2mmFS Long Melford

[justin1985]

Thanks Ian, sorry I scanned to the bottom of the thread and read Don's post, but hadn't noticed yours when first replying. 

 

Thanks for the explanation of the risks associated with shorts. I was half aware of this, so your more detailed explanation is appreciated. Is the 5A booster you're referring to the MERG one? I guess I should work on the basis that any future booster is likely to be at least 5A. So 32/0.2 wire would be a sensible minimum for the bus, if not mains cable (still feel like I'd prefer the flexibility of multi-strand ...)

 

Thanks for the pointer to the pluggable terminal connectors. I did have in mind something akin to a heavier duty version of the old computer Molex connector, but didn't know what to search for! It looks like the female sides of the connectors are only available as PCB mount, and don't have any additional means of fixing besides the solder joint. Do you find that they are robust enough? 

 

J

[Ian Morgan]

The Merg booster can be built for either 5 amp or 10 amp output. From a quick google, it appears the NCE PowerPro is 5 amp, while the NCE PowerCab is 2 amp and the DigiTrax Zephyr Extra is 3 amp. Variety is the spice of life.

 

Merg also do a kit for a District Cutout (DCO), that can be built to cut out at either 1.5 amp or 3 amp. If you divide your layout into separate 'districts' (e.g. up line and down line, or main line and goods yard) you can connect 2 or 3 DCOs to the output of your DCC system or booster, and then connect the output of each DCO to the track of its district. This also gives the advantage that a short on one district will not stop trains moving in the other districts.

[nick_bastable]

 

 

Thanks for the pointer to the pluggable terminal connectors. I did have in mind something akin to a heavier duty version of the old computer Molex connector, but didn't know what to search for! It looks like the female sides of the connectors are only available as PCB mount, and don't have any additional means of fixing besides the solder joint. Do you find that they are robust enough? 

 

J

 

If your worried make a a few spares and link to the boards via chocblocks    or just use chocblocks !

 

Nick

[Caley Jim]

On Kirkallanmuir I've used these, which are rated at 6amp.  The female halves are screwed to the underside of the baseboard and the male halves are on double ended links between the two boards with the wires bound together with spiral cable tidy.  There are therefor no trailing cables when the layout is dismantled.

 

Jim

Jim

[Nigelcliffe]

Thanks Ian, sorry I scanned to the bottom of the thread and read Don's post, but hadn't noticed yours when first replying. 

 

Thanks for the explanation of the risks associated with shorts. I was half aware of this, so your more detailed explanation is appreciated. Is the 5A booster you're referring to the MERG one? I guess I should work on the basis that any future booster is likely to be at least 5A. So 32/0.2 wire would be a sensible minimum for the bus, if not mains cable (still feel like I'd prefer the flexibility of multi-strand ...)

 

 

Its very sensible to do the core wiring on the basis of 5A.  

 

But, when it comes to a 2mm layout, you don't need 5A, and should be using less around the layout, and certainly don't get anything any larger than 5A.   

Its far more more sensible to have lower currents kicking around small scale layouts.   

Manage the current either with power district breakers set to low currents or to use a number of low current boosters for different layout sections.   

The MERG DCO Ian mentions can be built to be 0.75A or 1.5A which makes it very good for 2mm scale (rather than the "official 1.5A or 3A"), something which I discovered when testing the pre-production version - wind the fat wire through the sensing coil twice (it goes, though a tight fit), and the sensitivity is halved.    Only possible thing against the MERG DCO is that it is incompatible with RailCom.   That only matters if you have a use for RailCom on the layout. 

 

 

 

Back of envelope calculation:   my locos draw between 50mA and 150mA.   At 50mA, that's 100 locos running together on a 5A system.  Even at 150mA its over 30 locos moving simultaneously.    

 

 

 

- Nigel

[CF MRC]

It all sounds pretty dangerous to me....

 

Tim

[Caley Jim]

It all sounds pretty dangerous to me....

Which?  5amps of current or 100 locos all moving at once?   

My use of the terminal block plugs had nothing to do with their current rating, just that they were cheap and cheerful and easy to wire up, thus complying with my KISS principle.

 

Jim

[Donw]

Many thanks for the advice. I just picked up some 24/0.2 from Maplin that is (suposedly) rated for 6A (the equivalent from Rapid etc seems to be 4.5A, so I suspect Maplin have been optimistic ...). I have got some mains cable sat around, but I don't really fancy wrestling solid core cable through the rather constrained space under the layout unless its absolutely necessary. 

 

The booster for the Roco DCC system I've got has a rating of 3.5A, so either way that should be within tolerance. I'm certainly not planning to run any solenoids or point motors from the same power bus. The point motors and uncouplers that are already on the layout are wired entirely separately, and I'll probably stick to that set up for the foreseeable future. I can't imagine ever having more than two or three locos 'live' at any one time on this layout, so current draw under normal circumstances shouldn't be a problem - mainly concerned about shorts etc? 

 

On the basis of Don's comments, I would have thought it would be OK to use the 24/0.2 for the bus, and the 16/0.2 for droppers and shorter runs to tag strips etc. 

 

Would it be acceptable practice to stick with the D-SUB connectors between boards, but double up the bus connections? 

 

Justin

 

I tend to use the plug in terminal strips they are available in various ratings 5A is fine they are quite robust. However if you have a lot of wires for point motors etc they can be bulky perhaps just use for the DCC bus.

 

Andy Peters used a couple to supply power to a lift out section and found they were good enough to hold the section in alignment power and track alignment in one.

 

I am puzzled that you can have a short  not quite enough to cause a shut down with out noticing any problems. If the wiring and the connections are giving a resistance of 3 or 4 ohms I would have thought it would show up as a voltage drop  unless the resistance is just the short itself in which case the wiring should be well capable of carrying a suitable current. Ian's mention of doing a test of putting a short on at the furthest point to check the DCC will shut down is a good one. Also I would advise anyone to get into the habit of turning the layout power off whenever leaving the room it might be just a cup of tea then the phone goes or the doorbell. Anything left on can be an issue if you are not there to spot a problem.

 

 

Don

Edited January 29, 2018 by Donw

[justin1985]

Many thanks for all of the help and advice, much appreciated!

 

A few more hours work this evening has got all of the tracks in the scenic section rewired to a simple set of red/black feeds, using the 24/0.2 wire.

 

I'll get hold of some 32/0.2 for the main power bus and connections to the other boards. I actually found some of the plug-in choc-block type connectors in my electrical bits box, so I'll use those for the power bus connection between boards, and just keep the D-SUB connections for analogue point control, accessories etc.

 

I've kept the beginning of the siding running towards the bridge switched separately as a manual isolating section. Nonetheless, I've still stripped out an awful lot of cable and switches. It all bells through as intended on a continuity test with no shorts.

 

However, the vee section of one of the two turnouts doesn't seem to have any continuity with its microswitch. As the trackwork is tidied up and painted, it's very difficult to try and trace back where the connection is even meant to be on the top of the layout - it's very well disguised! I guess I'll have to take the paint off in that area and try and find it, or just drill through a new feed, maybe?

 

I still need to tackle the hidden return tracks. Each of the rails is fed from no less than four feeds! AND it's linked end to end with additional wires underneath (Over a distance of only 75cm). I think a feed to each end of these tracks on this board, from a central bus, should be absolutely fine

 

J

Edited January 30, 2018 by justin1985

[Nigelcliffe]

I am puzzled that you can have a short  not quite enough to cause a shut down with out noticing any problems. If the wiring and the connections are giving a resistance of 3 or 4 ohms I would have thought it would show up as a voltage drop  unless the resistance is just the short itself in which case the wiring should be well capable of carrying a suitable current. Ian's mention of doing a test of putting a short on at the furthest point to check the DCC will shut down is a good one.

Back of envelope sums again:

 

Assume a 5A system, running at 15V to track, total resistance of wiring (out and back) to achieve a short circuit shut-down must be  R=V/I  = 15/5 = 3ohms.  Lets assume some sub-standard wiring achieving a 5ohm total wiring resistance. 

Loco drawing 200mA (a lot in 2mm scale), effective resistance at 15V is R=15/0.2 = 75ohms.   

 

So, from "front of layout near command station", where the resistance might be zero, to the "back of layout where sub-standard wiring of 5ohms is installed", the total resistance of the loco plus wiring varies from 75ohm to 80ohm.  So, the track voltage seen by the decoder will drop from 15V to 14V.  If the layout had a sequence of power droppers installed from front to back,  I doubt most would notice such a small gradual change in loco speed. 

 

But, if fitted with a 1.5A power cutout, and the loco derails at the back, and there's a bit of resistance through the pickups (an over-the top 1ohm), then the total resistance is 5ohms of wiring, 1ohm of pickup, total 6ohms, at 15V, which gives 2.5A of current, and the 1.5A cut-out trips to protect things.   

[nick_bastable]

Back of envelope sums again:

 

Assume a 5A system, running at 15V to track, total resistance of wiring (out and back) to achieve a short circuit shut-down must be  R=V/I  = 15/5 = 3ohms.  Lets assume some sub-standard wiring achieving a 5ohm total wiring resistance. 

Loco drawing 200mA (a lot in 2mm scale), effective resistance at 15V is R=15/0.2 = 75ohms.   

 

So, from "front of layout near command station", where the resistance might be zero, to the "back of layout where sub-standard wiring of 5ohms is installed", the total resistance of the loco plus wiring varies from 75ohm to 80ohm.  So, the track voltage seen by the decoder will drop from 15V to 14V.  If the layout had a sequence of power droppers installed from front to back,  I doubt most would notice such a small gradual change in loco speed. 

 

But, if fitted with a 1.5A power cutout, and the loco derails at the back, and there's a bit of resistance through the pickups (an over-the top 1ohm), then the total resistance is 5ohms of wiring, 1ohm of pickup, total 6ohms, at 15V, which gives 2.5A of current, and the 1.5A cut-out trips to protect things.   

gosh double maths in the morning thought I was back in short trousers again

 

however a clear and very educational post

 

thanks

 

Nick

[Crosland]

I am puzzled that you can have a short  not quite enough to cause a shut down with out noticing any problems. If the wiring and the connections are giving a resistance of 3 or 4 ohms I would have thought it would show up as a voltage drop  unless the resistance is just the short itself in which case the wiring should be well capable of carrying a suitable current.

 

Being pedantic, if the voltage is all in the "short" then it is not a short, it's an overload. It's an important distinction between faults (shorts) and overloads that any electrician will recognise.

 

No, it's not so critical with fast acting cutouts used with DCC but it's still a useful distinction.

 

Old style fuses and breakers react faster as the current increases but will allow a considerable overload current  to persist for a long time, with possibly disastrous consequences. A fault (a real short) will always cause an immediate trip if the wiring is up to spec.

[Donw]

Being pedantic, if the voltage is all in the "short" then it is not a short, it's an overload. It's an important distinction between faults (shorts) and overloads that any electrician will recognise.

 

No, it's not so critical with fast acting cutouts used with DCC but it's still a useful distinction.

 

Old style fuses and breakers react faster as the current increases but will allow a considerable overload current  to persist for a long time, with possibly disastrous consequences. A fault (a real short) will always cause an immediate trip if the wiring is up to spec.

 

Well there is the fact that it is a 'short' with enough resistance to limit the current. I am an electrical engineer and at one time was involved in designing domestic fans and part of the job was to ensure that should the fan jam the device would not burst into flames. That is what I would define as an overload where the device is drawing more current than intended. A short is where the current finds an alternative path instead of through the device it is intended to supply. In the case of a layout unless the wiring is way undersized there should be a low enough resistance that shorting the rails out at any point will trip the safety in the command module. However it was postulated that with a combination of bad joints and poor contacts it could limit the short circuit current to below the trip value. To me this suggests serious faults in the wiring. 

If you consider the case where a loco stalls and draws a higher current that would be an overload if higher than the decoder could manage. It would probably destroy the motor before it tripped the command module. The trip in the command module is there to protect the module from being overloaded whether by a fault or too many devices drawing current.

 

Don

[justin1985]

Many thanks for all of the help and suggestions on wiring for DCC. I've now finished re-wiring the little crossover board for DCC/one engine in steam DC. I imagined this would just one or at most two evenings work - in the end it probably took about 4 or 5 evenings. The cold weather in the last week or so meant that I wasn't keen to spend more than an hour or two at a time in the garage though! It might be integral to the house, so theoretically gains heat from the rest of the house, and the door to the outside is now insulated with plenty of Celotex, but it isn't heated at all. It might never get real extremes of temperature, but it isn't entirely welcoming when its freezing outside! 

 

I went with a scheme of using 32/0.2 wire for the "bus" and from the controller sockets, 24/0.2 for most wiring within the board, and 16/0.2 for the feeds to the wire droppers. There are one or two droppers of even thinner wire left where they are basically impossible to get to to change without major surgery. But those are generally feeding only very short stretches of track, or are not the only feed to that length of track.

 

My new wiring is not a patch on the neatness of Bill's, but at least I understand it now!

 

 

I've temporarily fixed the bit of tag strip that is acting as the hub of the bus onto one of the bits of pine stripwood that forms the basis of the landscaping, but I'll move this onto the Tufnol board that houses the rest of the electronics once I'm happy with the interboard connections. I've got some of the pluggable choc-block type connectors to use as the bus connections, and will leave the 15-pin D-SUB connectors to deal with the accessory feeds and the one or two switched section feeds that run across the board joints. 

 

 

Once it was all wired up below, I turned my attention to belling through the track to test the connections. It turned out that the front turnout of the crossover didn't have any feed to its straight stock rail, as the tiny bit of brass wire acting as a "fishplate" from the end section of track, which had the feed, had a dry solder joint. I fixed this, but might also think about adding an additional feed at the other end of the stock rail as insurance.

 

More puzzling to solve was the fact that the crossing of that front turnout wasn't getting a feed, despite it all being nicely soldered from a microswitch underneath. It turned out that the microswitch common was actually soldered to a dropper in the wrong location. I added a hole alongside one of the sleepers and soldered on a 0.4mm brass wire folded and filed to sit reasonably flat on top of the sleeper. Not as neat as it might have been, but I didn't fancy drilling through a sleeper and the thick ply its firmly stuck to directly, when everything else is in place.

 

Testing with my J94 and some short wheelbase wagons revealed a few tight spots in that front turnout, but it was easy to ease out one knuckle of the crossing, which was a bit tight, and also one checkrail, which got tighter at one end. All runs beautifully now! Just only for about two feet, so far ...

 

 

I find it interesting that Bill built these turnouts with pivoted, rather than flexing, switch rails. I'm guessing it was probably for reasons of durability? 

 

Next job will be to wire up the bridge board, which has the droppers attached but not wired in yet, but it is nice and simple - just two hidden through lines, one scenic through line, and a single siding. Hopefully I should be able to get trains running from the crossovers through to the train table within another week or so!

 

J

[Lacathedrale]

I'm chuffed to see this progressing - good luck with the bridge board! 

[Donw]

Many thanks for all of the help and suggestions on wiring for DCC. I've now finished re-wiring the little crossover board for DCC/one engine in steam DC. I imagined this would just one or at most two evenings work - in the end it probably took about 4 or 5 evenings. The cold weather in the last week or so meant that I wasn't keen to spend more than an hour or two at a time in the garage though! It might be integral to the house, so theoretically gains heat from the rest of the house, and the door to the outside is now insulated with plenty of Celotex, but it isn't heated at all. It might never get real extremes of temperature, but it isn't entirely welcoming when its freezing outside! 

 

I went with a scheme of using 32/0.2 wire for the "bus" and from the controller sockets, 24/0.2 for most wiring within the board, and 16/0.2 for the feeds to the wire droppers. There are one or two droppers of even thinner wire left where they are basically impossible to get to to change without major surgery. But those are generally feeding only very short stretches of track, or are not the only feed to that length of track.

 

My new wiring is not a patch on the neatness of Bill's, but at least I understand it now!

 

IMG_20180208_221550.jpg

 

I've temporarily fixed the bit of tag strip that is acting as the hub of the bus onto one of the bits of pine stripwood that forms the basis of the landscaping, but I'll move this onto the Tufnol board that houses the rest of the electronics once I'm happy with the interboard connections. I've got some of the pluggable choc-block type connectors to use as the bus connections, and will leave the 15-pin D-SUB connectors to deal with the accessory feeds and the one or two switched section feeds that run across the board joints. 

 

IMG_20180208_221558.jpg

 

Once it was all wired up below, I turned my attention to belling through the track to test the connections. It turned out that the front turnout of the crossover didn't have any feed to its straight stock rail, as the tiny bit of brass wire acting as a "fishplate" from the end section of track, which had the feed, had a dry solder joint. I fixed this, but might also think about adding an additional feed at the other end of the stock rail as insurance.

 

More puzzling to solve was the fact that the crossing of that front turnout wasn't getting a feed, despite it all being nicely soldered from a microswitch underneath. It turned out that the microswitch common was actually soldered to a dropper in the wrong location. I added a hole alongside one of the sleepers and soldered on a 0.4mm brass wire folded and filed to sit reasonably flat on top of the sleeper. Not as neat as it might have been, but I didn't fancy drilling through a sleeper and the thick ply its firmly stuck to directly, when everything else is in place.

 

Testing with my J94 and some short wheelbase wagons revealed a few tight spots in that front turnout, but it was easy to ease out one knuckle of the crossing, which was a bit tight, and also one checkrail, which got tighter at one end. All runs beautifully now! Just only for about two feet, so far ...

 

IMG_20180208_221853.jpg

 

I find it interesting that Bill built these turnouts with pivoted, rather than flexing, switch rails. I'm guessing it was probably for reasons of durability? 

 

Next job will be to wire up the bridge board, which has the droppers attached but not wired in yet, but it is nice and simple - just two hidden through lines, one scenic through line, and a single siding. Hopefully I should be able to get trains running from the crossovers through to the train table within another week or so!

 

J

 

I suspect Bill was replicating the older heel switches where the blades were jointed at the heel giving flexibility.

 

Don

[Caley Jim]

I suspect Bill was replicating the older heel switches where the blades were jointed at the heel giving flexibility.

 

Don

Loose heel switches have a totally different look to flexible ones. In the open position the former are straight and lie almost parallel to the stock rail, whereas the latter curve away from it at the tip.

 

Jim

[justin1985]

I had planned to tackle the wiring on the bridge board next, but looking more closely, it makes sense to finalise the wiring on the train table fiddle yard board first, as the connections are made on the bridge board. 

 

There is currently a bank of three SPDT switches, with colour coded collars, on the back of the bridge board, which aren't connected to anything at all yet. Just next to this, the fiddle yard board has a 9-pin D-SUB connector wired with a pair of red and black wires for each of the three lines that join the fiddle yard. Presumably Bill intended the three switches would isolate each of the lines on bridge board. This would also serve to protect the approaches to the train table.

 

 

However, if I'm running as DCC, there is obviously less need for isolating sections on the mainline and the two return tracks. The major advantage that I can see of being able isolate these sections is to prevent accidentally running a train onto the train table when it isn't aligned. 

 

The train table itself is fed through a series of large "micro"switches, so it is only fed from the track that it is aligned with, when it is locked and aligned. The feeds from the next board each connect to the microswitch, and the approach tracks are fed off the same tab - so Bill must have intended to be part of the section from the bridge board. 

 

(Incidentally I haven't been able to find these large switches online, probably because I don't know what you'd call them. The only one I saw that looked the same was listed as a dishwasher spare!) Does anyone know what they're called?

 

 

However I wonder whether a better solution, at least in a DCC scenario, would be to wire the approach tracks on the fiddle yard board to the switched side of the microswitches, so the approach tracks on this board are only live when the train table is aligned and locked in place. As far as I can see it, this would protect against accidentally running onto the train table when not aligned, and allow me to feed the board with just a simple DCC bus feed.

 

Does this sound like a reasonable plan?

[Donw]

Loose heel switches have a totally different look to flexible ones. In the open position the former are straight and lie almost parallel to the stock rail, whereas the latter curve away from it at the tip.

 

Jim

 

That's what I thought Bill was trying to replicate. Because we would find it difficult to have a working fishplate it would be necessary to provide a pivot which is not prototypical but has a very similar effect.

 

Don 

[Lacathedrale]

Justin, if you're going with DCC there's really no reason why the whole train table can't always be live without this extremely complicated wiring, is there? This isn't a case where an errant voltage is going to slowly edge your stock off the precipice! 

Edited February 13, 2018 by Lacathedrale

[Donw]

I see no problems with what you have planned.  You could simplify the wiring but even if you want to have the whole traintable  live so you still need to have some means of changing the polarity when the table is reversed and a mechanism for feeding it without wires getting twisted round. Typical solutions

 

Using bolts connected to the supply tracks which hold the table and carry the current . Brass rod and tubes are basically home made bolts

Using contacts which connected to the table these can be for individual tracks or two arcs to connect to either end

Using slip rings (or an audio jack plug as the pivot) to connect through and an auto-reverse unit which precludes using DC

Using small audio jacks one either end with a plug on a wander lead.

 

On a club layout I have made the connection to the entry exit track and the main layout through a bias switch so power is only applied when the operator holds the switch over. This means that someone at the other end cannot suddenly apply power while the fiddle yard operator is not looking. Using an On-Off-On switch you can choose between local or main power supply if using DC. If on DCC it can avoid problems with selecting the wrong loco on a controller. This is designed for exhibition use where any club member can be 'press ganged' into operating. But is worth considering if you plan to exhibit or regularly operate the layout with others. 

 

Don

[justin1985]

My current understanding is that the train table itself is fed via its pivot from the blue and white wires seen at the bottom of the picture, which are daisy chained to all of the large "micro" switches. The actual tracks, however, are only fed and activated via the ring of small micro switches under both sets of rail ends, which are activated by the locking bolt.

 

Therefore, I think (although I haven't tested exhaustively), when voltage is applied to the tracks on the table, it is only when that track is aligned, AND is never reversed relative to the approach track.

 

Hopefully I've understood that correctly!

 

I can't help thinking it would be a good idea to protect the approach tracks because of the kinds of silly errors I can imagine making as an operator. At an exhibition this layout would definitely need at least two operators, allowing one to keep an eye on the return tracks and fiddle yard the same time. But at home, if the back scene is on, it's impossible to see both the scenic and return sections at the same time. So I can fully imagine loosing track of a train on the return tracks when distracted.

 

It might not be possible to send a train into the abyss, but it would be possible to drive it against the table when there isn't a track aligned, and derail (presumably risking a short). The geometry of the table doesn't allow more than one track to be aligned at any one time.

 

Therefore if the approach tracks were isolated/switched with the table's feed, there would be no risk of a forgotten about train derailing.

 

Of course, I might still be over complicating things!

 

J

Edited February 13, 2018 by justin1985

[Donw]

My current understanding is that the train table itself is fed via its pivot from the blue and white wires seen at the bottom of the picture, which are daisy chained to all of the large "micro" switches. The actual tracks, however, are only fed and activated via the ring of small micro switches under both sets of rail ends, which are activated by the locking bolt.

 

Therefore, I think (although I haven't tested exhaustively), when voltage is applied to the tracks on the table, it is only when that track is aligned, AND is never reversed relative to the approach track.

 

Hopefully I've understood that correctly!

 

I can't help thinking it would be a good idea to protect the approach tracks because of the kinds of silly errors I can imagine making as an operator. At an exhibition this layout would definitely need at least two operators, allowing one to keep an eye on the return tracks and fiddle yard the same time. But at home, if the back scene is on, it's impossible to see both the scenic and return sections at the same time. So I can fully imagine loosing track of a train on the return tracks when distracted.

 

It might not be possible to send a train into the abyss, but it would be possible to drive it against the table when there isn't a track aligned, and derail (presumably risking a short). The geometry of the table doesn't allow more than one track to be aligned at any one time.

 

Therefore if the approach tracks were isolated/switched with the table's feed, there would be no risk of a forgotten about train derailing.

 

Of course, I might still be over complicating things!

 

J

 

I dont think so Justin. It is very easy to do something wrong when the public are asking you questions at an exhibition.

 

Don

[justin1985]

I finished the wiring on the bridge and fiddle yard boards last night, although it isn't quite ready to test run yet. I realised that my idea of moving the feed for the train table approach tracks to the microswitch that feeds the table would resulted in them all being live whenever any one track was aligned, which defeated the point. The large switches only had a single set of poles so I'd need to add change or add extra microswitches to make it work that way. Maybe another time.

 

I feel a bit bad that my wiring is no way as neat or well planned as Bill's. But at least I understand it.

 

 

So for now the fiddle yard is wired using the bank of switches at the end of the bridge board. After I'd wired them I noticed that they only latch in the "down" direction, not "up". I'd wired "up" as "on", but this is actually quite handy in terms of protecting against mistaken trips off the track, so I'll leave it. The slight mistake was forgetting that, being a semicircle, the polarity of the return tracks is (obviously) reversed compared to the front! So I'll have to swap the wires, probably at the above board switches, because that's the most accessible point. Now the boards have been humped back into place on their trestles, I'll dig out an extension lead to take the soldering iron to the board, rather than lumping it back to the bench.

 

So, the moment when a train can run (only out and back) is pretty close! The lack of wiring on the bridge board seems to suggest that nothing had actually run before now, so it feels like a pretty momentous occasion! Somehow the choice of working 2mm locos that I have doesn't really seem sufficiently grand ...

[justin1985]

 

Here we go, it all works now! 

 

To be honest this wasn't the very first run - it took quite a few runs, starting with the bo-bo diesel, to work out which bits of track were still dirty after an initial clean. About 15 mins of strategic track rubber-ing, its running pretty smoothly. Some of the board joints are causing little judders, but I think that is because the floor isn't level and I haven't yet adjusted the trestles. There are still one or two other niggles, like the fact that the D-SUB cables are so heavy\stiff that they won't hang in the connectors of their own accord. Bill had fixed the sockets with normal screws, but it will need the threaded nuts as used on computers for the cables to screw on to. 

 

So now, I'm now facing the bigger question of how exactly I develop the other boards as discussed earlier in the thread. I'll probably just end up concentrating on building more stock for a while ... 

 

Justin