# Miniature "Holly Wood" spot light, ideas on how to do it?



## Southwest Chief (Oct 27, 2012)

I'm a model railroader and have been trying to figure out if it is possible to make a miniature spot light. 

Spot light meaning this type of light:

http://video.google.com/videoplay?docid=780797371550952729

I have a model in HO scale (1/87 scale) of this type of spot light. I can easily animate it to turn. I even have a miniature slip ring for the light wires so they can spin without twisting and eventually breaking. 

Here is what the spot light trailer looks like next to the movie theater on my train layout (the layout is circa 1958):








What I'm not sure I can do in this small size is make a light beam. I'm also not sure if I should use a bulb or an LED. Both would have to be pretty small. I'll likely need some form of parabolic reflector as well.

Any ideas/tips on how I might accomplish this?

And any possible online links to miniature reflector makers?

Thanks,


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## jspeybro (Nov 1, 2012)

For such spotlights, I'd suggest using a led with a small die and an aspheric lens or fresnel lens with the shortest focal length you can find.
This setup will image the LED at a certain distance, without any spill light like reflectors have.
The advantage of a led to a bulb is the small size of the emitter and thus the small beam size if the lens is properly focussed.

You talk about small, but don't give any dimensions. how big can the front diameter of the spotlight be?
I have some lenses of 20mm, but perhaps that is already too big...

Johan


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## Thr3Evo (Nov 1, 2012)

That looks really cool, I'm curious to how it'll turn out. I'll second small die with aspheric lens, just don't blind anyone with it, and also once you have the set up consider some kind of light fog or smoke to greatly increase the "saber" effect.


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## MikeAusC (Nov 1, 2012)

An aspheric lens won't look authentic with the big bulge out the front.

At least a TIR or Reflector will look authentic.

You can create a small Fresnel lens by cutting a credit-card size reading magnifier to the size you want - they're surprisingly good for a sharp focus.


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## jspeybro (Nov 2, 2012)

true, fresnel lenses will give best results. I think the hard part will be to get the led in that lamp.


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## Southwest Chief (Nov 2, 2012)

Thanks for the interesting ideas on how to do this.

The light housing measures a tiny 18mm in diameter with a 1mm lip around it so a total outside diameter of 20mm. The depth is small too, at only 7mm. So with these small measurements finding a lens is likely going to be my biggest obstacle.

A smoke/fog effect is a great idea to enhance any light beam. At least miniature smoke machines are readily available in the model train market.


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## Thr3Evo (Nov 2, 2012)

How about an smd led. I don't know squat about them but they look very compact and from the looks of them it seems they project most of their light forward since they are domeless.


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## Southwest Chief (Nov 2, 2012)

An SMD LED would work nicely. I've used these a lot on the train layout.

I'm not sure if SMDs are brighter then the "super bright" I have some familiarity with. Maybe a small chip LED might be have more light output.


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## DIWdiver (Nov 3, 2012)

I definitely think you want an SMD LED, because you want a really small die size and really small package. Super-brights tend to be in packages too large for what you are talking about.

I also agree that the hard part is going to be the lens. I doubt the credit-card sized fresnel lenses will have sufficiently short focal length. You may have to go to specialty places for those lenses. Edmundoptics has a 0.6" fresnel with 0.2" fl that might serve well.


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## Thr3Evo (Nov 26, 2012)

Any updates?


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## Southwest Chief (Dec 4, 2012)

Sorry for the lack of updates. I'm currently working on some other model train projects right now. But when I get to the spot light, I'll update this thread.


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