Sarum Bridge

Post details of your T gauge layouts and the progress you are making.
Jmyrick
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Re: Sarum Bridge

Post by Jmyrick »

NICE!

martink
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Re: Sarum Bridge

Post by martink »

The level crossing is now working. Four el-cheapo $3.00 servos controlled by a dedicated computer equivalent to the new Peco Smart Switch. The gates are clear plastic with the framework scribed on by a screwdriver, painted white then wiped clean. A bit rough, but easily replaced in the future.

A quick video... http://youtu.be/nD_m1co-QWg


The circuit board and ultra-sophisticated mountings for the servos...
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The business end being tested with pieces of sticky tape instead of gates. This gets pushed up through 4 holes in the baseboard, then the real gates are super glued into position....
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The first attempt at proper gates. As usual with T, they look better at a distance.
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mattd10
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Re: Sarum Bridge

Post by mattd10 »

Wow! That level crossing is absolutely fantastic!
Are you going to include them in the automation so they open when no trains are coming?

Sent from mobile device

martink
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Re: Sarum Bridge

Post by martink »

mattd10 wrote:Are you going to include them in the automation so they open when no trains are coming?
Yep. Already done. The crossing is on the quietest spot on the line, behind the viaduct. It isn't as visible there as I would have liked, but that is the only place where the trains are far enough apart to give it time to open and close again.

Ozrail
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Re: Sarum Bridge

Post by Ozrail »

That Level crossing is super impressive.
Don't worry about it being in place you would like, think of it as a layout easter egg.
Most layouts have something people ovelook, but a few do notice, even on mine.
Check out my Shapeways store for T-gauge stuff.
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http://www.shapeways.com/shops/everythingtgauge?s=0

martink
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Re: Sarum Bridge

Post by martink »

That's finally the end of this batch of changes. No more work on the layout for a couple of months. And this time I really mean it. Really! Well, except for another couple of locos... And some fixes to the speed control logic... And some more buildings ...

So, here's a slightly-more-polished-than-my-usual video of the whole kit and kaboodle...

http://youtu.be/dfCoFVD2H_U

mattd10
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Re: Sarum Bridge

Post by mattd10 »

WOW! I could sit and watch that all day! The automation is fantastic, changing signals, level crossing...all such great little extras! You don't see details like that on larger scale layouts, let alone in T!

I love the HST whizzing over the viaduct and the mix of trains! The speed changes seem a lot more noticeable with the HST (maybe something to do with the way it was filmed, or the fact it has 3 power cars whereas the freights don't?) but still looks absolutely amazing!

Cannot wait to see it finished and at an exhibition one day!

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tjejojyj
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Re: Sarum Bridge

Post by tjejojyj »

I agree although I'm not sure I could watch it ALL day. (I have looked at it three times & I didn't notice the subtitles the first two times as I was so absorbed in the action and the details even as they stand.)
On one of the early shots the freight train crossing the bridge seems to be noticeably surging. Is that right? And is that just a byproduct of the PWM controller?

martink
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Re: Sarum Bridge

Post by martink »

Glad you both like the video - it was fun to make and gave the layout its first really good workout. It added up to at least two hours of running, and after some initial problems with wagon couplers, swapping coaches around a bit on the HST, etc., it all ran remarkably well. I consider this a (successful) dry run for a possible exhibition showing later this year.

I haven't tracked down the cause(s) of the speed fluctuations yet. I think I might still have a software problem here, and there also seems to be a hardware one with the controllers. I believe that one is tied up with the overload protection part of the circuit - all the power feeds through a current sense resistor, so as trains (particularly the HST with its three motors and lights) are switched on to and off from that controller the output voltage will vary for the other trains running on that unit. I can see a couple of possible remedies, but I'll leave that for the next stage. I should also be able to reliably run the trains much more slowly when I get around to double-heading all the trains with the locos wired together to give them 4-bogie pickup. Anyway, all of the issues look manageable.

I didn't think to get any shots of what happens when the level crossing didn't trigger properly or one time when my sleeve tripped the cancel sensor prematurely and the gates closed on a goods train passing through! These were the usual minor hiccups that only show up when you run something for real.

BTW, you might not have noticed the subtitles at first because I only added them a couple of hours after initially posting the video on youtube.

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tjejojyj
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Re: Sarum Bridge

Post by tjejojyj »

I'm glad to hear the sub-titles were added later (I didn't think I was that unobservant). They are a nice touch.

You many know of this already but my only suggestion on the video would be to put more light on the layout when filming. Your camera should "stop-down" in response and give better depth of field. (Personally I wouldn't mind some closeups of the signal going to green and a train departing. :) )

martink
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Re: Sarum Bridge

Post by martink »

I am afraid my camera skills are sorely lacking (though hopefully improving). I did use as much extra light as I had at hand (three desk lamps perched on chairs or clamped to a bookcase), but we had a dull and cloudy weekend down here in Melbourne so my preferred natural light option wasn't available. It will be easier to film when I get around to adding proper layout lighting.

I tried to make the signal shots as interesting as possible, but they don't show up all that well in the video. For example, the two home signals protecting the platforms are three aspect and quite busy in the shot, but their yellow state is barely detectable by the camera. I use a multiplexed driver chip to power them so yellow is actually rapidly alternating green and red flashes which works well for the human eye, but the camera shows this a slightly flickering reddish-orange. I can see them changing in the video, but I doubt most viewers would notice.

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tjejojyj
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Re: Sarum Bridge

Post by tjejojyj »

I thought the framing and editing of the video were fine and sometimes you need a camera that has a lot of manual settings to get the final "10%" of polish.
(It always helps to have a compelling and interesting subject!)
Hopefully I'll be in Melbourne when your displaying it.

martink
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Re: Sarum Bridge

Post by martink »

It looks like Sarum Bridge will be making its debut appearance at this year's Caulfield (Melbourne) exhibition in August, one of the larger shows down here in Oz, so I've pulled it out of the cupboard and got back to work on it. Ah well, the best laid plans of mice...

I have completely reworked the speed control electronics, replacing the 3 555-based PWMs (one per speed notch) with 4 PIC-based units (one per section). These are all fully synchronised and driven by the one PIC to avoid speed surges when crossing section boundaries, and have basic inertia for smooth starts and stops. They are pretty much a drop-in replacement for the earlier bank - I just added a couple of extra plugs to bypass the old speed control relays and redirected a few other cables. It all behaves much better now.

I have also picked up a couple of new 16M motorised chassis, so over the next few days will be updating the two loco-hauled trains to be double-headed (adding a class 25 and a motorised siphon). With any luck, that should completely resolve the last lingering speed issues.

martink
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Re: Sarum Bridge

Post by martink »

The permanently coupled and wired double-headed approach seems to work out well. Here is a quick video of a basic creep and start/stop test. The wheels and track are not particularly clean, and some of the locos were stuttering along and needing a helping hand when running individually. This is using my original test track and the standard Eishindo PWM controller.

http://youtu.be/7BAgmvBZjas

martink
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Re: Sarum Bridge

Post by martink »

I am back working on the layout after a fair old break. This might have something to do with it being scheduled for its first public showing at this year's exhibition at Caulfield (Melbourne, Australia) in just over a week, one of our larger shows downunder. I'll try to post some pics and a new video of it in its completed (!) state after the exhibition, but here are a few work-in-progress shots.

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The final form of the wiring. Most of that big circuit board on the left is now redundant and disconnected - I ended up replacing its controllers and speed-switching relays with a second board with a micro handling four synchronised PWM controllers, one per track section. It all works much better now - the trains speed up and slow down properly. I really should have done it this way to begin with and saved a lot of time and effort. The signals and level crossing controller are clearly visible.

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The layout in its current state, buried beneath heaps of grass scatter while waiting for the glue to dry. Tomorrow I'll pick the layout up, turn it upside down, and give it a good shake to see how it all turned out.

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The full set of buildings - still pretty rough and ready, but less so than the previous mockup version. Customised printed images wrapped around balsa formers, with Plastruct L-girders for roofs and short lengths of styrene strip for chimneys. The concrete footbridge is built from a length of Plastruct U-girder.

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dkightley
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Re: Sarum Bridge

Post by dkightley »

There's nothing like a pending show to focus the mind! ;) ;)

Your layout is looking really, really good.....and I look forward to seeing more pictures and video!

Good luck with the final preparations....and for the show.
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

martink
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Re: Sarum Bridge

Post by martink »

Getting there at last - the station is finally starting to look like a station. Really just road vehicles, people and touch-ups still to go... ... and maybe some station nameboards and a new backscene.

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martink
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Re: Sarum Bridge

Post by martink »

Here are a couple of shots of the final pre-exhibition scenic updates...

The vehicles and people really, really help. I tried using the Eishindo people, but they are just vaguely humanoid plastic blobs. I ended up using the pre-painted, etched brass (2D!) 1:400 people from a Czech company called Eduard (they do accessories for model ships and aircraft). Their 1:450 ship's railings also make good fences - you can cut them out as 2-, 3- or 4- rail types as needed.

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dkightley
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Re: Sarum Bridge

Post by dkightley »

This is stunning!!

The little people and the vehicles bring the layout to life!


Looks as if I'll have to investigate this supplier.......


btw. Are the platform lights simply flat headed nails??? If they are, they look perfect!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

martink
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Re: Sarum Bridge

Post by martink »

I was very pleasantly surprised by the standard of the Eduard figures (http://www.eduard.com/store/Eduard/Phot ... 1-400.html). BTW, the drawing on the linked page is accurate - that is exactly how they look. They are flat (which requires some care in placement for reasonable viewing angles) and a bit too vivid (a thin wash of light grey paint over the fret fixed that). I found that the easiest way to stick them in place was to leave the fretwork tabs on their feet, then bend these over with tweezers to make a stand. Bending the figures to put them on seats was also trivially simple.

The station lights are just Peco track pins.

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