Homemade headlight reflector with LED

[graffen]

Latest project ....
A reflector with light for my narrow-gauge locomotives.
The diameter of the reflector is 4 mm.
The LED is 0.5 x 1 mm!
The reflector I made out of aluminum from oven trays.
I took a nut of the right diameter and slowly pushed the aluminum with the rounded top of the hat from a ballpoint pen.
Then I rough cut the edges and filed it to shape with a needle file.
I then drilled a 0.8 mm hole in the center of the reflector.
I glued the LED to the backside of the reflector with epoxy.
The LED is a bit too white, so it'll get a drop of Tamiya transparent orange.
Then I'll take Microscale Crystal Clear and fill the reflector so it gets a lens.

[tehachapifan]

Wow! Excellent work!

[Dave Schneider]

Love to see how the lens turns out. I need to do a double headlight inside of a round housing for my HO Walthers H10-44. I was thinking of doing something similar. Nice work!

Best wishes,
Dave
 

[peteski]

Nice job!  Too bad that this can't realistically be done in N scale.
This reminds me of the installation tips in the MV Products lenses (going back about 40 years, long before small SMD LEDs were available).  They manufacture ready-to-install headlights consisting of a parabolic aluminum reflector filled with clear resin to simulate the glass lens.  They suggested drilling a small hole through the reflector where the light-bulb would be and placing a grain-of-wheat bulb right behind the hole. 

[narrowminded]

Nice job!  Too bad that this can't realistically be done in N scale.
This reminds me of the installation tips in the MV Products lenses (going back about 40 years, long before small SMD LEDs were available).  They manufacture ready-to-install headlights consisting of a parabolic aluminum reflector filled with clear resin to simulate the glass lens.  They suggested drilling a small hole through the reflector where the light-bulb would be and placing a grain-of-wheat bulb right behind the hole.

If that would work, the light placed right behind a hole in the reflector, I could probably machine a reflector small enough.  The fear to me would be that the hole would need to be so large that the reflector would disappear, be drilled away.  Any idea how much of a hole would be sufficient?

[peteski]

If that would work, the light placed right behind a hole in the reflector, I could probably machine a reflector small enough.  The fear to me would be that the hole would need to be so large that the reflector would disappear, be drilled away.  Any idea how much of a hole would be sufficient?

Good question!
With today's relatively bright white LEDs, maybe a 0.005-0.010" hole might work?
With the LED placed directly behind the hole. But with such a small aperture (of placed directly over the LED die) you might be getting more of the blue light than the yellow light emitted by the phosphor (combination of both is what produces the "white" light).

[narrowminded]

Good question!
With today's relatively bright white LEDs, maybe a 0.005-0.010" hole might work?
With the LED placed directly behind the hole. But with such a small aperture (of placed directly over the LED die) you might be getting more of the blue light than the yellow light emitted by the phosphor (combination of both is what produces the "white" light).

That should be doable.  Do you have any headlight diameters in mind?  The bore that the lens should fit?  Nominal would be sufficient for this speculation.

[graffen]

This is how the light reflector looks installed.

The hole I made in the reflector to fit the 0402 SMD LED is roughly 0.5-0.6 mm.

[narrowminded]

That looks good!  I think that the concern with doing this is N scale is that a hole of that size could be 2/3 of the diameter of the reflector and may not look so good.

[DKS]

That looks good!  I think that the concern with doing this is N scale is that a hole of that size could be 2/3 of the diameter of the reflector and may not look so good.

Things may look quite different when the LED is illuminated...

[peteski]

This is how the light reflector looks installed.

The hole I made in the reflector to fit the 0402 SMD LED is roughly 0.5-0.6 mm.

It is a gorgeous model, that photo is not showing the headlight very well. From the angle the photo was taken the lens doesn't even look like it is transparent.  It is sort of muddy color with a different color dot in the center.

Narrowminded, I'm not sure but I think standard Diesel headlights are 5" or 6" in diameter, and steam loco headlights are quite a bit larger.

[narrowminded]

Things may look quite different when the LED is illuminated...

Do you have any experience or educated guess how an .008" +/- hole might work?  And the headlight diameters that would be useful would be 7" to 9"?  And is that the bright reflector center or the full diameter including housing/ ring?  I would be willing to try this as the dimensions don't strike me as impossible but would want to make something that might actually be useful.

[Lemosteam]

Do you have any experience or educated guess how an .008" +/- hole might work?  And the headlight diameters that would be useful would be 7" to 9"?  And is that the bright reflector center or the full diameter including housing/ ring?  I would be willing to try this as the dimensions don't strike me as impossible but would want to make something that might actually be useful.

@narrowminded , make sure the radial curvature inside is parabolic to focus the reflections and not a radius, LOL