Working Signals

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martink
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Working Signals

Post by martink »

As one of half a dozen simultaneous projects, I have been looking at adding working colour light signals to Sarum Bridge. The initial tests are looking good, so now all I have to do is make the signals look like real signals.

The signals are made from short lengths of optical fibre aimed at multi-colour LEDs beneath the baseboard to give fully functional three-colour searchlight signals. The length of fibre is pretty much the entire signal - both the mast and the head. The end of the fibre is bent over sharply to form the lens and hood. The current versions are still rough trial pieces - they need straightening, and I have some tiny 0.8mm washers on order for the back backplate. I will post again when they are complete.

I would have liked to go for dummy multiple-aspect signals with a dummy head wrapped around the single searchlight aspect, but that is beyond my current capabilities. Perhaps one of you 3D types might consider it? Searchlight signals were uncommon in the UK, but the GWR used them on a small scale between the wars. These were exact replacements for semaphore types, so fit in well with the automation I am also working on.

The red aspects are a lot redder than they appear in this video (camera issues):
http://youtu.be/IbVGsgC5lBw

Note the brass tube leading the fibre to the LED on the left.
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Ozrail
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Re: Working Signals

Post by Ozrail »

Very impressive work. :D
Check out my Shapeways store for T-gauge stuff.
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http://www.shapeways.com/shops/everythingtgauge?s=0

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dkightley
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Re: Working Signals

Post by dkightley »

I think we're all going to have to include something in each photograph we post that gives an indication of how small things are.

The second photo looks at first glance as if enormous brass tubes and thick plastic rod has been used...until you realise that the tails of the screws through the baseboard seem a bit too big in comparison! :shock: :shock: ;) The true scale of things then becomes obvious...that those plastic rods are in fact fibres.
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

mattd10
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Re: Working Signals

Post by mattd10 »

These look great! I tried to get a 3D print of signals to hold a fibre optic cable, but the small diameters meant the tubes were all bunged up in the printing process so were completely unusable. My next attempt was going to be very similar to what you're doing...using the fibre optic itself as the signal and paint it black or something, but this never got off the drawing board for me!

martink
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Re: Working Signals

Post by martink »

I will be sticking with the searchlight signals, but what I was originally thinking of for a 3D multi-aspect head was something like this, with a slot in the back and a hole for one aspect. Bend and insert the fibre, then seal it with glue. And don't even think about ladders.

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jerrybigcat
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Re: Working Signals

Post by jerrybigcat »

Gold Medal M<odels has brass ladder stock in 1/400 and 1/500 scale. :)

martink
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Re: Working Signals

Post by martink »

Now that the heavy scenic work is done, I got around to finishing these off. A length of optic fiber, bent 90 degrees at the top, a 1mm washer slipped over the end, a dab of PVA glue to hold the washer in place and form a back-shell to the signal head, and a quick coat of paint. As usual, they look a lot better at a distance. There are 11 of them on the layout.

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tjejojyj
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Re: Working Signals

Post by tjejojyj »

Gee that's impressive. I have to remind myself how small they are. Once the ground cover and ballast goes in it will be "scary good", as they say, when seen in person. (I like the boom gates too.)
I wonder if you had more depth-of-field on the photos whether it would make it look even better?

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dkightley
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Re: Working Signals

Post by dkightley »

Here's a YouTube video showing how two aspect signals for N gauge can be made:




I'm sure the technique can be used to make T signals...I particularly like the use of the plastic "skin" from paper clips as uprights.
Doug Kightley
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martink
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Re: Working Signals

Post by martink »

dkightley wrote:I'm sure the technique can be used to make T signals...I particularly like the use of the plastic "skin" from paper clips as uprights.
I have more than a few doubts about this one. I have used similar techniques (making and kitbashing products from CR Signals) for my still unfinished N gauge layout, and I found that wiring and handling the LEDs at this size was about at my limit of skill.

Please note these pics are in N, and the signal heads are still slightly overscale, and since T is 1/3rd of that...

If you do make the attempt, I would be really, really interested in the results.

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mattd10
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Re: Working Signals

Post by mattd10 »

It looks like a pretty fiddly job, but I had also never heard of wire glue so may try and track some down!

A quick ebay search brings up some RGB three colour 0603 LED's (ever so slightly bigger than the 0402) which may be useful for making searchlight signals. The alternative is to buy the SMD's pre soldered to wires. The disadvantage here is there is no way of knowing the thickness of wire used.

I've got yet another plan in the pipeline so may have a play with these when the time comes!

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Nutter
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Re: Working Signals

Post by Nutter »

Experimenting with a similar idea in Z scale , but not got very far yet. Have to sort out the exact design but should be able to do 3 aspect powered from the 10v ac output on a Marklin transformer. Or a 9v battery.
Mike
DON'T knock it at least I am trying to do something, with only one good hand.

mattd10
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Re: Working Signals

Post by mattd10 »

So I decided to order some 0402 SMD LED's from ebay on a whim (£3.50 for a pack of 50, can't go wrong) and they've just arrived. It's very much a T gauge moment where I knew they'd be small, but these are something else. They are insanely small! There is no way I could ever solder these so I'll wait for my wire glue to arrive from china and then have a play! (as a side note I ordered a load of yellow ones as an afterthought to create 4 aspect signals :shock: :lol: )
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dkightley
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Re: Working Signals

Post by dkightley »

Here's some at 0.8mm o/d brass tube that has a 0.3mm bore:
http://www.dccsupplies.com/item-p-10204 ... 3-pack.htm

And here's some 0.1mm solderable enamelled wire:
http://www.ebay.co.uk/itm/0-10mm-ENAMEL ... 1232138429

Using two wires to supply the red and green, and with the tube as a return, you have a starter for a passable 3 aspect signal....assuming you know that red and green illuminated gives yellow! In theory, the tube should take 3 wires, so many permutations are possible!
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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dkightley
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Re: Working Signals

Post by dkightley »

Those 0402 LEDs are small, aren't they??!

And here's my first go at a prototype of a single aspect signal. Off:
signal0.jpg
...and on:
signal1.jpg
The cutting of the backboard and painting are a bit rough....but it's nearly there!

I'll try a red/green next.....once I confirm which goes on top!


btw The wires are soldered!! :shock: :shock:
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Doug Kightley
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martink
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Re: Working Signals

Post by martink »

You've actually got it working - impressive. And pretty much to scale too. Assuming that the pics show the back, all it needs now is some black paint to mask the light.

At the risk of telling you something you probably already know, if you are going to use two LEDs for a 2-aspect signal then a good trick is to wire the LEDs back to back so that you only need two wires rather than three. And one of those can be the brass signal post itself so you only have to run one wire down inside. This does slightly complicate the control side, so you need a DPDT configured as a reversing switch instead of a simple SPDT.

For multi-aspect signals, the red aspect should be at the bottom - the rule is that it is supposed to be the closest one to the driver's eye level. By the same rule, for old-style ground signals the red is usually at the top. This is the opposite of road traffic lights, where the goal is to lift the red as high as possible so that it can be seen over other traffic.

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dkightley
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Re: Working Signals

Post by dkightley »

Thanks Martin for confirming the red goes at the bottom. I don't need to try and work it out from the grainy Forth Bridge cab ride video on YouTube!

And thanks for reminding me about the back-to-back wiring trick....I'd forgotten about it! The tube actually can take three wires, so there's plenty of room (...What!!! You may exclaim!) for wiring a few more lights. I've used 0.5mm OD x 0.3mm bore brass tube...which as you've already commented, looks about right...and the wire is 0.1mm magnet wire.
Doug Kightley
Webmaster here and volunteer at the National Tramway Museum http://www.tramway.co.uk

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