What am I doing wrong ?

[TheGhostofNigelGresley]

Hello Folks,

 

I thought I would be clever and have built a 6ft by 4ft oval which is hinged in the middle for space saving purposes. It isn't clever, it doesn't work. A wagon will jump over 'the join' between boards as if it wasn't there, but a loco will not, it stops and only one half of the oval has power.

 

Each board has 4 pieces of track each of which has power via a dropper and a Bus which goes all the way around. It would seem that the power is going up to the 'gap' (very small) and instead of carrying on along the Bus wire it seems to be returning to the controller through the track, thus powering only one half of the oval ?

 

Any idea what is going on and how do I fix it ?

 

Words of wisdom greatly appreciated, as I am now officially without clue :-(

 

Chris.

[Nearholmer]

A very tiny gap is all that it takes to create an ‘open circuit’.

 

You should have two wires to each board from the controller output terminals, one connected to the inner rail of the oval, one connected to the outer rail. 
 

The two wires that go to the two inner rails (one on each board) should be connected to one terminal of the controller, the two wires going to the two outer rails should be connected to the other terminal.
 

Is it connected-up like that?

[TheGhostofNigelGresley]

No Sir, it is not.

 

Thank you very much for your time - what a wonderful resource these forums are for the idiot  beginner. I'll try that and report back in a few days, once I've had the chance to tinker.

 

I can feel the Slough of Despond lifting already...

 

C.

[Robert Stokes]

The previous answer is correct but you don't need separate bus wires for each half of the layout going to the controller. You could have one pair of bus wires which go round the whole layout providing you leave enough slack in the cable that crosses the junction so that when it is folded it doesn't break the wires or even pull them too tight.

[Nearholmer]

My thinking was to start really simply, then build-up from there.

[TheGhostofNigelGresley]

Ah,

 

The fog rolls back in. 

 

Forget an oval, call it a clock face. The split is between 12 and 6 o'clock. The power enters at 5 o'clock and goes anticlockwise all the way around until 7 o'clock, leaving appropriate slack to allow the fold. Droppers are wired to each piece of track outside and inside rail, rail joiners are used on every joint bar the 'jump' between boards.

 

Only the right hand board has power.

 

Where it's going wrong is after 7 o'clock, how does the  bus finish ?

 

I'm actually starting to enjoy this !

 

C. 

[Robert Stokes]

The bus entering at 5 o clock should provide power back to 6 o clock. The bus wire ending at 7 o clock should provide power up to 6 o clock. This means engines should get power all the way round. Given that, it is difficult to work out what is going wrong. Do engines actually run from just after 6 o clock all the way round to 6 o clock but then won't cross the gap. Or do engines also refuse to cross the 12 o clock gap?

 

I'm going to bed now, so won't see your reply until tomorrow. It will be interesting to see whether anyone (including you) has worked out what is going on by then.

 

P.S. The bus wires at 7 o clock just end. They should not be connected to anything. In fact they need not go past the last set of droppers.

Edited October 27, 2021 by Robert Stokes
last minute thought

[Nearholmer]

In contradiction to Robert’s advice, which will result in a working system, but can be improved upon very simply, this is what I would do with the bus-wires: make them continuous all the way round.

 

 

Then use a dropper from each rail section to connect to the appropriate bus wire.

 

TBH, having bus-wires, plus the connections provided by the rail joiners, on a circuit this small is really doing a “belt and braces” job, but once you get it right it ought never to let you down, even if you store it in a damp place (it’s usually damp that kills the connection via rail joiners).

 

Very neat carpentry.

 

 

 

[TheGhostofNigelGresley]

Thanks Gents,

 

Robert, that is what I started with, a bus that terminated after the last set of droppers, but a loco that would not cross the gap at either 6 or 12 o'clock, nor work anywhere on the left hand half of the clock. 

 

My second attempt, which is where it is at the moment NH, was to link the bus up into a continuous circle as you suggest. Same difference.

 

So, now that you Gentlemen have been kind enough to validate my thinking, I am reassured to a degree. Obviously I have made a mistake somewhere, but what mistake is possible that would result in a working right hand half only with a continuous bus ?

 

As Sherlock would say ' once you eliminate the impossible, whatever remains, however improbable...'

 

It must be 4 bad solder joints in a row ?

 

I must go to bed also, to be continued....

[Dungrange]

A couple of years ago, a gentleman came along to one of our club meetings.  He had just bought or been given a train set for Christmas, which was basically an oval of track.  Unfortunately, he was under the illusion that it was necessary to have an oval of track for the train to work, so he was rather confused by our end-to-end layouts.  He wanted to know where the power went at the buffer stop and how we had managed to 'complete the circuit'.

 

I had to explain to him that the electrical circuit starts at one of the outputs from the controller, with the electricity flowing along one wire (let's say a black one) to one of the rails (let's say the outside rail).  It then flows through the pickups on one side of the locomotive, through the motor (which turns and makes the locomotive move), through the pickups on the other side of the locomotive to the other rail.  It then flows back to the other output on the controller via another wire (let's say it's a red one).  Thus there is no need for a layout to be a circle or oval (unless you want to run trains round and round in circles). 

 

What is important is that all sections of track are attached to both sides of the controller and that they are wired consistently (ie all droppers and bus wires on the outside rail are 'black' (or whatever colour you have chosen) and all droppers and bus wires on the inside are 'red' (or whatever colour you have chosen) otherwise you would get a short.

 

25 minutes ago, TheGhostofNigelGresley said:

Forget an oval, call it a clock face. The split is between 12 and 6 o'clock. The power enters at 5 o'clock and goes anticlockwise all the way around until 7 o'clock, leaving appropriate slack to allow the fold. Droppers are wired to each piece of track outside and inside rail, rail joiners are used on every joint bar the 'jump' between boards.

 

As you have described it, the layout should work.  When you say the power enters at 5 o'clock, I assume that this means that the output from your controller is connected to the track at this point: two wires, one to each rail.  Between 5 o'clock and 6 o'clock, the rails should be live via the fish plates.  If you have issues here, then it would be a problem with one of the fish plates not connecting properly.

 

I'm also assuming that your bus wires start at the 5 o'clock position, so the path from your controller is effectively along your bus wires with the first connection to the track being at 5 o'clock. 

 

Between 5 o'clock and 12 o'clock, you should have power via either the fish plates or the bus wires.  The bus wires are technically not required, but is good practise because it gives two paths via which the electricity can flow (ie via the fish plates or via the bus wires).  That should make it more reliable.

 

If I'm understanding your issue correctly, you can run a locomotive from the 6 o'clock position to the 12 o'clock position in an anticlockwise direction, but the locomotive will stop at 12 o'clock because there is no power at any point on the other board (ie between 12 o'clock and 6 o'clock if driving in an anticlockwise direction).  That therefore implies that electricity is unable to flow through your bus wires that are connecting the two boards together.

 

A few questions spring to mind:

1. What sort of wire are you using for the bus - a solid core or multi-strand cable?  Multi-strand wire is more flexible and would be all that I would recommend for a folding layout.  If it is a solid core, it's possible that the copper wire inside the plastic sleeve has broken in the folding.  That wouldn't be obvious by inspection, but continuity along the length of each bus wire could be tested with a multimeter.
2. You've asked how the bus finishes, which prompts the question, how have you started it?  The fact that you can drive a locomotive on one board doesn't mean that the bus wires under that board are carrying power, as you could just be relying on the fish plates.  However, if you have droppers at say 5 o'clock, 3 o'clock and 1 o'clock then power should be getting to your bus via some of these connections, even if you do have a poor joint somewhere.
3. When the locomotive stops at 12 o'clock, does it stop because there is no power on the other board (ie you can't drive it from say 11 o'clock to 9 o'clock) or does it stop because there is a short (which would be evident by some sparking when it gets to the join)?  If that were the case, then it would imply that your bus wires cross over, so the wire to the outside rail on the one board is connected to the inside rail on the other and vice versa.

 

1 hour ago, TheGhostofNigelGresley said:

Where it's going wrong is after 7 o'clock, how does the  bus finish ?

 

As you've designed it, the bus is terminated by connecting it to the track at 7 o'clock.  There is, as @Robert Stokes has said, no need for the bus to continue past the last set of droppers and could in fact be the last set of droppers.  However, as @Nearholmer has said, you could also continue these back across the baseboard join to connect 7 o'clock and 5 o'clock.  I could argue that is unnecessary, but it does build in further redundancy because it means that your left baseboard could get power from either the bus connection at 12 o'clock or the one at 6 o'clock, so if one connection is damaged, the layout should still work.

 

However, what confuses me about you post is the 'where it's going wrong is after 7 o'clock'.  What exactly is going wrong at 7 o'clock, since if there is no power on the left board, an anti-clockwise train should stop at 12 o'clock? 

[Dagworth]

Does the loco stop when the first wheel crosses the joint or the last wheel crosses the joint?

 

Andi

[Nearholmer]

This thread is a perfect example of why Doctors should see patients face-to-face, rather than rely on telephone consultations to diagnose their ills.

 

Can we please see a photo of the track on the board? (I guess we all think its 2-rail 00, but it might be something more intesresting)

 

If you start a loco at five o'clock, and go clockwise, where does it stop?

 

If you start a loco at five o'clock, and go anti-clockwise, where does it stop?

 

If you put a loco straddling the six o'clock joint, and turn the controller on, what happens?

 

If you put a loco straddling the twelve o'clock joint, and turn the controller on, what happens?

 

If you put a loco on the track between the two stop points and turn the controller on, what happens?

 

 

[John ks]

Is it possible that bus wires across the gap are crossed over so that the phasing (DCC for polarity of the bus from 6 to 12 o'clock is reversed

 

if a loco will run between between 1 to 5 o'clock & run between 7 to 11o'clock but stops at both joints then the the above is very likely

 

To test for the correct polarity you will need some form of testing device EG a multi-meter or my favourite is a automotive lamp (12Volt, 3 to 12 Watt) The 2 in the photo look to be drawing about 12Watts between them

 

To run these tests you will need the controller to be set to full speed & nothing on the track

 

Tests from A to B , A to b , a to b  & a to B should all light the bulb Or give a reading on a multi-meter set to volts

Tests from A to a & B to b should not light the bulb

 

Hope this helps John

Edited to change some references to DCC Although this applies to DCC

 

 

 

Edited October 28, 2021 by John ks

[Robert Stokes]

I'm back. I think that @Dungrange has covered it very well and the most likely explanation is his number 1, i.e. a broken wire inside the plastic sleeve. If you have used multicore flex for the bus wires then the situation gets even more mysterious.

[TheGhostofNigelGresley]

Morning Gentlemen, (well, it is here)

 

This whole exercise is an experiment. In carpentry, in electrics, in loco maintenance and stock construction and , yes, in re-engaging with the online community too so nice to hear from you all.

 

Loco's stop in their own length when crossing the gaps, it is an entirely bog standard Peco code 100 OO oval I am afraid. It is designed to test loco's and stock and to mindlessly watch trains go round and round, for the time being.

 

So, we can say that the original plan was sound but does not work and the fix was logical but does not work. Therefore, the plan and the fix have not been carried out correctly. Won't be able to examine it until tomorrow, when I will report, 'warts and all', I promise not to spare my blushes for the benefit of those kind enough to contribute...

 

Have a good day/evening,

 

C.

[ikcdab]

I am slightly confused. It would really help of you could post a diagram of how you have wired it.

If you think the wiring is ok, then you need to check the joints. If you are relying on rail joiners for continuity, then beware that they could be loose. If you have soldered wires to the rails, then beware of dry joints..ie joints that look as if they are ok but actually aren't.

[Nearholmer]

I strongly suspect a cross (in fact a double-cross if it is connected as a ring) as the wiring crosses the joints, or a mechanical problem, or that the OP has only installed one bus, for one rail.

 

Let’s wait and see!

[TheGhostofNigelGresley]

Good afternoon folks.

 

It's all very exciting, it now works !

 

I used Scotch blocks to connect the droppers to the bus for the first time - well, it was the first time ever wiring a 'layout' and I couldn't have told you what a scotch block was a few weeks ago.

 

They were also very cheap scotch blocks, which weren't the easiest to work with, I suspect there are much better available. I struggled with them initially, eventually devising a method that worked, but not before damaging the inside bus in two places. Once this section of wiring was replaced, it all worked like it should.

 

So, those who suspected a damaged wire, you were right. Not damaged by the design, damaged by the designer in his haste and uncertainty.

 

So, I now have a 'portable test bed' with continuous running to move forward.

 

Did someone mention kinks :-(

 

Thanks for your help Folks.

 

C.