Power Bus Wire

[Guest]

On 10/08/2019 at 11:10, RobjUK said:

 

I am a "digital expert" - I've been designing & consulting in electronics for manufacture for over 40 years, including high speed digital systems & I've worked with everything from digital signal processing & radio data links through multiple hundreds of kilowatts power controls.

 

I am also extremely familiar with transmission line effects that can cause problems in some kinds of systems.

In transmission line terms, an open end with no termination or load is generally the worst case for causing signal reflection & distortion problems.

 

In strict transmission line terms, every joint, transition or tap in a wiring system causes signal reflections, unless it is very accurately designed and the cable (and connector) impedances properly matched.

 

No one considers such things with any other part of the power wiring interconnections for a DCC setup, yet then are no less relevant than the bus ends being linked as a ring.

 

 

Suitability of any particular wiring / connection scheme depends totally on the application.

For a multiple-interconnected system like a typical DCC & track setup with numerous droppers off the main bus and multiple cable / track stubs, you have no more - or less - chance of suffering signal distortion with a ring config than an open end.

 

The whole subject is a non-issue and just confusing or worrying people who do not understand the technical details.

 

 

DCC uses a modulated data system (not raw binary) and has error checking in the data demodulation routines, so occasional corrupt data frames do not cause problems.

 

It was & is specifically designed for electrically noisy systems.

 

I am a digital expert too since when Märklin and Lenz did present theirs digital system.

I have been learn to understand what and how digital communication works via the rail.

We call it zero and one that are binary codes to control locomotive/ accessories device via central station.

You will have digital interference by connect a ring system when you use digital system.

I always use a split system and have never ever problem.

To use Power Bus wire i recommended a split system by use a common connection by divided up feeder wires to the rail every second metres and to feed the digital accessories.

Never ever use a ring system is mine recommended.

 

[RobjUK]

14 minutes ago, Anders63 said:

I am a digital expert too since when Märklin and Lenz did present theirs digital system.

 

Sorry, no!

Just using someone else's products does not automatically make you an expert on the fundamental principles of of how they work.

There is a massive difference between just knowing how to use a gadget and knowing how to design that same gadget.

 

Have you ever written a DCC decoder program from scratch, so fully you understand the data modulation and coding? 

 

15 minutes ago, Anders63 said:

I always use a split system and have never ever problem.

 

So how do you know there would be problems if you _did_ properly make it in to a ring, with no shorts as a result?

 

Again, it's a meaningless statement.

It's like someone claiming they have proof a "lucky rabbits foot" works because they always carry it and have never been struck by lightning.

 

You need direct evidence of cause and effect for claims to be meaningful.

 

[Guest]

1 hour ago, RobjUK said:

 

Sorry, no!

Just using someone else's products does not automatically make you an expert on the fundamental principles of of how they work.

There is a massive difference between just knowing how to use a gadget and knowing how to design that same gadget.

 

Have you ever written a DCC decoder program from scratch, so fully you understand the data modulation and coding? 

 

 

So how do you know there would be problems if you _did_ properly make it in to a ring, with no shorts as a result?

 

Again, it's a meaningless statement.

It's like someone claiming they have proof a "lucky rabbits foot" works because they always carry it and have never been struck by lightning.

 

You need direct evidence of cause and effect for claims to be meaningful.

 

My first contact with a digital system was year 1986.

Since then i did used only digital layout.

And yes i did myself mistake by use a ring system which did result to digital interference.

I did asked to digital experts like Märklin and Lenz what the problem was.

I learned my mistakes and become more expert.

I recommended other by use split system with a common connection.

To write a DCC decoder program you need work toy like experts do have for exemple electronic company who are produce decoder for the model railway.

I don´t understand why you write meaningless statement, when you know yourself the rules about digital system and to code?

[RobjUK]

1 hour ago, Anders63 said:

And yes i did myself mistake by use a ring system which did result to digital interference.

I did asked to digital experts like Märklin and Lenz what the problem was.

I learned my mistakes and become more expert.

 

Sorry, but a single experience of a problem could have many reasons. Blaming it one one specific thing without technical facts is superstition, not science. 

 

If working with a properly impedance matched and terminated transmission line system, the rules would be totally different - but a DCC power distribution and track setup is none of those things.

The more stubs and cross connections between power wiring and tracks, the nearer it gets to acting like a simple capacitive load.

 

 

1 hour ago, Anders63 said:

To write a DCC decoder program you need work toy like experts do have for exemple electronic company who are produce decoder for the model railway.

 

No, that's silly.

Is all the MERG software written by people who work for decoder manufacturers? No..

 

Like many electronics enthusiasts, I write software for things like that and build electronics to try things out for fun. It is just interesting in its own right - knowledge is its own reward.

(As well as me doing it as a profession, on a rather larger scale).

 

 

Anyway, I do not like arguing. It's a waste of effort & probably annoying to other users.

Various people on here have said they use ring-connected systems without problems; if there was any genuine,  fundamental problem with a ring those setups would not work.

 

 

[traction]

It always makes me smile when people say you can't or shouldn't use a ring main as the power bus.

 

All of my layouts are using a ring bus as all of the layouts are complete ovals, never been an issue, if it was I wouldn't do it.
Seems rather backwards to have a radial bus if what you're connecting to is a complete ring!
Although I could be missing the blatantly obvious.

 

Cheers

 

Ian

 

 

[Junctionmad]

at DCC speeds, there is no drawback to using a ring and in fact it has some advantages in current distribution.  Those advocating it will cause so called " digital interference " simply dont understand a word of what they are talking about 

Edited August 12, 2019 by Junctionmad

[Crewlisle]

My compact 2.5M x 2.3M 00 gauge DCC layout ‘Crewlisle’ is on four baseboards with three levels  - high, middle & reversing loop on the low level & uses Lenz LH90 handsets & LZV100 command unit.  For the track bus I use 6 amp cable with both wires twisted together & at baseboard joints I use two single pole 4mm banana plugs & sockets.  The male pins are slightly tapered & sprung & when fitted in the adjoining socket it provides a tight, positive joint - no chance of loose connections as sometimes happens with double or multi  pin plugs.  Over the last ten years the layout has been dismantled/reassembled more times than I care to remember with no electrical problems whatsoever.  All my droppers are connected to the track bus by simple 5A screwed terminals (available from any good electrical spares shop, eg B&Q).  Before screwing them into position, note what sections they serve on a piece of card either by hand or on a computer & mount it behind the terminals.  If there are any power supply problems it is easy to identify the offending section by removing each lead in turn.   

After a while I realised that if there was a short anywhere on the layout, the whole layout would automatically shut down; embarrassing if you are at the NEC with many people watching!  To allow operation to continue on half of the layout when there was a short, I installed two PSX-1 units on two separate track buses – one for the high level & one for the middle level including the low level reversing loop Lenz LK-100 Reversing Module.   During initial testing a loco would leave the mid level, enter the reversing loop, LK-100 module relays would ‘chatter’ & loco would come to a halt.   After posing the question on RMWeb I was not given the answer but a good clue how to solve it.  What was happening was that the PSX-1 & LK-100 were fighting against each other on changing track polarity.  To solve the problem I reconnected the LK-100 module directly to the back of my Command Station before the power take off supply for the two PSX-1 modules.  Since then I have had no problems.

By today's standards, my set up is prehistoric!  Why complicate things with so much technical jargon & put people off from converting to DCC?  If it ain't broke, don't fix it!

 

Peter

[Sir TophamHatt]

I used an end-to-end bus on my last layout.

I use a ring on this layout.

 

I have noticed ZERO difference in terms of response to my locos.

Therefore I will always believe (unless I notice any different) that using either is fine and it's not worth arguing over whose... um... knowledge is bigger than whose.

[Crosland]

23 minutes ago, Sir TophamHatt said:

I used an end-to-end bus on my last layout.

I use a ring on this layout.

 

I have noticed ZERO difference in terms of response to my locos.

Therefore I will always believe (unless I notice any different) that using either is fine and it's not worth arguing over whose... um... knowledge is bigger than whose.

 

Agreed, but it is always worth debunking the myth that rings are always bad.