Mod/build: MT-G2 & dual Nichia 219C headlamp

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Mike C
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Mod/build: MT-G2 & dual Nichia 219C headlamp

I’ve made a few headlamp prototypes in the past but all have had mechanical switches. Now it was time for one with momentary switch as I have support for it in my new driver design. The idea was the same as always, a headlamp with separate spot and flood LEDs with independent brightness control of each. I had a couple of these real cheapo 3xAAA headlamps I bought specifically to use as prototypes, now with momentary support I could do it rather easily:

However, those two flooders got me thinking. I had a couple of these headbands with 2 × 18650 boxes that where parallel wired:

I’ve always loved the MT-G2, so why not make a headlamp with one? I can’t just take any flood LEDs as they are going to be accompanying my favorite, so why not two Nichia 219Cs connected in serial, and convert the battery box to serial?

First up, rip out the driver board, open up the center hole a little and file down the flood LED holders:

Hack up the original driver board so I can use it’s momentary switch as it’s located perfectly:

Nichias fit next to the MT-G2, just clearing under it:

I used thermal adhesive to glue on a copper washer on the back of each 219C so they match the MT-G2 in height, and then on with a piece of aluminum from another butchered headlamp.

I then used the original 3 x AAA battery holder to keep everything in place, but hacked it up so I can have the MCU close to the aluminum plate to monitor the temperature. This is just a temporary solution, I have to add more heat sinking or the MT-G2 will heat up way to fast. The cable I’ve used is from a car cigarette lighter extension cable.

The battery box was fairly easily converted to serial. There is room inside for my thicker cable after removing the charger circuit:

The driver is a ATtiny1634 based one I originally made for other headlamps. As this one is for 2S, and 7135s are somewhat unreliable for higher voltages, I opted for 12V AMC A705NGTs instead. They are 16 of them in total, 8 for the MT-G2 and another 8 for the pair of 219Cs:

So now I have a something else other than what I had planned… I knew the MT-G2 in this crappy shallow reflector would be nothing even remotely close to being a spot LED, but I couldn’t help myself, I had to do it. Now I just have to think about a decent UI for independent brightness control of the paired Nichias and MT-G2 with a single momentary switch. I’m also considering installing a slave FET for the MT-G2 as 8 x A705s doesn’t make this into the blaster it could be.

So yeah, real nice LEDs in a totally crappy host, and with the adhesive I’m sort of committed, but it wasn’t planned at all. I just couldn’t help myself…

Edited by: Mike C on 08/18/2017 - 13:32
FmC
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Pretty cool conversion – So much polish, it’s hardly a ‘turd’ any more Smile

Would be good to see a headlamp build in this year’s OL Comp…. Wink

MRsDNF
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FmC wrote:
Would be good to see a headlamp build in this year’s OL Comp…. Wink

I think ltp may be thinking about such an item.
Mike C wrote:
I knew the MT-G2 in this crappy shallow reflector would be nothing even remotely close to being a spot LED, but I couldn’t help myself, I had to do it.

Nice. Smile
I admire your skills in all respects immensely. Thanks for sharing and looking forward to the update, as mad as it will be. Beer

 

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Mike C
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For a competition like that you need to put a little effort into how it looks… I never do that, don’t have any fabrication skills at all Smile

I re-used a SIR800DP FET from some old driver for a slave board and hooked it up to a the driver’s pin for secondary switch (this light only has one switch).

When I turn on the FET it produces a pretty darn bright wall of light… and it burns fast. I can only have it one for about 10 seconds before I see smoke and smell burnt plastic Crazy

LightRider
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Very fun! Where do you get those headbands with battery carrier?

Mike C
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I got the headbands from AliExpress. I bought from a few separate shops but they all came from the same shipper. Here are two of the links I used:
https://www.aliexpress.com/item/headlamp-headlight-Headband-head-Belt-in...
https://www.aliexpress.com/item/headlamp-headlight-Headband-head-Belt-in...

There is a charger circuit in them that I wouldn’t use and the cable is crap if you want any kind of output, but the box is fairly easily modded to 2S (the only reason why I got them).

Mike C
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I think I’ve just found a worthy host for this driver and LED combo, the Fenix HP30R Love

I love the HP25R as a host, great quality and mod friendly. This one looks promising. Unfortunately it has a belt worn battery case instead of box on the headband, but I can just use another one of these battery boxes from AliExpress.