Help: Stacking 7135 chips in Biscotti drivers (using XML2 LEDs)

Flashlight Modding and DIY Parts
4

Hi vwpieces!
Thanks for your answer, images and links! They will help on this :wink:

I retrieved the chips from the damaged drivers, and unless heat has damaged them internally, on the outside they look fine! 16x7135 chips ready to be stacked :smiling_imp:

I still have some doubts but I’m still searching to understand the process as a whole! Yeah, I’m not savvy to read well all the charts or at least to interpret them without searching a bit on the basics first (V, W, lm, and that stuff…).

1 doubt I have is: the tab on the back of the stacked chip (top), does it have to be soldered to the bottom one? I read some things here (How-To: Add 7135 chips to a Driver Board (Stacking)) but as there are no pictures, it gets hard to see how it is concretized!

On yours, they seem to be, but on Richard’s video, I guess he didn’t solder the back tab…

The 2 lights I am willing to give more power have different pills and hosts, not like the S2+.
The S2+ would be my third option as I would try the others first, as an experience.

Stacking 4 chips per driver would be a reasonable amount of heat and luminosity gained, I suppose, right?

About soldering the plate to the pill, I never thought about that, but would that be a better way to dissipate the heat, then? So far I was going to rely on the pills and on thermal paste, as I’m not a soldering expert too!

And on the zoomie light I modded, there was no shelf, so I needed to improvise :stuck_out_tongue:
Maybe I can find some copper around, or I can order from anyplace!

I’m starting to learn some things so I appreciate the help you and others are giving ! Hope I can give in the same way :wink:

Next week I’ll start to try the stacking and post about the process!

Thanks again!
And good luck in the employment issues as well :+1:

5

the center tab on the 7135 is the same as the single wide tab on the other side. Only one, technically needs to be soldered. I do it just the opposite of that video. I solder the fat single tab first, and then just drag solder across the 3 tabs on the other side. I had a problem (not really a problem, just getting the solder right), the first time I tried, but it really is pretty easy with the right tip. Best advice is use a lot of flux, and a good bit of solder on the tip.

6

Thanks for the answer Dusty!!
Well, so soldering the tab has to be with the bottom tab, not the edge of the driver, right? Or doesn’t matter if it is soldered to the driver too?
On the post I linked above it was said:

So, seeing this I’m kind of confused…

Yeah, I have to buy some solder flux, I’ve seen that it is really important on this kind of work and I have none! Gonna check on that too :wink:
My solder iron is not extremely thin, but it is not thick too! I’ve been adapting to it and to retrieve the chips I hadn’t a lot of trouble.
Thanks again :+1:

7

Thanks Man,
I like to solder the MCPCB down when ever possible, if its a Brass pill or a copper spacer. Others may have different opinions. I don’t have a light meter so I never really compared to thermal paste after maybe 30sec. I guess another way would be to run both lights on high and check temperatures against time.

8

Hey, you’re welcome :wink:
Hum, I guess that may be a matter of preferences too :wink:
I may try that option! I have a free pill in which I can test soldering before passing to the already built lights. If I go wrong, I’m not damaging too much :smiley:

No problem with the measurings, I was only wandering about that! I guess I won’t have many problems with hear dissipation on these pills:

Also, the hosts can handle that, I hope :partying_face:
Thanks again for the help vw :+1:

9

Never seen those pills.
Second is brass so you could solder the board in. Looks like a C8 but the spring on the bottom? C12? For that pill I would solder the board and also use thermal paste lightly on the threads. I hope it has a full shelf under the emitter board.

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The aluminium one is from my Brennestuhl, and I never seen any other like that. On the bottom is very thick, I had to drill and sand it to make a 17mm driver fit it!
The other one (brass?) seems a common pill for some lights with drop-in! Bought it in Kaidomain from AliExpress: 5.58€ 5% OFF|DIY 26mm(D) x 16mm(H) Kupfer Fahrer Säule Set für C12 LED Taschenlampen|pillar christmas|set up print screenpillar lamp - AliExpress

The outside bigger spring is to make contact with the host, and the inside spring is the driver’s one, that makes contact with the side switch of the flashlight!
The brass has shelf so I can solder the 20mm star plate in it! I think there’s enough space inside the pill to stack the chips.

For the aluminium one, I have to check as I struggled a bit to make it enter the pill, so I don’t know if they’ll fit…

Thanks again :+1:

11

Well, just tried the stacking… 4x7135 chips in a biscotti driver (8x7135)!

The good news are: the flashlight (still) works, even if I don’t feel it outputting more light (with freshly charged Sony VTC6)! :expressionless:

The bad news are: I just made a mess soldering and I think I damaged something because now it only turns ON on HIGH mode :person_facepalming:

(Well, not completely bad as this is supposed to be a outdoor light!)

So…I guess I’ll try again! I’ll order some new drivers and try again! That’s the only way: try, fail, learn, persevere, try again…hopefully don’t fail again, lesson learnt! :smiley:

I wanted to try this without solder flux , but that really may help a lot!
Also, I have to practice a lot soldering…a lot!!!

Thanks for the help so far :+1:

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Nice try MascaratumB. It took me years to be able to sort of solder these chips on. I believe my biggest problem was a tip that was to big and not hot enough temperature when I went to a smaller tip.

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Thanks MRsDNF! Hum, the tip may be a problem too, as I do not have a working station to regulate temperature! But I guess the flux will make the difference here! At least I hope so :smiley:

A month ago I didn’t knew how to solder and now I’m trying to stack 7135 chips! Maybe “baby steps” would have been better than the “go big or go home”… But…this was an experince! Next step: a pyramid of stacked 7135 chips :smiling_imp:

Thanks for your words :+1:

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I have a hungarian flashlight modding blog and I made a post about 7135 stacking.
Try to read it with google website translate. Or I hope the pics help something too.

1 Thank
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You good Zozz. :+1:

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Thank you! I have done so many stacking that yesterday I have done 3 convoy C8 with extra two 7135’s stacking per light in a little more than half an hour from working lights to upgraded working lights :smiley:

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:open_mouth: Wow, that’s perfection on stacking I would say! Thanks for the picture and for the link Zozz! Awesome!
For what I see you have a different method from the one used on Richard’s video linked by vwpieces: connecting juts the 2 tips from the extreme and connecting the middle by the tab on the back!! Maybe this can easy my work a bit!
That’s what people say “practice makes perfect” :smiley:
So…I’ll have to practice a lot… :person_facepalming:

But I guess I’ll need a thinner tip for the soldering iron and also the flux to make it flow better!!
Thanks again it’s very useful :+1:

18

I stacked two 7135 to my biscotti driver but it loses the moonlight mode. Why? 0.1% mode doesn’t work with more tan 8x7135

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Hum, didn’t know that! Thanks for the info :+1:
Still, mine has lost the ability to change modes. It’s simply stuck on the Highest mode :person_facepalming:
A piece must be damaged for sure…

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Thanks vw :wink: I’ll take that into account when soldering my tips :wink:
So many ways for the same thing is some times confusing, so I’m glad to have people here to help on this :+1:
I guess I’ll have to wait a bit to make my new attempt on stacking as I need new drivers! I may order some spare just in case I fail :smiley:
Thanks again !!

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I deleted that post and was going to make it different. No worries.
the solution was around post #32 on page 2. I’ll just repost the link…

https://budgetlightforum.com/t/-/38827/32

22

When i stack 7135 i prepare them by removing the middle leg and bending the 2 outer legs down.
Then i put a droplet of super glue on to of the present 7135 and put the prepared one on top.
Then i solder the outer legs on to the bottom one.
And then i bend down the big tab so i can solder it to the bottom one with a fairly large amount of solder, so that it has a decent thermal path

I also did this some time ago:
What did you mod today? - #2400 by Jerommel :smiley:

23

Thanks vw!! Hell, this is getting crazier on my head :smiley:
But i’m mixing it all up and then I’ll conclude with the driver, the chips and the iron solder on my hands :nerd_face:
So: ZozzV6 and Jerommel solder the back tab and 2 tips in the front; and on the BD04, besides soldering the back tab, the front pin has to be soldered!

An then Jerommel makes that:!!!: Dude, that’s insane!!! But awesome :smiling_imp:
Did it work? :open_mouth:

Damn, I really have a lot to learn :person_facepalming:

Thanks sharing for your suggestions and experiences! It’s helping a lot :wink: