggered that it actually works first time - I thought I might have the odd short circuit or issue.  I am running an Elite controller with Hornby 8 pin decoders fitted to DCC ready locos.  I have a totally seperate programming section of track set up.

Having been with DC for many years I am finding the control under DCC very different.  My locos seems to take longer to get going and certainly a couple of them seem to make quite a loud humming noise on very low speeds.  So a couple of questions if I may,

Firstly how do I get the locos to "take off" a bit quicker?  I seem to have to turn the Elite control knob quite a long way up before the loco seems to move.  I know you can set Acceleration settings on the controller for my loco through my programming track.  

Secondly is the humming at low speeds normal - when I watch YT videos of other peoples DCC layouts I see locos moving at slow crawls in almost total silence.  

Sorry for the questions - this is all very new to me and I'm still amazed I've managed to set everything up so it actuallyworks !!

Regards

[96RAF]

The Elite speed knobs are rate dependant rotary encoders. What that means is the faster you turn the knob the more effect it has. Turn it slowly and you will be there all day. The thing to watch is the speed arc on the Elite screen. Practice rate dependant knob twiddling and watch the arc.

 

CV3 as you likely know controls momentum. A default of 5 is a normal steady pull away. A value of 0 will be boy racer starts. A larger value will porportionately take longer and longer to move to the set speed. Ditto CV4 for slowing down.

 

If the decoder allows change CV2 can be tweaked up to kick start a tardy loco.

 

CV10 can be adjusted from default 255 to zero to ingibit the point at which bemf (I call it cruise control) cuts in. This can affect slow running on some motors.

 

Give those a try in sequence and see what you can achieve.

[Chrissaf]

The factory default values for CV3 & CV4 in decoders are somewhat designed to provide an approximation to prototypical acceleration and deceleration. Thus slow moving off delays are totally normal in DCC compared to DC Analogue where everything is usually more instant in response to controller speed knob position. Sound decoders add even more delay before the loco starts to move.

 

You have to get your mind into a different mind set. With DC Analogue control the position of the controller knob is usually proportional to the power being sent to the track and therefore the loco motor.

 

In DCC the speed knob control has got nothing to do with direct power control of the track. The speed knob is telling the decoder how many speed steps to count through.

 

Most decoders are configured for 127 speed steps. In other words, the decoder steps through 127 power values to get from stationary to full speed. The decoder also uses the the Acceleration and Deceleration CVs to define the time interval between consecutive step increments. In other words, if the acceleration is slow then the rate at which the speed steps are incremented is also slow.

 

To further complicate matters, the Elite controller does not use a potentiometer control that is proportional to its position. For example, there is no end stop on the Elite knob. You can rotate it in circles at infinitum. The Elite uses a digital encoder control knob.

 

The Elite control knob measures the speed of rotation. If you rotate the Elite control knob slowly, the speed step increments increase at a very slow rate. If you want to accelerate more quickly then you rotate the Elite control knob more briskly. The actual position of the control knob is somewhat immaterial. Ignore the Elite control knob position and instead focus your attention on the black speed LCD bars on the display. You will notice that the faster you rotate the Elite control knob, then the faster the black speed indicator bars will increment. But you will also observe a lag. In other words, if you spin the Elite control knob very fast and illuminate all the black speed bars. You will still observe the loco slowly increasing its speed at the rate set by the Acceleration CV of the decoder.

 

You can change CVs to make the loco respond more instantly, but to do so is contrary to the original designers aim of trying to provide greater realism. Users that have never had a DC Analogue layout and went straight to DCC would probably feel that their experience of using DCC control is totally normal compared to yours. In time, I'm sure you will get used to the new way of control.

 

Decoders output a PWM voltage to the motor. Some motors are less tolerant of PWM and protest by making the buzzing noise. This buzzing is usually confined to when the loco is just beginning to move. Older non 'DCC Ready' locos that have been converted to DCC and draw more current than more modern 'DCC Ready' lower current locos tend to show this observation more.

 

PS - Congratulations on it working first time. We usually only get to hear about the users with issues. It is refreshing to hear a more positive piece of feedback.

 

EDIT: Rob posted whilst I was typing my long reply.

 

 

[Skier]

Hi All

Thank you so much for all your replies - these are very helpful.

Layout is progressing well.  Couple of issues on the curves with some strange track layout I had originally incorporated- I've now smoothed out the bends using second and third radius curves and converted my crossover to express points which has made the layout run and look better.  I've also rebuilt the track layout to my terminus station using express points for the initial approach and then Y points for the final splits into the platforms.  All points will be run off accessory decoders in due course.

Finding DCC great to run - had a couple of shorts, both caused by me firstly leaving a pair of pliers on the track and then by leaving a spare piece of track across one of the lines!!  Elite controller copes well and immediately shows "Error" and the red light - a search of the layout usually shows the culprit and then pressing the "Esc" button resets the system.

Regards to all.

[Flashbang]

HI

Pleased to read your getting used to DCC, which IMO is a far better control system than DC will ever be. (sorry die hard DC users, but the plain facts are out there!)   😮

What is very confusing to new DCC entrants to all this DCC Tech speak of CV and Values etc

So to try and make more sense of these - Consider CVs as the tuning slots as used on a TV or Radio to bring in a selected programme channel.  CV number xx allows you to select the operation within the decoder (The channel needed). Its value then allows you to Fine Tune that setting. e.g. back to our radio tuning - You select the frequency to be tuned (CV number) then slowly tune the setting to be able receive the best sound (Set a Value in that CV) 

So for the very basic item in DCC you need to select an address number (CV1) you then fine tune that number to ensure best reception) set CV1 value to the address number required.  e.g, CV1 value is set to 33. This becomes the decoders address number of 33. 

CV1 is of course a decoders address number and is frequently set automatically by the DCC system without the user knowing its been altered or set!

 

So, if you alter the value set in CV1 it will alter the decoder address number. If you alter say CV3 to a value of 1 the acceleration rate will be all but removed - The loco will move off immediately. If you then set CV3 to say a value of 30 the loco will take a considerable while to move off when the speed knob is set to a higher level.  Equally if you set the value in CV4 - de-acceleration rate to a high value number the loco will take a longer time to come to a stop when the speed knob is turned to Off.

 

So as you can see from the above, altering the values in a CV alters how the decoder and in turn the loco performs.

[RDS]

It is very much a personal choice but I have all my Loco's set to 14 Speed steps rather than the much higher value for exactly that same reason of having to keep winding the controller to get the Loco moving.

[Skier]

Hi 

Many thanks for your hel.

will have another play around with the ACC settings over the next few days.

Just one more question if I may - I have a diesel that starts off fine and crosses the first set of RH points perfectly.  However upon reaching the next set of points which are curved it stops dead only to then very slowly pick up speed and move off again.  It then runs perfectly over the points the next time round.  What could be causing this?  Wheel alignement on the point perhap?

Regards

[JemBobs]

Looks like bad contact somewhere. 

Check that your track is clean and that the pickups and wheels on the diesel are clean.

[Skier]

Hi All

Thought I would just give you a quick update on the layout.

DCC continues to be great and running well.  I've now changed some of my decoders to Lenz Standard V2 which makes my Hornby locos run smoother at low speeds. 

I have also now completed the track work by smoothing the remaining 2nd and 3rd radius curves and removing one of the curved points crossover - locos now seem to run more reliably around the entire circuit.

Finally I have started to sort through my older locos to ascertain which one's are going to be converted to DCC - I have already got three lined up with more to come.  I'm being realistic and not converting locos that I know struggled on DC control.  Going to mean a slim down of the collection but any funds raised will be reinvested in the layout for newer locos and scenery bits and pieces.

Regards