OLcontest, modified light: 20cm fresnel lens thrower

The big optics invite woodworking over metal work (too heavy, too much expensive material), so these lenses are right in your league :beer:

Thatā€™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 piecesā€”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 meltā€¦!?

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 :cowboy_hat_face:

I guess these could be handy :smiley:
https://www.aliexpress.com/item/32920891109.html

You know you can do it. Iā€™d suggest a beer to the student that makes the best batman stencil. :stuck_out_tongue:

Iā€™d love to do the also MD but you know as well as I do it wood never work. :frowning:

What/who was your source?

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 drugsā€¦

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.0.0.19d315a3EZSPBz&browser_id=66b1ef171b05438fb64eff5ede7df8ad&aff_trace_key=8a9fcaee55ca4f97ad04c20e01d01302-1603223217706-05977-UneMJZVf&aff_platform=msite&m_page_id=uwt5f3ysax4carj3175b3e1b8271a9c5879ed5cc9b&gclid=&*imgsrc*=ae01.alicdn.com%2Fkf%2FHdaa45cc53f114786a1a4c40ca2433fd0A.jpg_640x640Q90.jpg\_.webp

Thanks.

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That is amazing, very well done djozz :+1:
Now that is thinking outside the box ! I never thought a Fresnel lens could do that !
You could do a Batman thingy in the clouds too.
No doubt this years competition is heating up :smiling_imp:
BLF has other forums beat easily :wink:
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This is very coolā€¦. something to think about

I tried a bat stencil, sawn out of thin aluminium with a fret saw, but I made it too big, the edges of the wings do not receive enough light so they appear not sharp.

So it must be made tinier, not sure if that can be done nicely with a fret saw. And Iā€™m not sure about batman either, maybe I will end up with something entirely different :partying_face:

Cool! :beer: :+1:

Jeff51 just posted about a batman projection contraption that uses a 100,000 lumen Imalent flashlight as a light source, and a 25cm fresnel lens with fairly long focal length. Pretty cool too, but not as silent, and maybe a bit less throwy than this one.

The sky is the limit :sunglasses:

Looks pretty good actually! :smiley:

:laughing: :+1:

Good effort djozz. :smiley: :beer:

Tnx.
Today I got the 14AWG wire in so I could finish the battery carrier. I chopped the front section off the flashlight head 4mm above the shelf and sawed two grooves in the remaining rim to lead the ledwires to the side. Had to ream the holes in the shelf to 4mm diameter for these quite massive wires. Smoothed everything with sand paper so there were no sharp edges to cut into the wires. The wires were fixed in position with a good bit of kapton tape, does not look extremely profi but you are not going to look inside the lamp daily.
In the picture I show the old 18AWG wires too, so that you can see that 14AWG is a whole lot thicker.

I was lucky because with a 40T at 4.12V I measured 19.85 amps now, precisely what I was hoping for :slight_smile:

So now that the battery tube was shortened, I could check the maximum flood setting of the lamp, with the slider towards the lens with the battery tube touching it.

In the picture the flood looks a bit less wide than in reality because of the wide field of my phone camera. Trees are at 25 meters as always. (it looks like I borrowed Flahoholicā€™s van for the beamshot :slight_smile: )

:slight_smile: Nice