OLcontest, modified light: 20cm fresnel lens thrower

:smiley:

Well done! :+1:

That box looks great now.

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

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.

Sweet :heart_eyes: :star:

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.

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.

:+1: :beer:

“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.”


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

Waiting for that to come ………… Djozz Van Helsing :smiling_imp:

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

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

I could have a try on the bat signal, but it must be cut out of a strip of metal within a 10x10mm area :open_mouth:

The starfish (zeester)?

I know, djozz, you will be playing Nightcore’s Vincent “Starry, starry night” while pulsing the star to the rhythm.

Good work. :+1:

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.

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

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…!?

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