Brimsdown-The last grand project.

[trustytrev]

Hello,
Is it possible to get a diamond cutting disk for longer life with these machines?
trustytrev.

[Philip Hall]

A diamond disc is available and I have one to try one day. I was recommended to try this ‘special steel‘ blade by the supplier and it has been pretty good. It may be that the diamond disc gives a slightly cleaner cut but as this works well still I’m not going to make a change until the blade is completely worn out. It’s easy to change but a bit of a fiddle in a small space.

I don’t know whether a diamond blade will last longer (yet!) If it’s of interest I can photograph the two blades.

Philip

[Terry Bendall]

The only problem is that it doesn’t go all the way to the table bed when cutting such a thin strip,

That is probably the best that can be done Philip and as long as the teeth are covered that should be sufficient protection. The normal practice with larger saws is that the guard, known as the crown guard, is "as close as is practicable" to the top surface of the material being cut. In practice about 10mm or a a bit less on the basis that your fingers are thicker than 10mm.

I use thick coffee stirrers to push the PCB though and against the fence as well as to hold down it down as the bits get smaller.

An ideal solution and correct practice.

Terry Bendall

[Tony Wilkins]

After concentrating on getting the relay cards done, because they were simpler, (relatively speaking) I have now gone back to the display cards, however what should have been relatively straight forward, has turned into something of a saga. One of the last pictures I posted was this one.

The strip-board on the right was the last one I then had (since used) so ordered some more. When the order arrived, including other components I had ordered, the strip-boards turned out to be the wrong size, only half as long (like those in the middle) and of little use to me. After checking I discovered that the the wrong item had been put to stock by the supplier so needed to be returned for a refund. This presented a conundrum. If I reordered, there was a good chance of a repeat performance, or did I wait and hope they would sort their stock out first? The problem was that I had reached a stage where I couldn't make further progress without more strip-board.
I decided to try an alternate supplier I sometimes use and found a suitable, but longer, alternative. These were ordered and duly arrived the next day.
I was therefore able to make the next display card.

There are a lot more components on this one that the first one shown above.
There are other differences. The top PCB has the display modules as part of the build (for testing purposes, it will need to be separated later anyway) whereas for the latter ones I made them separately, this is where the last piece of strip-board went.
Despite doing this, the resulting PCB is still longer than the one above after shortening it, meaning that I would not have been able to fit everything needed onto the PCBs I originally ordered, so it is perhaps serendipitous that I ended up with the longer ones. I only hope none of the other two display cards are any longer as I have reached the maximum length I can sensibly fit across the width of the control panel.

At the top is a full length piece of strip-board. At this length it is a bit unwieldy for wiring, but not knowing the required length, I left as is until I had finalised the component layout.
The new card at the bottom has its display PCB to the right.
The plan is to link them with some pieces of flat flexi cable that I have on order, the problem here is they are currently out of stock and not due in till mid November. Until then I cannot link the two together and test them out. I am loath to do so temporarily as strip-board does not take kindly to repeated soldering and unsoldering of components, so I will just have to bide my time. It aint as though there aren't other things to get on with in the meantime.
Regards
Tony.

[Tony Wilkins]

Well all the PCBs are now done and here is the full set (minus display boards) laid out in the base of the control panel.
This may not be the final arrangement as fixings for the front panel have yet to be finalised.

Some weeks back I ordered the Aluminium sheet I would need for the front panels. I finally got round to opening the package yesterday. The supplier specified their cutting tolerances as +2 -0mm, so I reduced my specified width of the side pieces by 1mm just in case. The sheets are all cut to -0mm so I have two small gaps to live with now. Perhaps I should have just gone for the sizes I wanted in the first place, but I didn't want to be faced with lots of filing in order to get things to fit. There is going to be enough of that to do anyway with the display cutouts etc.

Tony.

[Tony Wilkins]

So here is the first fit of the main aluminium front plates (ignoring the trial fit which showed some minor adjustments were required).
The rather attractive blue colour is the protective plastic film as supplied.

After some debate I decided to hinge the front plate for access. This in itself created some issues with fitting and alignment.
It has meant repositioning some of the circuit boards. The wooden blocks will give additional support for the panel when down.

The paper printout gives a good impression of the intended appearance of this part of the control panel.

The angled panel at the back will house the numerical LED displays for the roads selected. The next job will be to cut the holes to mount these as they need to line up accurately with the display driver PCBs to be mounted on the base. The back plate will have to be removed for this.

Tony.

[Tony Wilkins]

Well here is the back plate with the holes cut and three of the numerical LED modules fitted. The forth one is still attached to the rest of the display driver board and I am a bit loath to detach it at the moment as the connecting cables I have on order are currently unavailable for another month or so.

[Tony Wilkins]

Well I finally took the plunge and printed the panel on my Vinyl sheets with mixed success. It was every bit as trying as I thought it might be. Due to the extra thickness over paper, it has a tendency to jam in the mechanism. This was the second attempt. This is actually two sheets of A3 joined together on the backing paper with sellotape.

I used this to position and mark the placement of all the required holes in the front panel. To prevent it moving during the process, I used two strips of masking tape at either end to hold it in place. This did not turn out to be one of my better ideas as when I later attempted to remove the masking tape from the film it left sticky residues behind, which rather negated the reason for using masking tape in the first place. Attempts to remove this with various solvents failed but did succeed in smearing some of the printed ink thus ruining the vinyl printout. Attempts to print off another were of varying quality, but I eventually managed to produce two halves that were, I hoped, usable.
However, I pressed on and drilled all the holes that I had by now marked with a center punch.
I thought I had taken a picture of the plate with all the holes drilled, but it was not in the camera.
Choosing the best two vinyl sheets I then attempted to stick these onto the surface of the front panel correctly aligned. I don't know what the best technique for using large self adhesive vinyl sheets is, but I clearly didn't have it. The result isn't what I would have hoped for but I decided to live with it, at least for the moment. When I had the Aluminium sheets cut, I ordered two of everything just in case, so I do have a second front plate spare.
I then spent a happy evening fitting all the switches and this is the result.
It's beginning to come together and is going to be quite impressive. At least, I think so.

The underside looks like so.

There is going to be a lot of wiring required. One thing I made sure of was that all the push button switches were the same way round as this means the same tags are wired up on each switch, so this only has to be tested once with a meter.

Meanwhile, when assembling the storage yard baseboards post wiring, I discovered that some of the baseboard joints needed attention and one in particular was a real doorstep. I separated the baseboards to investigate and this is what I discovered.

The bottom of the Sundeala board had de-laminated and is not the first time this has happened during this construction. Sundeala ain't what it used to be and I have had second thoughts about making that choice in the light of experience, however, there is no going back now. After cleaning out the split with a thin saw blade, as much wood glue as possible was inserted with the aid of a spatula. the area was then firmly clamped and left to set overnight.

The result?
The rail direction of the step was less but reversed. This was dealt with by raising the rail ends on extra solder.
Regards
Tony.

[triumph3]

Having visited Tony ( socially distanced) on Friday I was very impressed with the scale of the layout that he is building. It’s one thing to see a track plan, but to see it in the flesh makes you realise how big it is. The layout is larger than most clubs or groups would attempt to build, so Tony deserves huge credit for the progress to date.

David

[Tony Wilkins]

Whilst waiting for the flexi cables to arrive, I had intended to get on with some other jobs pending. Things didn't quite work out that way, but I made good use of the time in other ways. My main computer has been acting up for a while now and has recently taken to crashing randomly. Investigation pointed to a faulty memory module and a replacement was sought. Due to the age of the machine new parts weren't an option, but an online search proved fruitful and one was ordered and when installed I am glad to say cured the problem. Until this was done, I was loath to alter files and save them in case they became corrupted, or worse.

The cables finally turned up a few days earlier than predicted, so after finishing the current job, I was able to get back to some wiring.
The flexi cables were soldered to the LED module PCBs and in turn connected to their driver board via header socket strip for testing.

All four LED modules could then be installed in the rear panel and the jumper cables can be seen hanging down below the panel.
The wired connector was the temporary lash up to test the first display board. This will have to be disconnected and done properly.

The next job was to wire the connectors for the driver boards ready for installation. Here is the first one to be done.
The three single colour wires Grey, Black and White are power rails and the multi colour wires are matched to those on their respective tags, at least in theory.

[Tony Wilkins]

I say in theory because the probability of errors always exists.

I cut 8 pieces of strip board for the edge connectors, but owing to two of the display cards being longer than expected, I was forced to mount these edge connectors vertical instead of horizontal as intended and some angle mounting brackets were fabricated. The height then becomes an issue as there are switches mounted on the front panel above and I had to reduce the height by two rows of holes. However I did not discover this until after I had wired the first edge connector. So off came the wires and out came the saw. Then it had to be rewired. It was not until I wired this in that I discovered I had used a White / Orange wire instead of an Orange /White wire as can be seen on Tag 52. Annoying, but I will live with it.
The other Display card edge connectors were wired up in turn. The central extra tag strip is for power supply distribution.

Next come the Relay cards.

Unlike the display cards that only have inputs, the Relay cards have both inputs and outputs.
The outputs go to the Tag strips, but the inputs go to the front panel, which since I wanted the ability to work on as a separate item, means further connectors. My options are limited, but a solution has been devised and parts ordered.
Regards
Tony.

[Tony Wilkins]

My connectors arrived later that afternoon and were soon soldered into place.

Saturday was spent wiring the relay card connectors to the tag strips.
Here is the first one done.

By 11pm all were in place.

This just leaves the front panel to wire and fit, then a thorough testing session will commence to find the faults.
Regards
Tony.

[Dave Holt]

Tony,
It all looks quite mind boggling to me.
Hope it all works with not too many faults to resolve.
Dave.

[DougN]

Seriously impressed Tony. My next layout i want to be as tidy as your control board above! Avoiding all the flying leads and so on. Your tag strip across the bottom is an idea that I had through about and I think I will adopt!

[Tony Wilkins]

Tony,
It all looks quite mind boggling to me.
Hope it all works with not too many faults to resolve.
Dave.

Hi Dave.
I will be pleasantly suprised if there are no errors in something this complex, especially as I have not been able to fully test some of the sub modules before final assembly.
I have been following your Royal Scot thread where it is my turn to have my mind boggled! Your attention to detail is something else and you have my greatest respect.
Regards
Tony.

[Tony Wilkins]

Seriously impressed Tony. My next layout i want to be as tidy as your control board above! Avoiding all the flying leads and so on. Your tag strip across the bottom is an idea that I had through about and I think I will adopt!

Hi Doug.
Using tag strips is a good discipline I think. They encourage documentation of the connections, a typical example attached

Yard Up 1.DOC

(16 KiB) Downloaded 59 times

and they can be a great aid when fault finding as there is something to hook the meter onto.
Most of the layouts I have been involved with were done this way. Yes, it is more work, but I think it more than worthwhile.

Regards
Tony.

[Tony Wilkins]

Not a lot of progress to report since the last post I'm afraid, things like Christmas (such as we can have this year) keep getting in the way.
Anyway, Shortly after my last post I realised that I had missed two switches off, not only the front panel, but the schematic diagram as well. These are for the Ponders End and Enfield Lock Distant signals, which are physically mounted on some of the Brimsdown signal posts and need to be operable. So the holes have been drilled and switches installed but with no labeling for the moment.
The other decision to make was how to keep the front panel removable. Since I need two 50 way cables to give myself enough wires, I decided to reuse some that I already had. The relay cards alone need 46 ways so these were allocated to one cable (leaving 4 spare) as there will be connectors at the relay card end. The other cable would need to have a connector somewhere in the middle. After some thought I decided to see if I could reuse the existing connectors as this would save an appreciable amount of work. The only reason I have these is that I rescued them from the scrap bin and there is a reason they were in there. The connectors are 50 way Amphenols with IDC contacts. Now for the uninitiated IDC stands for Insulation Displacement Connection and the wire is forced into a slot in the contact that cuts through the insulation and makes contact with the internal core. Over time with movement this type of contact can become loose and intermittent and then the cable has to be replaced. Thus the cables integrity needed to be tested with a multi meter. I discovered one conductor that was intermittent, but by pushing the wire firmly into the contact continuity was restored.
It was then a case of deciding how to mount the socket half in the control box. I found some suitable mounting pillars, but the hole through the center was too small for the wood screws I had chosen. I then discovered that they would not go through the holes in the connector either. On a whim I tried the screws that I had taken out of the connector in the pillar as this was already threaded and to my amazement they fitted. I then chose an unopened bag of countersunk machine screws I had to hand and found they were the same thread too, serendipity! Such moments happen very rarely, but when they do it's almost magical. I therefore marked and drilled two suitably sized holes though the plywood case and countersunk the outside before mounting the connector thus. The cable is anchored with a suitable size P clip screwed to the deck.

Complete with other half, the cable of which will be fixed to the underside of front panel via self adhesive pads and cable ties.

Note the blue film rubbed off the rear panel. This was caused by the back edge of the front panel rubbing against it when lifted. I have removed about 1mm from the back of the rear panel support blocks to hopefully cure this.
Regards
Tony.

[Terry Bendall]

Such moments happen very rarely, but when they do it's almost magical.

It is. My best jobs are when I have everything in stock and don't have to buy anything.

Terry Bendall

[Tony Wilkins]

With Christmas and New year now behind us, time for some more progress with the layout and the control panel in particular.
There were still some small display PCBs to make such as these.

The odd shape of the main one is dictated by where it has to go.

The small PCB fits here. The self adhesive mounting pillars are some I have had for at least 40 years and they still stick as tenaciously as ever.

It was at this point that I could no longer put off starting the remaining wiring and this has taken about 5 days work.
This is the front panel with the first 50 way cable wired in. This cable supplies the power to front panel via the tag strip left of center.

Likewise the second 50 way cable.

This situation was achieved at about 11PM Wednesday and I couldn't resist fitting the front panel to the base and powering up everything bar the 8 relay and display PCB's before retiring for the night. This however confirmed my pessimistic prediction as several things did not work as expected, but at least no fuses blew!

The following day was spent with a test meter trying to figure out what was going on and some of the readings I was getting were not what I would have expected. One of the displays mysteriously refused to work, so I decided to try the one I knew did and that worked, so I then knew my basic design was sound and any fault lay elsewhere. I then tried the relay card that partnered the working display. Dead as a Dodo. The meter revealed that a return wire was open circuit, which was traced to a dry solder joint. Not altogether surprising as that colour wire (Orange) was very old and the ends of the pre-cut lengths had oxidised quite badly. Despite my efforts to clean the wire ends before use, one had not taken.
What I then discovered was that although the relays selecting each road energised on pressing their switch, they did not drop out when another road was selected meaning multiple roads could be selected concurrently although they could be reset by pressing the default road switch. Consulting the diagrams I realised that I had overlooked an alternative electrical return path through adjacent relay contacts. Extra diodes would be required to cure that problem. A further problem that I suspected may occur was due to bounce with the switch contacts causing intermittent multiple triggering of the relay reset circuit, which was especially a problem when the contact breaks. This effectively cancelling any road just selected. A bit of extra capacitance in the right place has cured that one and I now have a set of relay and display cards working reliably. Having got one pair working I know I can get the other three to do the same.
So here is the current situation.

The display on the right should show 0, but does not show anything until at least road 5 is selected and then works correctly for all higher road numbers.

This display also displays 8 for both road 6 and 8, so that needs sorting.
Unfortunately some of the faults require under baseboard access to fix so they can wait for now.
I have every confidence now that I will get there, but it may take several days.
Regards
Tony.

[Andrew Bluett-Duncan]

Hello Tony

To say that I'm impressed would be an enormous understatement. Indeed I'm not sure what impresses me more, your knowledge of electronics and ability to design this control system, or your obvious ability to sort out the bugs that inevitably come with such an undertaking, or is it your ability to talk about everything in a clear and understandable manner that a complete novice (like me ) can understand. Or actually, the speed and accuracy with which you work.

I think I'll plum for the ability to sort out the technical hitches along the way.

Anyway, Tony the tenacity, expertise and graft that you apply to the whole thing is highly impressive, not to mention the end product.

Kind regards
Andrew

[Terry Bendall]

Very nice Tony, but that is what we have come to expect by now.

your knowledge of electronics and ability to design this control system, or your obvious ability to sort out the bugs that inevitably come with such an undertaking,

I thing it is both, in fairly equal parts. Both come from many years of experience but anyone can gain that sort of knowledge and understanding with a suitable degree of effort - and the time.

ability to talk about everything in a clear and understandable manner

One of the qualities of a good teacher.

Terry Bendall

[Andrew Bluett-Duncan]

Very nice Tony, but that is what we have come to expect by now.

your knowledge of electronics and ability to design this control system, or your obvious ability to sort out the bugs that inevitably come with such an undertaking,

I think it is both, in fairly equal parts. Both come from many years of experience but anyone can gain that sort of knowledge and understanding with a suitable degree of effort - and the time.

ability to talk about everything in a clear and understandable manner

One of the qualities of a good teacher.

Terry Bendall

Hello Terry
When you say ...

"I think it is both, in fairly equal parts. Both come from many years of experience but anyone can gain that sort of knowledge and understanding with a suitable degree of effort - and the time."

I think when you conclude that time is a factor in this, my feeling is that yes given, in my case vast amounts of time, then I suppose that I might be able to achieve this level of knowledge. But realistically in my case, it would take so long for something that I possess little or no aptitude for, that I don't feel I'd ever be able to get there. On the other hand, I'm absolutely with you in your remark about the qualities of a good teacher.

Kind regards
Andrew

[Terry Bendall]

I think when you conclude that time is a factor in this, my feeling is that yes given, in my case vast amounts of time, then I suppose that I might be able to achieve this level of knowledge. But realistically in my case, it would take so long for something that I possess little or no aptitude for, that I don't feel I'd ever be able to get there

Yes it can take time Andrew, especially to get to the higher levels of understanding and that applies to any area of knowledge. I developed an interest in electronics through my teaching career starting in about 1980. It has been said that the best way to understand a topic is to have to teach it and that I what I did. The same sort of thing can apply to something like using a lathe.

No one needs to develop the high level of electronics knowledge that Tony has in order to be successful in their railway modelling and these days DCC makes things a lot easier. I think that everyone needs to decide how they are going to do things be it baseboards, track building, locos and stock and gradually build up the skills they think they will need. Some may have friends who can do things for them, or show them how and work alongside. Some will be able to afford to pay someone else to do the work. Others may not have those options or may choose to work at things until they reach the skill lever they are satisfied with. I think we all have to accept that there are some things that we may have limited aptitude for and find ways of working around that.

A project I am working on at the moment would ideally need a painted backscene with a 3D element. I don't have those sort of skills so when it comes to that part I may have to try and develop them or buy a photographic backscene. I shall see when I get there but in the mean time there are lots of other things to do.

Apologies for hijacking Tony's thread.

Terry Bendall

[Tony Wilkins]

Hi Terry and Andrew.
Thanks for the compliments.
I do perhaps have an unfair advantage in that I worked in the electronics game for a large part of my career, but my entry into this was not what would today be considered conventional. I developed my knowledge largely as a hobby and interest. In my first job as a lab technician I solved an electrical conundrum that one of our works governors said was impossible. I just saw it as a challenge. That got me noticed and when a vacancy came up in the electronics design section it was offered to me. I then learned a lot more on the job and the ability to read and understand data sheets furthered my knowledge.
In my second job I stayed after work to help one of my colleagues who was struggling to get a microprocessor design working as part of his college project. Again reading the data sheets provided the solution. I remember, not very long after I had joined the company, one particular circuit assembly job where I was one of the favoured few being asked to come in over the weekend and help assemble a large batch of PCBs that were urgently needed for the Monday. I was given my first batch to assemble, which I worked my way through. When, on completion, I returned them, I was told to slow down a bit as they had booked the Sunday as well for the job, which they didn't want to miss out on as it was double time. Those were the days. I was quite chuffed to be informed that all my boards had passed the test stage. I spent part of Sunday afternoon sorting out the few failures.

My approach to the control side of this layout may be considered a step backwards in as much as there is less electronics employed than on my previous layout Green Street. This was a deliberate policy driven by the rapid change in the world of electronics. Many of the electronic devices I intended to use on Green Streets' control system became obsolete many years ago and I therefore chose to use a standard relay type (BT47) which has already been around for a good many years and is likely to be around for a good many more. In some ways they are also easier to understand.

Thus far I have corrected several faults. The right hand display board is proving something more of a challenge. I have found and corrected two faults, but curing the second one has introduce further problems as a couple of things that previously worked now display incorrectly. I have worked out why, but solving the issue will require some design mods. A side issue is that updating the documentation to reflect the physical changes takes as long as the actual work.
Regards
Tony.

[Tony Wilkins]

Just to update the previous post. I have now discovered one of the reasons why I was having so much trouble getting this display board to work correctly. On checking my original logic chart, I have made error in the logic list, which explains a lot. I have now corrected this situation and altered the display board to suit. This has cured one of the outstanding problems, however in the process of modifying things yesterday, I inadvertently introduced a further error by bridging the wrong track with solder causing an 8 to be displayed for road 8 and upwards. This has now been corrected and I am pleased to say this one is now working correctly.
I have also found and corrected an assembly error with the left display board but there are still two more faults to rectify on this as neither road 1 or 5 displays when selected.
Regards
Tony.