OLcontest, modified light: 20cm fresnel lens thrower

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Yokiamy
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Awesome!
I love these build threads

WTB: Jetbeam TCR-1 or Sunwayman V10R Ti

Dr scott Diabol...
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Awesome! Following intently.

I’m in the design phase of what may become a 1000-1500 watt MH HID based searchlight with a 24” parabolic reflector. Horribly inefficient and messy, but I’m looking for the most visible beam possible, not max CP or max throw. I also have a cheap A4-sized fresnel and an old 250 watt halogen incandescent worklight that I’m experimenting with. It’s only 4000 bulb-lumens and a filiment length of about 100mm, so I don’t expect much. But we shall see.

MRsDNF
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Big Smile You mad bastard. I mean that in the nicest possible way. Beer

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

Grigio
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Nice build! That box needs a few coats of paint or lacquer, as well as a name / model number and a logo! (And a groupbuy!) Wink

djozz
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At your service Smile

Today was a quiet sunday in partly lockdown Amsterdam, and I could do a couple of things.

First a lens cover. The nr1 vulnerability of a plastic fresnel lens lamp is that the grooved side of the lens is on the exposed outside of the lamp, and any dirt/grease/fingerprint will be impossible to remove without damaging the surface. So a cover is essential for any moment that the lamp is not in actual use. I made the cover from polycarbonate which is tough and flexible. I used a small slat to create a groove at the underside of the lens that exactly fits the cover thickness, so that the cover can be slit in the groove while bended a bit and when it is pushed down it springs into position against the lens.

Now I removed the slider, the fan and the fresnel lens and did some cosmetic things to the box and painted it. I likely would not have done this if not because it is for a contest, which shows what a contest does to people, or just me Party
Knowing well that this is a plain square plywood box, and that any attempt making it look like a slick light is quite hopeless, I still went for some detailing, and by making it bright red it might even give a slight impression of being fast and furious? Probably not Facepalm

The inside was spraypainted with a matt black paint sold as “camouflage” Cool

The outside received a base-paint first, and then after some slight sanding, bright red!

That is all for today. Next job will be shortening the battery tube by chopping part of the head of the SD2 off, so that a wider flood can be obtained. And changing the long 18AWG ledwires for 14AWG ones, in the hope to get the 20A sweetspot for a well-cooled SBT-90, but I can not do that yet because the 14AWG wires are still somewhere in the mail between Hobbyking and my place.

And I have a cunning plan for a fun detail… Big Smile

MRsDNF
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looking at the box that looks so innocuous, one can only be amazed at what emanates from it. Scary.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

djozz
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Big Smile

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Well done! Thumbs Up

That box looks great now.

I’m looking forward to your long-distance beamshots. Cool

djozz
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flashburn wrote:
Cool The beamshot says how sick this is. Nice work. Love
The red finish gives it the epic appearance it deserves.

There is just one thing I do not understand: Why did you wire the fan in parallel to the LED? Why a fan anyway, is it to protect the fresnel from melting?

Could a glass plate do a similar job, to spread the heat and keep off UV radiation? The air gap between the glass plate and the fresnel could be filled with an extremely fine layer of Canada balsam, to minimize losses. This construction would also enhance stability and beam quality. A spin coat on the inside could serve as antireflective. Or a glass plate glued in front of the fresnel, it could protect the fresnel, but to achieve this, vacuum is needed to pull out bubbles in the cementing process, due to the ridges in the fresnel. just running crazy… Blushing


The fan is because most of the light never exits the lamp and is absorped by the dark-painted wood, that is maybe 20W of heat. The fan causes a minimum of air circulation to get rid of some of it. I do not expect much heat to build up in the lens, maybe a bit in flood position when the led is closer, so the lens is cooled a bit too. The fan is parallel because that was easy, it draws maybe 100mA so it does not eat much of the current. The alternative was a dedicated battery for the fan, but it seems not needed sofar.

Your solutions using glass plates and such sound very fancy, I’m not sure if fancy is needed, it was certainly not my intention and everything works as it is.

MascaratumB
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Sweet Love Star

djozz
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Yes, a collimator could be useful for making better use of the light coming from the led, and in this design there is enough space and mounting opportunity for one.

But the original purpose of this lamp was pure throw, and every added optic will reduce that number to some extend.

If more light is needed: I placed the light engine on a slider, so that with the led moved closer to the lens, a flood beam is created, in the closest position I expect light extraction to be fairly good.

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Wow! Somehow I completely missed seeing this thread when it first appeared. Great stuff, makes me want to get my hands on an aspheric lens and see what develops.

Thumbs Up Beer
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djozz wrote:
Big Smile


“Relax Honey! We don’t need to call the police! Its just that crazy flashlight guy on the other side, testing out his latest ISS signaling device creation. Just like the other time, we will hear all about it in a few days on the NASA channel.”

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What happened to the die projection? Did you burn a part of the phosphor?! Wink

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djozz wrote:

…………………

And I have a cunning plan for a fun detail… Big Smile

Waiting for that to come ………… Djozz Van Helsing Evil

You are a flashaholic if you are forced to come out of the closet, to make room for more flashlights.

djozz
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Henk4U2 wrote:
djozz wrote:

…………………

And I have a cunning plan for a fun detail… Big Smile

Waiting for that to come ………… Djozz Van Helsing Evil


Agro already noticed the fun detail, although he did not guess it right. Smile
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Are you going to project the legendary ‘bat signal’ with this flashlight? Or better a ‘BLF signal’? Crazy

djozz
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Skylight wrote:
Are you going to project the legendary ‘bat signal’ with this flashlight? Or better a ‘BLF signal’? Crazy

I could have a try on the bat signal, but it must be cut out of a strip of metal within a 10×10mm area Shocked
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djozz wrote:
Henk4U2 wrote:
djozz wrote:

…………………

And I have a cunning plan for a fun detail… Big Smile

Waiting for that to come ………… Djozz Van Helsing Evil


Agro already noticed the fun detail, although he did not guess it right. Smile

The starfish (zeester)?

You are a flashaholic if you are forced to come out of the closet, to make room for more flashlights.

Agro
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I know, djozz, you will be playing Nightcore’s Vincent “Starry, starry night” while pulsing the star to the rhythm.
https://www.youtube.com/watch?v=kQtWSzOAslk

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Good work. Thumbs Up

djozz
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This is how the star is made.
Because I built in some tolerance, the die is focused at infinity when the slider is still 12mm short of the backside.

So when the slider is fully retracted, the focal plane of the lens is 12mm in front of the led, and the die projection is out of focus, creating a fuzzy larger spot instead of the smaller sharp square of the focused die.

So I positioned a cutout of a star (made from the lid of a coffee tin) 12mm in front of the led, which is sharply imaged at infinity by the lens, and because the led is only little out of focus, the throw is still not completely ruined (although I think it went down from 4Mcd to just 1Mcd).

Of course for maximum performance of the lamp, the cutout must be rotated out of the way.

If I find the patience I may have a go at a batman cutout, but it must be tiny, and the metal is tough.

djozz
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MtnDon wrote:
Wow! Somehow I completely missed seeing this thread when it first appeared. Great stuff, makes me want to get my hands on an aspheric lens and see what develops. Thumbs Up Beer
The big optics invite woodworking over metal work (too heavy, too much expensive material), so these lenses are right in your league Beer
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That’s really clever. i like how you added some styling to round off the sharp corners and edges. What about the notches on the side pieces—do they hold something or just a design feature?

i would guess that the fan has an internal circuit board for pwm of the motor current and LV dropout.

Somebody with 3d printing could make plastic masks to shape the beam. But maybe they would melt..!?

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

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Quote:
But maybe they would melt..!?

That remark inspires me. I once tried to find the techniques involved in making those sixties psychedelic liquid slides. I did not quite find out the fine details but I did find a person (in Zaandam I believe) who was the expert at the time, and he was not dead yet. I may have to contact him after all Steve
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MRsDNF
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djozz wrote:
Skylight wrote:
Are you going to project the legendary ‘bat signal’ with this flashlight? Or better a ‘BLF signal’? Crazy

I could have a try on the bat signal, but it must be cut out of a strip of metal within a 10×10mm area Shocked

You know you can do it. I’d suggest a beer to the student that makes the best batman stencil. Silly

MtnDon wrote:
Wow! Great stuff, makes me want to get my hands on an aspheric lens and see what develops. Thumbs Up Beer

I’d love to do the also MD but you know as well as I do it wood never work. Sad

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

MtnDon
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djozz wrote:
MtnDon wrote:
Wow! Somehow I completely missed seeing this thread when it first appeared. Great stuff, makes me want to get my hands on an aspheric lens and see what develops. Thumbs Up Beer
The big optics invite woodworking over metal work (too heavy, too much expensive material), so these lenses are right in your league Beer

What/who was your source?

kennybobby
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you can harvest big lenses from old projection TVs at the thrift store and cut them down to size, and people will nearly pay you to come haul them out of their house.

The liquid light film slides can be made mixing insoluble liquids such as water and oil with color tints of either paint type between two panes of glass. Another example is to use air to blow a drop of water across some fresh oil-based paint and enjoy the patterns that develop. Fun stuff to do on drugs…

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

djozz
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MtnDon wrote:
djozz wrote:
MtnDon wrote:
Wow! Somehow I completely missed seeing this thread when it first appeared. Great stuff, makes me want to get my hands on an aspheric lens and see what develops. Thumbs Up Beer
The big optics invite woodworking over metal work (too heavy, too much expensive material), so these lenses are right in your league Beer

What/who was your source?


I bought it a few years ago actually, on aliexpress. They are cheap (under 10 dollar for a 20cm diameter lens) and pretty good, here is a link, I expect it to be the same quality as the ones I got. I chose 200mm focal length as a compromise between the amount of light catched by the lens, and image quality (a very short focal length lens will catch/transmit a large percentage of the light but also show a lot of image distortion at the edges which will negatively affect the beam and throw).

https://m.aliexpress.com/item/32650652778.html?spm=a2g0n.productlist.0.0...

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