BLF GT (preliminary) modding thread

Thank you, goshdogit.

Emiter swap is so little mod than I don’t plan to engrave nothing.

You might be right, but with a second measure (15m) smaller than the first one (10m), I have interpreted that the beam was already collimated at that distance.

In any case, my luxmeter is very cheap and crappy. I want to think that the actual results are better.

if the further measurement is lower your beam is either not focused to infinity but rather to something under 15m or your measuring method is off

I emailed them about them and they asked what were they for, I answered honestly and they just ignored me afterwards… :rage:

How did you convince them? Got a spare you could sell? :money_mouth_face: :wink:

I am working on a CFT-90 driver for GT

TN42 design finished

Ancient Chinese Secret…been dealing with Lumintop for years, I did a SD75 XHP35HI and needed Smooth reflectors, they made them for me. I sent pics and written details of the builds, the rep at that time was Will, he thought it was very Cool. I guess I’m on their Cool list? A shout out to Convoy, Thrunite, and Phoenix they are great to deal with also, at least on my end. :wink:

@ Lexcel

which input voltage?

carrier mod necessary?

I would like to mod my GT with an XHP70.2, someone can kindly tell me which resistor to replace on the original driver, and possibly which value to use?
Thanks.

I have posted this information before somewhere.

You need to replace the 2512 3W resistor with either a .050ohm or .040ohm. The .040 is not officially recommended but it has been working fine in my light for months now.

The biggest issue is the xhp70.2 mcpcb, they are hard to find.

I am trying to talk lumintop into making a batch of them and I think they might do it. Although time will tell for sure.

Tomorrow evening Djozz and I will measure our BLF GT’s in the basement floor of my appartmentblock: we have an indoor beamshot location of up to 45 meters……….
should give us some decent throw numbers indication.

Me or Djozz will post the results.

Cheers
Nico

I purchased a R047 from here

Now I noticed that TA said 3W power the link is for 1W power, would that still work? or do I risk effing something up?

That resistor while technically ok is only rated for 1W. The resistor needs to be rated for 3W for long term reliability.

I have yet to find a reasonably priced 3w .047ohm resistor myself, so I just recommend the .050 and .040 now.

Thanks for the clarification TA, I just noticed it! The cheapest I found was $20 for 100 pieces… Will this one work?

https://www.ebay.com/itm/100PCS-X-Bourns-3W-2512-0-047R-47MR-0-047-OHM-1-RES-Metal-Film-Chip-Resistor/332133259856?epid=574292028&hash=item4d54af5a50:g:YTsAAOSw32lYq0X3

Yes, that would work but please don’t spend that much on a resistor. Better to just get an 050 or 040 for less then $1.

Or for that kind of money wait until my TA drivers are finished and buy one of those. It will give you a lot more performance from the xhp70.2.

thanks, I still did not understand what is the resistor to change, over the weekend I will try again.
these seem right and at a good price
https://m.ebay.it/itm/10x-LRP2512-R040-1-Resistor-sensing-SMD-2512-40m-3W-1-55-170-C-VIKING-/192399386351?\_mwBanner=1

or am I wrong ?

Yes, that one will work fine.

Once you look at the driver it will be clear which one it is. It is the only resistor of that size on the driver. Right now it should say 91 or something on it.

I sure won’t buy @ $20, will keep looking around or just wait for your driver boards, I’m not in a hurry…

Thanks TA, I’ll wait for your drivers.

Lexel wrote: “I am working on a CFT-90 driver for GT”.

Hmmmmmm……I think I already know where part of my holiday allowance will go to :smiley:

Djozz and I did some measurements this evening, at 21, 13 and 8 meters.
Djozz’ light performs quite a lot less less then mine, so we measured only my light at all three distances.
And Djozz has his work cut out to find out what’s wrong with his light. :rage:

Results:

Djozz light: 21 mtr = 832.167Cd
My light at 21 mtr = 1.142.190Cd
Mine at 13 mtr = 1.139.060Cd
Mine at 8 mtr = 1.142.336Cd

(We measured with Djozz’ calibrated Gossen Luxmeter and deducted the ambient light @ 61Cd).

At first I was baffled by the lower readings at higher distances and thought it might have to do with the convergance of the light but I saw others posting
similar results, so……it looks like the BLF GT is already fully focussed at 8 meters.
1.142.336Cd is not bad, not bad at all, but still a little bit lower then I had hoped for.

So, thinking of replacing the led with the latest bin and maybe giving it a little more power as well, say 2,8A instead of 2,5A.
Then again, a custom Lexel driver and a CFT-90 might be really nice as well :wink: :wink: :wink:

Cheers and wishing you all very bright days and nights,
Nico

Driving a XHP70 with just a 0.047 Ohm resistor will be disappointing at 6V
This would result in 5A
Also switching frequency would not be ideal, the diode would be quite close to its limit

I changed the Inductor, MOSFET, capacitors and diode with better parts for higher currents also the switching frequency will be set to a point where the drivers efficiency gets optimal
Also reducing the current sense resistor and lowering the current control voltage divider helps reducing heat

I should get next week the 20-40A synchronous Buck driver boards that I developed for CFT-90 and going to assemble and test the first prototype