Full Ring Bus or break it?

[Chrissaf]

I think I'll just butt out of this one and focus on driving on the wrong side of the road............ 😉

[Augustus Caesar]

Woah.... what's that big bright light with the word Chris stuck on it coming at me very fast... very VERY fast...

 

Get back on the other side man... 😮 😆

[2e0dtoeric]

Morse is of course a signal, manually modulated onto a carrier by the key  - - -

Sorry, but no! Morse, correctly referred to as CW, or Carrier Wave, is merely the presence or absence of the carrier wave. There is NO audio tone!

The receiver adds the tone itself, by oscillating when the carrier is present, and not, when it isn't! When you have heard CW n a pocket 'trannie', what you are really hearing is the CW 'beating' against some other signal, giving a false oscillation tone.

Morse is the name of the chap who invented the on/off code that is commonly used. There are others! It's original purpose was so that railway policemen (aka signallers) could talk to each other. It then became used for sending telegrams - via the policemen - to prosperous individuals!

So, see, it's not really too far off-topic as far as railways go!  :-)

[poliss]

Morse code as used in electric telegraph equipment was what I was referring too. The dots and dashes are similar to the way DCC works.

[Mumford]

Back to the OP  ( I thought Morse was a detective Cough)

 

Not fully understanding the technical reasons for and open or closed bus, I tended to follow the manufacturers instructions, for my E-Link I used a full loop closed bus. But when I was bought a Prodigy Express for Christmas, it did not like the closed loop one little bit, and kept shouting "shorts" at me, a quick snip through the bus wires to make them dead ended solved the problem.

 

I would love someone to explain that ( in simple terms) to me.

[poliss]

A ring bus will not cause shorts. An oval of track is a ring bus.

 

[Fishmanoz]

In fact, if all you did was snip each of the wires in your bus, nothing else, and that bus was previously running any loco successfully, I'm willing to put my hand up and say that cannot possibly change whether a loco causes an overload trip of your controller.  Something else must have happened to cause this.

[Chrissaf]

Another on-line information resource I have found regarding DCC Bus:

http://www.railwayscenics.com/pdf_instructions/dcc-power-bus.pdf

.

The link above can be found at the very bottom of this host page link below (contains more relevant info):

http://www.railwayscenics.com/dcc_bus_wiring.php

[poliss]

Yes, I've seen that. It says 'The general consensus is that a DCC bus should not be a continuous circle'. It doesn't say why the bus shouldn't be a continuos circle. Just because a lot of people say something doesn't mean it's right. The general consensus for gluing down ballast is to use a 50/50 mix of PVA and water, but it's wrong.

The page also recommends twisted pair wiring, which is fine unless you're using a current based block detector.

[Augustus Caesar]

Sometimes when I read articles like those linked to above and then see that the user or author of the document is also selling stuff I can become just a tiny bit cynical... why? Well, for one they may be honest and sincere, and in this case I think the author is, but on the other hand they are selling products for profit and do sell the termination filters if one decides to terminate a bus and not go for a ring bus after all.

 

My remarks are not to offend or be taken out of context but one or two may get my point. What I do find a little odd about this whole scenario is the fact that there are no absolute definitive 'must' or 'must not' articles where an absolute reason is not given for either argument.

 

However, all that aside, I do find one slightly odd thing in the article... it states that dropper wires should be kept to as short as 4 to 6 inches. Well, if your layout is two feet wide, like mine will be, and your circuits of track are on the edges of the boards, say two on the inside and one outside, then those droppers are likely to be about 12 inches long. So what happens there? Is he advising two rings or one ring and, well, bring the circuits closer together? While that may read daft to some of you I think it a perfectly decent question.

 

I'll be intrigued to find your answers to that. Would it be a case of just using a better gauge of wire for the droppers or not worry about the length being greater than six inches?

 

Just a thought....

[mjb1961]

Sometimes when I read articles like those linked to above and then see that the user or author of the document is also selling stuff I can become just a tiny bit cynical... why? Well, for one they may be honest and sincere, and in this case I think the author is, but on the other hand they are selling products for profit and do sell the termination filters if one decides to terminate a bus and not go for a ring bus after all.

 

My remarks are not to offend or be taken out of context but one or two may get my point. What I do find a little odd about this whole scenario is the fact that there are no absolute definitive 'must' or 'must not' articles where an absolute reason is not given for either argument.

 

However, all that aside, I do find one slightly odd thing in the article... it states that dropper wires should be kept to as short as 4 to 6 inches. Well, if your layout is two feet wide, like mine will be, and your circuits of track are on the edges of the boards, say two on the inside and one outside, then those droppers are likely to be about 12 inches long. So what happens there? Is he advising two rings or one ring and, well, bring the circuits closer together? While that may read daft to some of you I think it a perfectly decent question.

 

I'll be intrigued to find your answers to that. Would it be a case of just using a better gauge of wire for the droppers or not worry about the length being greater than six inches?

 

Just a thought....

Hi,,,,Dropper wire lengths ,,,take no notice ,I can't see what difference it would make apart from someone is going to say that you will lose current because they are too long ,I've got a full ring bus wire with at least 6 inch dropper wires and it runs a treat ,in fact it is better now than it has ever been ,my locos crawl over the points slow without stalling ,,,,I think your starting to over think the situation ,if you want a full ring bus then do it and add your droppers ,and get running some trains ,,,,,,mjb

[walkingthedog]

I think there is too much fuss made about voltage drop. Run a thick ish bus, thinner droppers so you can solder them to the track, done. 

 

It's a model railway not the electricity supply to a housing estate. Why does everything have to become so complicated?

 

DCC is supposed to be much simpler than DC, much less wiring, well that's how it started out. 

[poliss]

You're right WTD. There is too much fuss and a tendency to overcomplicate things.

I just did an internet speed test, and the ping from Newcastle to Carlisle and back again took 21 milliseconds. That's a bit longer than any DCC ring bus is going to be, so how it can affect the DCC data I don't know. A traceroute would probably say it went via Chicago too.

 

The late Teleman used 15 amp fuse wire to make the droppers. This is how he did his DC bus. That's DC, not DCC because what's a good idea in DCC holds just the same for DC.

[RDS]

... DCC is supposed to be much simpler than DC, much less wiring, well that's how it started out. 

 

Yes, you are right.  My layout which is 4 concentric ovals and 16 sidings in the middle with 32 sets of points, quite happily ran with just one connection to the outer loop.  Last year, after reading on here about having a bus and then wanting to make my layout more permanent, I fastened all the track down added a bus and lots of droppers.

 

I can honestly say, I have not noticed any difference, whatsoever!

[walkingthedog]

Sometimes when I'm at a loose end I consider about converting to DCC, but then think about all the pages and pages I read on here about filters, interference, voltage drops, decoders bursting into flames etc, then I have a glass if merlot and think, no.  😆

[poliss]

I just plug the controller into the track and run them WTD. No droppers, no bus, no writing macros.

The trains move as they should so no need to do anything else. You can get really complicated with DC too if you want to.

[walkingthedog]

I know poliss. Some people wallow in difficult solutions. My DC circuits have 3 or maybe 2  feeds each (can't remember) straight from the controller. Everything runs just fine. 

[Augustus Caesar]

@mjb

I don't think I am 'over thinking' the situation or problem re the wiring. To be perfectly honest, I have almost certainly made up my mind to do a full ring and keep the droppers the same gauge as the bus wires.

 

When I asked the initial question it was out of curiosity partly and mostly to see what the majority of members here use to do their systems in DCC. My last post dealt with a further 'anomoly' where one site author says use a maximum dropper length of 4 to 6 inches. Why? No need to answer that by the way!

 

There seems to be a general consensus that no ONE way is standard for this kind of hobby in DCC at least. I pick up on almost all that is said, read and digest everything, use common denominators, pull bits of info from elsewhere, tie the lot together and see if it would work on paper. So with the size of layout I gave that I have to work with I now know that one single bus, full ring possibly, droppers to as much of the layout as I can, but not wholly warranted maybe by others, gauges of wire to be used for ampages utilised and possible future expansion of layout, care taken where turnouts (mine will be electrofrog) need plastic joiners etc, care taken for lighting and other bits and bobs not mentioned above.

 

With all the usual advice and help I can now begin to get the wiring done (the bus first of course) and begin testing that to ensure I keep faults to a minimum and find them early if there are any.

 

I do believe that sometimes voltage drops may occur and interference may take place but without going ahead and ignoring that for the short term Iwill never know if I guarded against it unnecessarily or not. So I will leave that area aside for now at least and will revisit it when necessary. At least now I am aware of it.

 

Once I have a couple of circuits going and all is well then I will come back with more stuff on voltages where a higher ampage may be required... LEDs and so on... so be prepared everyone!

 

I will continue to read this thread and input of course if anyone adds further information. For now guys... all of you...

 

Thanks again for all your help and advice! If I was as good at this side as I am with computers I'd be a genius... well, maybe not. 😎

[RDS]

&AC

Sound great.  I look forward to hearing your progress.

(My droppers range in length from about 50mm to maybe up to 300mm)

[Fishmanoz]

Think about it this way - a perfect bus would consist of wire of zero resistance to avoid voltage drop, twisted to shield it from picking up stray interference and with zero length droppers to avoid resistance and interference.  No real bus can be like this and each will have its own resistance and interference pickup which can be minimised by design with heavier wire, twisted, and droppers kept short.  As droppers are made longer, they too will need heavier wire gauge and, at the extreme, you could twist them too, treating them as another arm on a radial bus.

 

Now think about a ring bus.  If you were to take this, hold it at the point where it connects to the controller and at the point half way around and stretch it out, what you'll end up with will be a linear bus with duplicated wires and not twisted. Now as you put it back into the original shape, those duplicated wires separate and the potential to pick up interference increases.  This seems to me to be the reason it might be better not to do it.  In practice, if there is no interference around, it will make little or no difference though.  Also, I can see no reason why you can't include a terminator half way around a ring.  It's purpose is to dampen spikes which may arise on recovery from a short and it doesn't need to be at the "end" to do this.

[Augustus Caesar]

@RDS

The only thing keeping me from 'making that start' is my business and all that goes with it.

Now is usually a quiet-ish time so maybe I can get things moving... fingers crossed. What I am looking forward to is putting some of these suggestions into place so watch this space... don't expect toomuch though 😉

 

@Fishmanoz

Plenty food for thought there with the objective view you give. Worth taking into consideration.

We'll see how I start and get on... one thing about interference here is there is very little if any. My server and router (some wireless hardware too) don't play havoc thus far so all should be well as they are out of the way. Outside issues don't arise.