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Let there be light!


Will Vale

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Whitemoor has an awful lot of quite distinctive modern lamps - any picture shows them quite well. I need at least three, probably more.

 

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I was thinking initially about using this N-scale Viessmann lamp since they should only about 50mm tall in 4mm, but I wanted to try and build one first since the shape looked relatively straightforward, and the Viessmann lamp doesn't have the wider section (cable cabinet?) at the base of the post. I bought some 3.2mm square brass tube (since the inside dimension was small enough for a 1.8mm "lighthouse" LED) and a couple of lengths of telescoping round tube (I think 1.6 and 2.4mm) from the model shop on my way home this afternoon. The reason for doing this now, when I should be weathering track etc., is that I'm going to be in Germany for a couple of days in the near future, so I wanted to know whether or not I need the Viessmann lamps before I get there - they're cheaper there!

 

Anyway, back to the home-made lamp - it's all brass, soldered with a 20-watt iron and electronics solder. I've never built anything like this before - I used superglue for my one etched relay box - so you can probably imagine I'm pleased as punch at how it turned out :D

 

The shade is U section cut from the square tube by filing away two edges and peeling out the resulting strip with pliers. I then filed down the web to the base of the U at both ends, one straight, and one diagonal, so I could fold them up to make a sort of trough. I didn't get the diagonal end matched up very well, but I filled both ends with solder and filed them down flat. I've had a go at adding some of the bevels from the prototype, although I think I need a vice to get the long slope of the sides since I can't hold it steady enough with fingers! The sharper slope at the back was easier and is worth doing since that seems to be quite a strong feature on the real thing:

 

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Once cleaned up, the lighthouse LED was a push fit into the channel (only in one direction though) so mounting the shade was pretty easy. Since the post is quite visible at the back of the shade, I fixed the LED so it was nearly flush with the top of the post. One leg is trimmed very short and has a length of fine wire (Howes decoder wire) soldered to it. I don't have any really fine heat-shrink, so I've tried to keep the insulation neat, and theres a strip of masking tape to ensure the end of the wire can't touch the shade. The insulated wire runs down the post in what I assume is the usual way, with the post itself being the other conductor.

 

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The LED isn't exactly discrete, but it's not too visible below the shade. It would likely be possible to do something better with a surface mount LED, but they look difficult to solder! I'm also thinking that some kind of diffuser (clear plastic tube/sprue sanded matt?) would make it look a bit cleaner.

 

For the base of the pole, there's a shorter length of the larger tube with a taper filed into the top - it just slides over the inner. I haven't cut anything to length yet, but I suspect I'll trim the outer tube exactly to size, and leave the inner tube long for planting.

 

Construction time was a bit over an hour, plus half an hour for a false start on the shade - I tried using small snips rather than filing to cut the webs and ended up with mangled awfulness! I also learned a useful lesson about LEDs - you need a limiting resistor even on if you're using 2 AA batteries :( So I burnt out my first LED and had to desolder it and mount a new one. Ah well :P It looks quite nice lit up though, and probably cost about a pound to make. Now I just have to make two more, which should be interesting since the shade dimensions for this one are eyeballed rather than planned properly - I wasn't expecting to get something I could use, to be honest.

 

Proof it works :D

 

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5 Comments


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Hi, that lamp is looking really good!

I find that even with proprietary LED lamps,

from the usual suppliers,

I have to use additional resistors -

otherwise they are over bright.

 

I especially found this to be the case with some buffer-stop lamps I bought from express models. Hopefully, the extra resistors will protect my lamps further.....?

 

Also, I fitted some German made LED lamps inside a depot building.

I was being lazy, and wired them in circuit - along with a depot-wall lamp,

by Express models - Big Mistake!

The wall lamp blew, after not much use!

I suppose the other lamps had very different resistance values.....

But I won't be doing that again in a hurry.....

 

Nice neat job,

and as you say, with the cover on, you can't really see the LED.

 

Best

Marc :D

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Guest jim s-w

Posted

Nice work Will

 

Looks spot on to the pictures you have linked to

 

Cheers

 

Jim

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Very impressive Will. There is a seller on ebay (ledbaron) who sell the surface mount LEDs with wires soldered on, for quite reasonable prices.

 

They're in Germany, but I'm fairly sure they'll ship to NZ.

 

Having said that, you probably don't need to bother, as you say the LED isn't really that visible.

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Will the proportions look good to me - I hope the other two go together as well as this 'trial' one :) Save the money from the Viesmann lamps for some more scenic treatments!

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Thanks for all the kind comments - it spurred me on to make another three today (since the inner tube worked out to 1/4 of a length of K&S) which went pretty quickly and are a bit neater than the prototype (less solder inside the shade) to boot. I think I'll put a pad on the far side of the track where the relay cabinets are going to be and install a lamp there.

 

There is a seller on ebay (ledbaron) who sell the surface mount LEDs with wires soldered on, for quite reasonable prices.

I'll look into this - although possibly for some other lights now, see below. Thanks for the suggestion :) Thinking back maybe you mentioned them as the source for your 37 cab lights?

 

I was able to reduce the clutter below the shade by mounting the LED the other way up, so the leg soldered from the post is at the top, and the wired leg at the bottom. This also means there's no need for tape insulation (the wire join is short and in free space) and it's possible to make it a bit more compact - I ended up cutting the short leg back to about 1mm. I'll take a picture at some point but it's more-or-less an upside down version of what I showed above.

 

Before working this out, I tried a couple of other schemes, like bending the legs 180' and mounting the LED pointing down, but it was too easy to either file too much off the lens (dead LED) or snap the legs doing the bend (unusable LED). As-is is good, since it only uses 90' bends and the lens can remain intact.

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