SST-50 homemade spotlight

[saltytri]

Holy Smokes, that is way beyond cool! Thanks for posting this - it is unusually interesting. :twothumbs

 

[Al Combs]

Wow. Really impressive first post. Nice work.:twothumbs

and

:welcome:

 

[wquiles]

Great project

 

[Al Combs]

I'm not sure if this is something you've already considered in your regulator setup. But here is a good thread discussing a potential problem using a voltage regulator instead of a constant current regulator with an LED. Luminus says the SST-50's Vf temperature coefficient is -4.4 mV/ºC @ 1.75 amps. I'm guessing that value goes up at higher current levels. KillingTime mentions in post #3 of that thread after a 30 minute runtime test, the Vf of his SST-50 had dropped enough to trigger his regulator's hiccup mode for short circuit protection at 10 amps. In post #19, pepko describes his use of a thermistor to compensate for the LED's drop in forward voltage. I don't know if he set that up by trial and error or what. Of course the best would be a good constant current regulator.

 

[EasyB]

oh Lordy!!! I just soiled my boxers @ that beamshot.

Awesome work, very impressed with your fabrication skills.:thumbsup:

Curious...
How come so much light is being spilled out to the immediate sides? The light thats illuminating you as you hold it... where is that light coming from? Is it being reflected back at you off the lens surfaces?

Yes, I think it's just from the light that's peeking around the collection lens and from scattering off the lens surfaces. Gives you an idea of the significant amount of light lost upon going through lenses.

Al Combs, I did consider the problem of current runaway, but I don't have a great solution, I just set the voltage so I have a bit of room for current increase and I think it's pretty well heat sinked, just what the original poster of that thread did. I monitored the current for few minutes and it was fairly stable.

 

[vestureofblood]

Wow!! Very unique, that was more than I was expecting when I walked into this thread. Great job.

 

[aurum]

Hmm ... I don't see any pictures

 

[scott2907]

No pictures!! Help I need to see this!!!
:mecry:

 

[bansuri]

Hmm ... I don't see any pictures

Same here, I'm starting to wonder if all the other posts are tongue-in-cheek?

 

[EasyB]

Sorry everyone who hasn't seen the pics, you are really missing out.

I was hosting the pics on some space provided to me by my school, but the whole system seems to be down right now. I'll put them somewhere else if I need to, but I hope they will be back up sometime soon.

 

[Walterk]

omg.... 330mm diameter.....!!
missed that part earlier.

 

[Vbeez]

Interesting indeed

 

[DM51]

Sorry everyone who hasn't seen the pics, you are really missing out.

I was hosting the pics on some space provided to me by my school, but the whole system seems to be down right now. I'll put them somewhere else if I need to, but I hope they will be back up sometime soon.

You might want to consider a proper hosting site such photobucket.com (or equivalent) for your photos. It is important to CPF that images will be available long into the future, so people returning to threads for reference can still see them. Your school is not likely to want to host your images after you have left, and its server has already proved less than reliable anyway.

 

[download]

Wondeful mod!!! :welcome:

 

[Walterk]

Great and clear pics! Like the build.
Makes sense to use a sst50 instead of the much favoured XRE to have a strong spot.

 

[Illum]

any word on selling DIY reflectorless throwers in the future? or at minimum build plans and material recommendations?

 

[jspeybro]

oo::huh: nice!

A short focal length lens collects most of the light from the LED and the large fresnel lens focuses it far away. The LED is actually inside the focal length of the small lens, creating a virtual image that the large lens sees. The large fresnel lens is 13" in diameter.

Did you just get the lenses and then put them together to get it in focus, or did you calculate it specifically and then source lenses? or both, caclulate for available lenses?

By putting the LED slightly further away from the first lens, you could probably reduce the size of the second lens at the cost of less collected light. Also a shorter focal length of the second lens could reduce the size even without changing the position of the first lens, but usually large lenses with short focal lengths are not very common.

If you're using lenses from Edmund Optics, your getting quality lenses (which have a price of cource), but the result is just great.

This actually looks much like something I'm going to do with a Luxim light emitting plasma light in the near future (still waiting for the light to arrive).

Johan

EDIT: would you care to share a picture taken from the side and of the total setup when the light is on (maybe dim it a bit not to overexpose the camera) so we can see the light path between the optics?

 

[Walterk]

Side mug shot would be interesting indeed!
Ask someone to blow some smoke in the area to make it easier to capture on film...

 

[EasyB]

oo::huh: nice!



Did you just get the lenses and then put them together to get it in focus, or did you calculate it specifically and then source lenses? or both, caclulate for available lenses?

By putting the LED slightly further away from the first lens, you could probably reduce the size of the second lens at the cost of less collected light. Also a shorter focal length of the second lens could reduce the size even without changing the position of the first lens, but usually large lenses with short focal lengths are not very common.

If you're using lenses from Edmund Optics, your getting quality lenses (which have a price of cource), but the result is just great.

This actually looks much like something I'm going to do with a Luxim light emitting plasma light in the near future (still waiting for the light to arrive).

Johan

EDIT: would you care to share a picture taken from the side and of the total setup when the light is on (maybe dim it a bit not to overexpose the camera) so we can see the light path between the optics?

I actually went through anchor optics, which is connected with edmund optics somehow. The lenses were fairly inexpensive compared to what you'd get at edmund optics. I don't think I had this exact design in mind when I purchased the lenses. Got a bit lucky I guess. I picked the small lens because it has a very high diameter:focal length ratio. 47mm diameter, 21mm focal length. I picked the fresnel lens because it's big and round.

I'll try and get a good side shot with the beam on.

 

[JonN06]

That is super cool. I need to learn how to do this stuff. Thanks for showing it off. :thumbsup: