NEXT 75mm Zoom XM-L - 3.1Amp - 7x14500 - Buildlog w pics

I’ve been playing with leds for a few years now, and my favorite lights always have been the zoomies:

But the ones from the shops don’t go that large.
I built some bigger aspheric zoomies earlier; the Huygens Ultimate, a 250mm (XR-E) 2,1 mcd led lamp, and a 75mm (SST90) with 80kcd.
Usually I get inspired by build-logs or because I want to test how ideas can be combined and applied.
(All my previous experiments are on the other forum under same alias. I like postings to be illustrated, and Flickr supports that.)

This time I was aiming for a simple, compact and solid light.
Months ago I decided to go with this concept:


Moving the lens forward/batteryholder backwards, the led turns on, projecting from flood to focussed.
The O-ring is to give friction, holding the position without accidentally losing the head.
When the light is stored, the O-ring should seal the inners from moist and dust.

I planned to use 8xAA Nimh and XM-L direct drive, but DrJones pointed me at the AMC7135 combined with protected Li-ion. I adopted his suggestion as he is smarter then me.
AMC7135 for size:

Soldering the AMC7135 was difficult. Luckily I found someone to help me out with that.

I have three lenses that fit. Will choose after testing. One is old 76mm Ebay/DX, other is 75mm Thorlabs (preferred so far) and a 75mm Edmunds. The new DX 78mm doesn’t fit without grinding.

Will be using a XM-L T5 on copper star, powered at 3.1Amp by 9x AMC7135 from 7x14500 AW Protected cells.
The electronics and reed-switch will be housed in one out of 8 cell-bays.
On the front of the batteryholder a PCB will close the circuit from all batteries to the driver. On this PCB there will be a small spring with a magnet to activate the reed-switch.
That will need some testing and tuning to have it aligned properly.
Still thinking of potting the electronics or not. I like it to be durable, but do want the AMC’s to be cool.
Led and reed and magnet:

The longest wait so far was in finding a workshop that was affordable. Machining is done, very close to perfect, by using a conventional lathe and a CNC-mill.
As it would act like a piston a part of the aluminium has a longitudinal groove for pressure relief. When the light is ‘off’ , the O-ring seals the innerds.
The light will be anodized black when all testing is done.
Have to make some adjustments to recess some wiring, enlargeing the relief groove and sand/polish the aluminium to fine-tune the pressure from the O-ring.

Assembly in off/storage position

Assembly in on/focused position (45mm BFL)

This light is now about 1/3th finished. Will update posts or add a new post to this thread when I have more to share!

What do you think? Could it work?

Can’t see the pics

Sorry for that, it took me some minutes to write this down :wink:

Nice! Is it running off of 8 nimhs or 7 14500 lions? You said both.

Will use Li-Ion. Protected as it would be foolproof integrated protection for the cells. In case I turn dumb.

For the AMC7135 you get more juice out of the cell with the slightly higher starting voltage and the lower voltage-sag due to their chemistry.
Besides that, Nimh could have worked, also with the AMC’s for restricting the current to the led, safeguarding it.
I like it to have a runtime for more then an hour.

I’ve powered it with 2x3 AA Nimh and that worked great, straight at 3 Amp, nice figure. But now it will be more regulated, to halfway the cell.

There is quite some mass and surface area, but a higher current and thus more heat is not adding much in output. Measurable, but hardly to notice with the eye.

So how are they wired? Series or parallel?

I’d buy one in a heartbeat, seems like nobody wants to make a decent aspheric these days (with a reasonable price tag)

One thing I have been wondering, everybody keeps talking about dedoming LEDs but that is going to damage it to some degree and open it up to the air. Has anyone considered lapping and polishing the top of the LED to be flat, that way you don’t risk breaking it (as much) and keep the protective bubble protecting the LED.

Modding a J16 King or DRY to be an aspheric might pay off pretty well, I’d drop some cash on a kit on the spot.

The domes could be lapped maybe.. but I've read somewhere that you can deform it by heating it and applying pressure. I actually tried that on a already fried LED and the dome was easy to deform with some heat, but it didnt stay down.. maybe I would have needed more heat.

Getting some 2000 grit sandpaper and lapping one is on my to do list, but I don’t have a decent aspheric.

Anything out there that runs with the dereelight or 7g5 collimator but doesn’t cost an arm and a leg?

I gave up on finding a smaller light that has a pencil beam and just ordered a TN31, still would like a nice pocket thrower though.

Also, what about using a concave lens over top of a lapped t6 but before the main collimator, that would reduce the apparent size of the die to the main lens and could give a nice bump in lux.

I can’t wait to see the final light along with some beamshots. I might want to buy one :money_mouth_face: .

looking forward to the beamshots when you’re done also. i think a lot of people would be interested in something like this.

Actually, I recently read about a light using two lenses just like you described.. cant find it know, but I think it was some zoomie light from DX..

Pencil beam: Small Sun ZY-C10. 15 bucks, XRE emitter. Driver is crap imo.

@WalterK: Sorry for hijacking.. but I'm also eager to see some beamshots. But thats no flashlight.. thats a flashbarrel!


Great work!!! Looks Awesome…… I can’t wait to see the output.

WOW thats cool!!

Looks pretty cool to me.

Looks great!!! Looking forward to pics of it complete along with beam shots! :slight_smile:

Sorry if I missed it, but where did the big black cylinder come from ?

He machined it on a lathe/cnc mill.

Fantastic concept WalterK,it looks like a telephoto lens from a camera.Love to see beamshots when available,thanks for posting.

Howly $%~&!!! :open_mouth: Man, that’s the biggest zoomie I ever saw! :open_mouth: Can’t wait the final BigF*ckingLight and outside pics :stuck_out_tongue:
Great job!