Charlton Bridge - 4mm BR(S) - Building Bridges

[ikcdab]

While we are on the subject of signalboxes, this is the one for the main termi nus, Charlton Bridge. Scratchbuilt, based on the original at Tulse Hill. Fitted with lighting and a full interior, though it isn't really visible in the picture.

The little brick built building to the left is based on one that used to stand at Eastleigh and is visible in some pics of that station.

 

[ikcdab]

Despite saying I don't like landscaping, I now have the bit between my teeth for this, fuelled by buying a static grass applicator at Warley. Here in this photo I have added card formers and put an initial layer of paper mache over the top. I will then add modroc to firm it up.

It rather looks like a snow scene at the moment, but I am rather pleased with the look of the ballasted track in the foreground.

This is the main double junction (Charlton Bridge Junction) which now runs in a cutting.

 

More to follow.

 

Ian C

Edited November 29, 2022 by ikcdab

[ikcdab]

I have been asked to show some pictures of how my servo and relay configuration works. Its all very conventional.

Firstly, this is a simple diagram of how each point is set up.

 

each point is operated by a switch with two poles. One pole closes the circuit on the servo driver - i use MERG servo4s and these just require the positive terminal for the servo to be connected to the common. This operates the servo. The other pole switches a 12v supply to the miniature relay. This is a SPDT type that switches the polarity. When the 12v is switched on, the relay lies one way, when the 12v is off, the relay drops out and switches the polarity the other way.

 

There are advantages in using the relays over microswitches. Mainly, the relays require no mechanical setting up whereas a microswitch needs to be precisely positioned to be triggered by the servo horn. Secondly, the relay can sit anywhere that is convenient, it doesnt need to be anywhere near the servo. Thirdly, there is no mechanical clicking when the turnout moves.

 

Of course, in practice things are far more complicated than the diagram suggests because a series of turnouts means that the crossing (frog) feed for one turnout is the input for another. 

 

My approach was to build the relays into panels that could then be merely dropped into the circuit. in practice this worked well. I could do all the wiring on the workbench rather than lying upside down under the baseboard. The panels were all made up and tested on the bench before installation.

 

Here is one of these switch panels:

 

 

the miniature relays are at bottom left and in this case, work four turnouts. The terminals labelled A to K are feeds to the track. In the centre is a diode matrix. The terminals on the right are the links for the control panel switches. The terminals on the upper edge labelled 1 to 4 and C etc are signalling feeds. These are linked to the pointwork to give a small degree of interlocking - this is a double junction and the lie of the points dictates which signal arm is activated. 

 

For my main station, Charlton Bridge, things are more complicated, but the same basic principle applies. There are 12 turnouts and these are selected by route setting. The operator turns his rotary switch to (for example) "up main to platform 1" and the diode matrix ensures that the correct relays are triggered. In this case I chose to use DPDT relays - one side of the relay operates the servo, the other side does the polarity switching. I did it this way because I could not get a multiway DPST switch for the panel!

 

 

This panel is laid out just like the previous one. Terminals labelled 11 through 74 are track feeds. Terminals 1 through 12 and C are the servo feeds. The route setting diode matrix is bottom right and the feeds from the rotary switch B to H are the different routes.  So, for example, if the operator selects "Up main to platfiorm 1", then route B is triggered. The feed from route B goes through the diode matrix and therefore energises certain relays that set the servos and switch the polarity. Route A does not exist on the panel as its "everything switched off" - all the points lying normal.

 

just for fun,here are all of the switch panels laid out and ready to be installed.

 

All of this has been up and running now for a couple of years without any problems and with perfect reliability. I have made soem small additons byu way if an extra siding or two and the layout of the panels allowed an easy upgrade route.

 

I suppose it goes without saying that I enjoy wiring and playing with things like diodes and relays etc. I enjoy doing neat work and I love it when it all works OK.

 

Any questions, please ask away..and if anyone wants to visit, then I am very willing to show it all off, I am in Somerset. Just PM me.

Ian

 

 

[St Enodoc]

10 hours ago, ikcdab said:

I have been asked to show some pictures of how my servo and relay configuration works. Its all very conventional.

Firstly, this is a simple diagram of how each point is set up.

 

each point is operated by a switch with two poles. One pole closes the circuit on the servo driver - i use MERG servo4s and these just require the positive terminal for the servo to be connected to the common. This operates the servo. The other pole switches a 12v supply to the miniature relay. This is a SPDT type that switches the polarity. When the 12v is switched on, the relay lies one way, when the 12v is off, the relay drops out and switches the polarity the other way.

This might be a stupid question but why not switch the frogs direct from the DPDT switch and eliminate the relay (and its power supply) altogether?

[ikcdab]

1 hour ago, St Enodoc said:

This might be a stupid question but why not switch the frogs direct from the DPDT switch and eliminate the relay (and its power supply) altogether?

It's a very good question!  If I was just switching a single turnout then that would be fine. But I have mostly gone for route setting operated by rotary switches.  I found it difficult to find suitable (and affordable) dpdt equivalents so opted for keeping the switching simple.  Also, the wiring would have been complex behind my control panel.  I just found it simpler to build the separate switch/relay panels that (in effect) plugged into the back of my control panel.  Keeping it modular like this kept things simpler and reduced the bird's-nest of wiring. 

In a few cases I have one off turnouts that in the prototype might have been operated by a hand lever by the side of the track.  In this case I did indeed do as you suggest.

I also liked the idea of using relays and using dpdt relays also meant I could integrate a very simple degree of signal interlocking.  Eg a signal won't clear unless the route is set for it.

Very good question though!

Ian

[Ighten]

Lovely work Ian, will be looking forward to following this.

[St Enodoc]

17 minutes ago, ikcdab said:

It's a very good question!  If I was just switching a single turnout then that would be fine. But I have mostly gone for route setting operated by rotary switches.  I found it difficult to find suitable (and affordable) dpdt equivalents so opted for keeping the switching simple.  Also, the wiring would have been complex behind my control panel.  I just found it simpler to build the separate switch/relay panels that (in effect) plugged into the back of my control panel.  Keeping it modular like this kept things simpler and reduced the bird's-nest of wiring. 

In a few cases I have one off turnouts that in the prototype might have been operated by a hand lever by the side of the track.  In this case I did indeed do as you suggest.

I also liked the idea of using relays and using dpdt relays also meant I could integrate a very simple degree of signal interlocking.  Eg a signal won't clear unless the route is set for it.

Very good question though!

Ian

Ah, I get that, especially the bit about DPDT relays - in your earlier post you implied that they were SPDT, hence my question!

[ikcdab]

1 hour ago, St Enodoc said:

Ah, I get that, especially the bit about DPDT relays - in your earlier post you implied that they were SPDT, hence my question!

Yes.  I have a mix of both depending on the situation!

[ikcdab]

So I have been doing some ballasting.  I'm pleased with this outcome.  Just a lot more to do.

[GWR57xx]

Just stumbled across your thread.

Fabulous project, very nicely done.

I’ve learned a lot reading through to this point, thanks for sharing.

 

 

[ikcdab]

20 minutes ago, GWR57xx said:

Just stumbled across your thread.

Fabulous project, very nicely done.

I’ve learned a lot reading through to this point, thanks for sharing.

 

 

Hi GWR, many thanks. I am just working on a level crossing and 3d printing servo mounts.....watch this space...

[ikcdab]

My general approach is to be a butterfly and I normally have several projects on the go at once, and i flit between them all.  My attention today has been on the level crossing.  

Here is the general view of the crossing as it currently stands and the signalbox:

 

I intend that each of the four gates will be driven by a servo, all linked (conveniently) to a MERG servo4 module. I have 3d printed servo mounts and made some little connecting pieces that go onto the servo "hub" and screw onto the rod projecting down from the gate post. The flat piece with the two tubes sits on top of the baseboard, the tubes passing through. One tube takes the gate pivot and the other tube accommodates the gate post peg.

 

 

The gates are the MSE cast whitemetal kit. In another thread i agonised over how to fix the netting on. But I am pleased with the overall look of them.

 

Here are a pair of gates ready for fitting:

 

As to operating them. I have opted to have a separate control desk for the gates adjacent to the crossing. This is a pretty simple affair, but I am rather pleased with the sign. I have found a good online plastic sign engraving company where you can get such signs engraved for very little. 

I have not yet installed any kind of interlocking and for now will rely on red and green LEDs.  I will have to do something though to prevent run throughs

 

I have just started installing the gates will post more later.

 

One question though. The gates need the full 90 degree turn of the servo. the first one is OK, but I have just added the second servo and this is only giving me about 85 degrees "lock to lock". Using the MERG board and the sema4 software to programme it, I have specified the full 90, but one servo isn't doing it. Is this down to individual servos  - they are all the same type?

 

Ian

[ikcdab]

So finally its all setup and working. I had to change out a servo that couldn't manage 90 degrees. Little bit of tweeking in the MERG servosetplus software and we are off. I have programmed in some bounce so that the gates appear to bang against the stops and bounce back....let me know what you think..

 

Ian

 

Edited January 28, 2023 by ikcdab

[TrevorP1]

I like it! That's a really nice job all round, including the signal box itself. The electronics are way beyond me!

 

Just one small constructive observation. Is is possible to make the gates moves bit slower? I only say this because in reality there would be a poor signalman winding a handwheel round. 

[ISW]

25 minutes ago, ikcdab said:

let me know what you think..

Ian,

 

That's simply brilliant. Simple and well thought out. I suppose you 'could' have done it with a single servo and some 'complicated' linkages, but I'd have gone down your 4-servo route as well. Much easier.

 

Are you going to add some red lights to the gates?

 

Ian

[ikcdab]

33 minutes ago, TrevorP1 said:

I like it! That's a really nice job all round, including the signal box itself. The electronics are way beyond me!

 

Just one small constructive observation. Is is possible to make the gates moves bit slower? I only say this because in reality there would be a poor signalman winding a handwheel round. 

Thanks for the reply. I use the MERG servo4 boards and drive them with the MERG servosetplus software. I have the speed on the slowest it will go! Thats the penalty for driving the gates directly from the servo. If I had an indirect drive (i considered using spur gears) then I could have geared it down a bit more. But I found I had too much backlash in the gear train and the gates didn't stop accurately. So I opted for the direct drive and slightly faster. For more than 30 years I was a signalman on the WSR and I swung the gates at Blue Anchor on very many occasions. They could go like that if the wind was blowing hard! The other advantage is that come the day when I have a train barreling down onto a crossing with gates  not yet open, I might just get them open in time to avoid too much destruction!

 

20 minutes ago, ISW said:

Ian,

 

That's simply brilliant. Simple and well thought out. I suppose you 'could' have done it with a single servo and some 'complicated' linkages, but I'd have gone down your 4-servo route as well. Much easier.

 

Are you going to add some red lights to the gates?

 

Ian

 

Hi Ian,  thanks. It is convenient that MERG do the servo4 boards and that servos are very cheap. The adjustments to get accurate motion with one servo and linkages sound fearsome.

 

Red lights: may be. I used the MSE kit which does come with some fairly amorphous pieces to represent lights. I didn't put them on because some photos of the prototype didn't have them and I didn't like the castings.  But I now think that having the red lamps might add a bit of colour and I might add them on. But I want to get the road and wicket gates done first.

 

Ian

[TrevorP1]

22 hours ago, ikcdab said:

I was a signalman on the WSR and I swung the gates at Blue Anchor on very many occasions. They could go like that if the wind was blowing hard! The other advantage is that come the day when I have a train barreling down onto a crossing with gates  not yet open, I might just get them open in time to avoid too much destruction!

 

 

I must have watched you in action then! I used to visit the WSR a lot when I lived in Hampshire - one of my favourite preserved lines. Too far away now for a day trip but we're staying in Dunster in June so the WSR is top of the list.

[jamest]

Hi Ian,

 

Those gates look great, it really adds another dimension to the layout. I am not very experienced with the electrical side of things but I am thinking of joining merg to learn a bit more. I have a few fellow modellers in the Barnstaple area who are members and are way ahead of me on such things. It would be good to explore options for other movements on the layout and general use of servos.

 

You mention the WSR….my neice’s boyfriend does a lot there I think….Phil Sizer…he is an actual signalman as a day job now. But I’m sure there are several people volunteering there.

 

Cheers,

James

[ikcdab]

41 minutes ago, jamest said:

Hi Ian,

 

Those gates look great, it really adds another dimension to the layout. I am not very experienced with the electrical side of things but I am thinking of joining merg to learn a bit more. I have a few fellow modellers in the Barnstaple area who are members and are way ahead of me on such things. It would be good to explore options for other movements on the layout and general use of servos.

 

You mention the WSR….my neice’s boyfriend does a lot there I think….Phil Sizer…he is an actual signalman as a day job now. But I’m sure there are several people volunteering there.

 

Cheers,

James

Hi James, thanks, I'll PM you.

Ian

[BetweenTheTunnels]

Hi Ian,

Thanks for the comment over on my new 3mm thread. I've just spent an enjoyable hour or so reading back through your thread.  Well done on replacing some of the images after the rmWeb crash.  The layout is looking really good, you should be proud of what you have achieved!

 

Im a MERG member too - plan is CBUS and Servo drivers for points on my layout ... but im a bit away from that at the moment!  However, very impressed with your handywork on the track. I've done a little bit in the past, but not much so a learning curve coming there.

 

Now following along with interest!

Richie

[ikcdab]

22 hours ago, BetweenTheTunnels said:

Hi Ian,

Thanks for the comment over on my new 3mm thread. I've just spent an enjoyable hour or so reading back through your thread.  Well done on replacing some of the images after the rmWeb crash.  The layout is looking really good, you should be proud of what you have achieved!

 

Im a MERG member too - plan is CBUS and Servo drivers for points on my layout ... but im a bit away from that at the moment!  However, very impressed with your handywork on the track. I've done a little bit in the past, but not much so a learning curve coming there.

 

Now following along with interest!

Richie

Thanks for the comments. I've been distracted onto other things this week, but I need to get back to the layout soon!

Ian

[ikcdab]

I have been working on signalling. Although it's not finished, I am rather pleased with this LSWR co-acting home signal. 

Powered by servos from a MERG servo4 board. I just noticed that a balance weight has dropped off.... Oh hum.

Ian 

https://youtube.com/shorts/Iriiertg8Z0?feature=share

 

 

 

[ikcdab]

About time i did some updating on this. But in the meantime, I am planning an additional siding at the harbour station. No real reason other than I like building track and wiring it!

The diagram below shows the new track in red. 

 

 

It is intentional that the portion to the left of the crossover is shorter than the right - its limited by the location of the harbour walls.

My quandry (on which I would like comments) is whether the new crossover should be facing (shown in red) or trailing (shown in green).

The advantage of the facing (red) option is that incoming trains can run directly into the new siding without needing the loop to be clear. The disadvantage is that because the track to the left is shorter, it limits how many wagons can be accommodated. 

If i use the green crossover,  a train must first run into the loop, then propel over the crossover into the long siding. 

For me, the wiring will be more straightforward with the facing (red) option, it will just be another notch on the rotary switch that currently allows you to select any of the exisiting roads.

I guess there are pros and cons both ways, but any suggestions will be gratefuly received!

Full update later.

Ian

 

[Enterprisingwestern]

1 hour ago, ikcdab said:

About time i did some updating on this. But in the meantime, I am planning an additional siding at the harbour station. No real reason other than I like building track and wiring it!

The diagram below shows the new track in red. 

 

 

It is intentional that the portion to the left of the crossover is shorter than the right - its limited by the location of the harbour walls.

My quandry (on which I would like comments) is whether the new crossover should be facing (shown in red) or trailing (shown in green).

The advantage of the facing (red) option is that incoming trains can run directly into the new siding without needing the loop to be clear. The disadvantage is that because the track to the left is shorter, it limits how many wagons can be accommodated. 

If i use the green crossover,  a train must first run into the loop, then propel over the crossover into the long siding. 

For me, the wiring will be more straightforward with the facing (red) option, it will just be another notch on the rotary switch that currently allows you to select any of the exisiting roads.

I guess there are pros and cons both ways, but any suggestions will be gratefuly received!

Full update later.

Ian

 

 

Depends if you want to add some operational interest, personally I'd go green, can't beat a bit of shunting!

 

Mike.

[ikcdab]

Time goes by so fast.   Anyway,  moving on from above I have decided to access the new siding with a facing connection.

Templot to the rescue, I loaded up my layout plan and added in the new trackwork.  I have gone for a spacing of 65mm from the adjacent running line.  Printed out the relevant pages and stuck to piece of ply.

As the intention is for this track to be inlaid, I have gone with copperclad construction. I also like soldering very much indeed.

Here are some shots of progress so far:

 

 

I tend to cut the gaps in the sleepers with a shallow half round file so that I get tapered edges.  Once painted,  the gaps disappear.

The great thing about templot @martin_wynne is that I can get fantastic gentle curves. This crossover is on a very large radius, must be about 20m, and running into a transition curve.

All the other techniques are as per normal copper clad construction. 

Further pictures later!

Ian