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Thread: Build Log: The 1.5V Project

  1. #1

    Default Build Log: The 1.5V Project

    Hi CPF!

    The intent of this thread is to serve as an ongoing build log for a project I've been working on for a little while now. I always enjoy reading the build logs of others and I firmly believe we can never have too many people documenting their projects (so if you're working on something, post about it so I can follow along!). Hopefully this thread will serve as an interesting read or a cautionary tale, depending on how things go .

    I should mention that this build log will be a little different format than I would normally do. I very much prefer to complete a project, document the whole thing with pictures, and then do a write-up afterwards. It makes for a nice clean post with lots of visuals. In this case though, the scope of the project is much bigger and I'm simply not done! So I'll be adding to it as I go along.

    Enough of that though. Without further ado, let's get down to business!


    The 1.5V Project

    Not much a name, I know - it was the first thing that popped into my head when I sat down with this grand idea. It kind of stuck and now all my documentation is labeled that way, so I'm just going with it. The project started as a wild idea to create a 1xAA light. It's always been my favorite format and I've yet to find the perfect AA light (probably because my definition of perfect is constantly changing). Which is actually part of the reason why I set out to try and make my own; one can never be satisfied until they control all the variables.

    The criteria at the outset of the project was pretty simple:

    • Runs on 1xAA
    • Doesn't need to be very bright, just usable
    • Couple hour runtime
    • MUST use a reflector (I really dislike optics)
    • One fixed output level.... BUT the output level must be programmable through an interface and not by swapping resistors or using trimpots or opening the light
    • Must must MUST have an emitter I like. I don't like the XM-L2 nor am I particularly fond of the Nichia 219. In today's marketplace a light using something other than those is a rare beast
    • A clicky body for clipping to my jeans pocket and a twisty body for riding in the 5th watch pocket
    • NO KNURLING ON THE BODY, just the ends. My lights spend most of their life squeezed between my lips and I hate it when the knurling shreds them all up (especially as we head into winter)

    There ya go! There are no shortage of 1xAA lights on the market and I'm sure if I looked hard enough I could find something to tick all those boxes. That'd make for a pretty boring build log though, so let's pretend this light doesn't exist and we'll make one instead.


    [----- I'm going to update this post as the work progresses. I will add a link to each section below for ease of navigation -----]





    Prototyping the Circuit



    Building the Test Platform



    Pogo Pin Programming



    Solder Stencils (and high blood pressure)



    Writing the Firmware


    Building a Better Socket



    Rolling the Die(s)



    Machining the Driver Pill



    Machining the Head & Body



    A Clip Named Misty



    Punchin' The Numbers



    The Sum of its Parts



    Beamshots and Afterthoughts



    Runtime Graphs
    Mini Update: Needs More Threads!

    Mini Update: Cutting Ahead

    Mini Update: To Trim a Reflector



    I See You've Constructed A New Light...
    Mini Update: Thoughts on v1.2
    Mini Update: Punching a Square Hole



    Quality vs. Quantity



    A Host Does Not a Light Make



    LED's and 003's



    Practice Makes... Diamonds?



    Instruction Manual
    (or: How Do I Work This Thing?!)



    A Dazzling Display of Color



    Instructional Videos



    SOIC Programming



    PCB's Fit for Royalty



    Back to the (Bread)Board



    Now I Know My ADC's



    Machining the Gen. 2 Driver Pill



    Machining the Gen. 2 Head



    Machining the Gen. 2 Tailcap



    Machining the Gen. 2 Body



    Putting It All Together



    15VP v2 Measurements



    3rd 4th Time's the Charm
    Last edited by calipsoii; 09-06-2017 at 09:43 PM.

  2. #2

    Default Re: Build Log: The 1.5V Project

    Prototyping the Circuit

    With a general idea of what I wanted the circuit to do, I set to work reading datasheets and ordering parts. When they arrived a few days later (DigiKey shipping to Canada is amazing!) I was excited to hook them all up. Previous projects have taught me that a little planning can save a lot of headaches though, so I started with that.

    The squares in an engineering draftbook are excellent representations of the solder pads on a chunk of protoboard:


    The wires connecting the microcontroller in the middle are TINY enamel speaker wires. They're about as wide as one of the lines in your thumbprint. So if the soldering looks sloppy, you'll forgive me


    The million dollar question of course is: does it work? Well let's grab a couple batteries (one new L91 and one very dead alkaline)...



    ... and hook them up and see what voltage we get out of it!



    Looks good! It's very gratifying to find out none of your enamel wires are shorting against each other. Added a green LED (Vf = 2.3V) to indicate whether we're cooking with gas when a cell is connected


    In my excitement I couldn't resist hooking up a power LED to see if it worked (probably not a smart idea without some current control but everything survived)


    It's easy to lose sense of scale when looking through a bunch of macro shots, so here's one to give you an idea how bloody small the step-up chip is


    With the boost converter prototyped, it was time to look at the aforementioned

    • current control
    • programmability

    I started with the programmability bit since this is more up my alley. This simple protoboard just has an Atmel programming header and an input and output header. The only way I could get the microcontroller to route its wires nicely was upside down, so it got soldered dead-bug style.


    The uC board was hooked up to my AVR programmer to confirm everything worked (it did - discrete components with large legs are so lovely to solder) and it was time to move on to the current control board. As you can see, the boards are quickly multiplying...


    The prototyping ended shortly after that when I realized that my enamel wires simply would not fit into the 0.4mm pitch of the LED driver. No way, no how was that getting soldered. The end result looked a little bit like the board had been through an autopsy.


    No matter, we've come to far to quit now!

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    Last edited by calipsoii; 10-26-2013 at 07:15 PM.

  3. #3

    Default Re: Build Log: The 1.5V Project

    Building the Test Platform

    When last we left off, I was discovering how amazingly, impossibly small 0.4mm pitch is on a DFN chip. With a box full of Digikey parts mocking me though, I had to know whether this circuit was going to work so it was time to head into Eagle and make a couple real PCB's.

    (I should mention that I asked an electronics engineering grad whether my circuit diagram was going to work. He wrinkled his nose, called the design 'perverted' and said he didn't know. Ah well, only one way to find out.)

    The circuit design in Eagle took 5 weeks. I was 3-for-3 on ordering PCB's and discovering I'd overlooked stupid errors in my design so I spent extra time on this one. When the boards arrived there were no obvious defects.


    Well, almost no defects. I failed to take into account the amount that the router bit would remove as it made the boards circular and it trimmed an excessive amount of my heatsink/ground pad. This ended up being a serious pain in the neck later on, so I figured I'd mention it now.

    Soldering on professional PCB's is a breath of fresh air after working with enamel wire and protoboard. The 2 boards (boost + driver) turned out very nicely and all the little 0.4mm legs reflowed wonderfully in my $55 Black & Decker toaster oven.



    I've found over the years that any time/effort you expend up front on something usually pays dividends later on. With that in mind, I wanted to make the test bed functional, accessible and easy on the eyes. This was the final design; it's about half complete in this image. All the major components (electronic guts, LED, switch, battery) are swappable and easily probed with a multimeter. The wood block is a stained chunk of oak.


    To finish it off, a warm-white Osram GDP gets strapped to the aluminum heatsink and a piece of clear plexiglass pins the driver boards down.


    I whipped up some very alpha firmware and loaded it via the programming header (6 pins in the foreground). The software just displays that the primary/secondary LED's are working and that the LED driver is setting levels properly. I initially set the output to max and the light started flashing rapidly - it took me a minute to realize this was the thermal protection of the LED driver kicking in! The PCB in the foreground seared a mark into my finger when I touched it.


    With the test bed complete it was time to think about how the firmware was going to work!

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    Last edited by calipsoii; 11-18-2013 at 07:46 PM.

  4. #4

    Default Re: Build Log: The 1.5V Project

    Very cool, saving this thread to watch the build!

  5. #5

    Default Re: Build Log: The 1.5V Project

    Yes, I am doing the same. Thank you for posting this as well as future updates! I'm very interested.

  6. #6
    Flashaholic* AnAppleSnail's Avatar
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    Default Re: Build Log: The 1.5V Project

    Amazing to read your methodical progress!
    My biggest light-hog is my camera.

  7. #7
    Flashaholic* Steve K's Avatar
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    Default Re: Build Log: The 1.5V Project

    Looks like fun!

    Having looked around for boost converters that can run off of one AA cell, I have ask.. what boost converter are you using??

  8. #8

    Default Re: Build Log: The 1.5V Project

    Quote Originally Posted by Steve K View Post
    Having looked around for boost converters that can run off of one AA cell, I have ask.. what boost converter are you using??
    Linear's LTC3528. Only comes in DFN package so it's a little fiddly to solder but the chip seems to work nicely. Only thing I'm worried about is that its efficiency at high drive currents doesn't seem amazing. Need to test it more before I pass judgement though.

  9. #9
    Flashaholic* Steve K's Avatar
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    Default Re: Build Log: The 1.5V Project

    hmmm.... I didn't have that part in my list. The datasheet does hint that 200mA is typical for output current with a single cell input. Since it's a voltage regulated boost converter, it's harder to predict what the output current will be when driving a LED. Are you using the voltage limit as a way to limit LED current (i.e. setting the voltage fairly low, such as 2.9v), or are you relying on the mosfet current limit as a way of limiting output current? Or maybe just using a single cell battery is sufficient... it's not easy to get a lot of current to flow through an inductor without much voltage. The inductor resistance might be enough to limit current.

    and while I'm asking questions... I can't help but notice that you have two boards, and both have inductors on them. One board is the boost converter circuit, and the other is for the Atmel uC. Is the Atmel running as a buck converter? That inductor probably isn't on the board just for looks, so it appears that you are running two converters in series. That's not going to do much for efficiency. Or is the boost converter just to provide power for the Atmel, and it's running as a boost converter to drive the LED??

    If you could post a schematic, that would answer a lot of questions!

    oh, for what it's worth, I found a nifty boost converter designed to run a high power LED from a single AA cell. It's the PAM2805 from Diodes Inc. It appears to be designed specifically for flashlight use. The only problem is that it doesn't appear to be available in small quantities right now.

  10. #10

    Default Re: Build Log: The 1.5V Project

    Hah, no way I'm posting a schematic Steve K. Then you'd know exactly how little electronics education I actually have. Sort of like finding code I wrote 10 years ago - it did the job for 10 straight years, but man, it sure ain't pretty. I have a little mucking around to do but I have a feeling I'm going to lose the 2nd inductor. It was an experiment that hasn't worked all that well so far. Assuming I can coax the thing into doing what I want I'll post more details later!

    Right now my big problem is heat - wood is an excellent insulator! A nice-looking choice but probably not the ideal one when ratcheting up the current flow.

  11. #11

    Default Re: Build Log: The 1.5V Project

    Very cool build idea! I can't wait for the next update.

  12. #12
    *Flashaholic* gunga's Avatar
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    Default Build Log: The 1.5V Project

    While I don't have the same design criteria as you, I think this is fine work. Very cool to design and build your own light! Kudos, a fellow Canadian too eh?!

  13. #13
    Enlightened
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    Default Re: Build Log: The 1.5V Project

    Quote Originally Posted by calipsoii View Post
    Right now my big problem is heat - wood is an excellent insulator! A nice-looking choice but probably not the ideal one when ratcheting up the current flow.
    Subscribed! I love seeing real world driver build ups.

    I don't see any vias for the LTC 3528 power pad? so, no associated bottom side copper? Linear fails to mention how much copper area is required to meet the data sheet results. Looks like a 17mm board, so have you tried it in a P60 (or ?) pill for extra heat sinking?

  14. #14

    Default Re: Build Log: The 1.5V Project

    Sorry for the lack of replies guys, work's been pretty busy this week. Gotta finance this hobby somehow!

    Quote Originally Posted by gunga View Post
    While I don't have the same design criteria as you, I think this is fine work. Very cool to design and build your own light! Kudos, a fellow Canadian too eh?!
    Yessir, from smack-dab in the middle of Alberta! Well, even if the design doesn't interest you, I hope I can entertain you in the process.

    Quote Originally Posted by nickelflipper View Post
    Looks like a 17mm board, so have you tried it in a P60 (or ?) pill for extra heat sinking?
    Oh man, if it was 17mm diameter I'd be able to have a huge grounding/heatsink ring around the driver board. I wish! Everything barely fit at the size it is now.


    You're absolutely correct about the lack of heatsinking nickelflipper. Aside from the bit of copper on the board, there is no place for it to go right now. I hope to rectify that this weekend, assuming all goes according to plan. Wish me luck!

  15. #15

    Default Re: Build Log: The 1.5V Project

    Wow, nice work. I can't believe you successfully hand soldered that DFN package.

    Have you tried prototyping with homemade PCB's? I've found that it works well enough that you typically don't have to order professional boards.

  16. #16

    Default Re: Build Log: The 1.5V Project

    Spent a few hours today turning this:


    Into this:


    A little rough around the edges, but pretty damn good for a first attempt at a prototype I think! There are pictures of the machining process, of course, but I do need to save something for my "Building the Pill" chapter.

    I think that this should help immensely with dissipating the heat from my test boards so I can finish writing the firmware. They fit snug as a glove. There is a threaded slot on the side for a tiny hex head set screw but nobody in town carries them so I'm waiting for an internet order. It'll tighten the pill up so things don't bounce around.




    Going to solder components on those 2 boards tomorrow and see if that helps with the heat!

    Quote Originally Posted by Mike S View Post
    Have you tried prototyping with homemade PCB's? I've found that it works well enough that you typically don't have to order professional boards.
    Hi Mike S!

    I have actually done a little etching at home:


    There's no way on Earth I could etch a 0.4mm pitch DFN footprint though. I basically consider having the PCB's professionally done the cost of my sanity.

  17. #17
    Flashaholic* John_Galt's Avatar
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    Default Re: Build Log: The 1.5V Project

    Very interesting build!

    Looking forward to some updates but I have a few questions about the overall circuit design.

    -you built this to use a 1.5v powersource. What changes would be necessary to have the same functionality from a 3v source? I have several older lights that ive been looking to upgrade (arc ls, longbow micra, etc)
    -what is the maximum and minimum drive levels currently? And what sort of efficiency are you looking at at each?
    -im sure this will be detailed, but what sort of ui are you looking at?
    I love my HDS/Ra Clicky... My only wish would be a 5th(accessible thru a 2click press) mode, and a 2AA tube.

  18. #18
    Flashaholic* John_Galt's Avatar
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    Default Re: Build Log: The 1.5V Project

    Very interesting build!

    Looking forward to some updates but I have a few questions about the overall circuit design.

    -you built this to use a 1.5v powersource. What changes would be necessary to have the same functionality from a 3v source? I have several older lights that ive been looking to upgrade (arc ls, longbow micra, etc)
    -what is the maximum and minimum drive levels currently? And what sort of efficiency are you looking at at each?
    -im sure this will be detailed, but what sort of ui are you looking at?
    I love my HDS/Ra Clicky... My only wish would be a 5th(accessible thru a 2click press) mode, and a 2AA tube.

  19. #19
    Flashaholic* Hallis's Avatar
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    Default Re: Build Log: The 1.5V Project

    amazing work. Can't wait to see the pill build. Might want one of these little things for myself as i've got a 1aa mod that I used to have a LuxIII/14500 setup in.
    -Shane
    Looking for customer Surefire E series custom components by McGizmo, Leef, Balrog, etc. Also looking for Mr Bulk lights and Fivemega Mag Mods / Elephant. PM me

  20. #20

    Default Re: Build Log: The 1.5V Project

    Danged nice work!! I like the thought put into the project.... even the test platform is almost surgical!!! Nice!! Anxious to see more. Dan.

  21. #21
    *Flashaholic* Illum's Avatar
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    Default Re: Build Log: The 1.5V Project




    subscribed!

  22. #22

    Default Re: Build Log: The 1.5V Project

    Pogo Pin Programming

    When it came time to test the lower/upper limits of the firmware I ran into an instant and serious thermal issue. The wooden test platform was horrible at distributing heat away from the driver PCB and thermal shutdown meant it would run on high for < 1 second before turning off. It became apparent that the driver boards needed some heatsinking to really test the efficiency at high drive levels.

    A few hours (ok, a full day) on the lathe later and I had a brass pill:


    And it fit the boards really well!


    For this board there wouldn't be 6 wires coming out of the pill so I needed a way to program the board in-place. With a bag of pogo pins, it was time to make a programming header.

    I started by marking out the holes on a sacrificial PCB:


    Then chucking up a 1/64" needle-thin drill in the Dremel-press:




    The results weren't very pretty... I think my punch marks were off-center which caused the drill bit to wander around before biting in.


    I repeated the same thing, but with a pin to hopefully get the punch marks closer to center:




    Most of these holes went in dead-on. I realized while test-fitting the pogo pins that they were simply too wide to squeeze 6 of them into such a small grouping without shorting them together. The 6-pin header quickly became a 1 pin header as I drilled holes in pads all over the place.


    I applied a little electrical tape to the bottom of the board so the pins wouldn't touch any pads or traces, then poked them through and (messily) soldered them in place.




    Six wires were run to a remote programming header and the messy little device was finished!


    In use, the programming header is placed over top of the board to be programmed, then pressed down. The spring-loaded contacts maintain pressure while the code is banged over the wires into the device. The pins are only 2mm in diameter but look huge in comparison to the PCB pads. No wonder they wouldn't all fit!


    With the code sent, I attached a few wires, squished it all into the brass can, and fired it up!


    The secondary LED sprang to life....

    ... and proceeded to flash error codes out at me. The microcontroller wasn't communicating with the LED driver. A bad solder joint and the whole assembly is now basically useless.

    Soldering the LED driver has been hell on this project. It's a 0.4mm pitch DFN package which means it's 3mm across and has 6 legs half the width of a human hair that all need solder and cannot touch each other. Oh and there's no way to tell if they're grounding beneath the package because you can't see under it.

    My current method of reflowing standard solder just wasn't working. It was time to give solder paste a try.

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    Last edited by calipsoii; 11-18-2013 at 09:07 PM.

  23. #23
    *Flashaholic* gunga's Avatar
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    Default Build Log: The 1.5V Project

    Wow. This is pretty darn cool. Even when things don't work it's cool to see.

  24. #24

    Default Re: Build Log: The 1.5V Project

    Solder Stencils (and high blood pressure)

    I've never used solder paste before, mainly because:

    • It must be shipped overnight in a refrigerated container
    • It costs almost $1 per gram
    • It's basically liquid lead that goes everywhere

    The idea with solder paste is simple - you make a stencil and squeegee it on (like silk-screening a shirt). Then you plop your components in the paste and bake at 240. Soldering without the iron! Stainless steel solder stencils from overseas are $100+ dollars. Mylar ones are $10 but shipping to Canada takes 3 weeks. I had neither and wasn't willing to wait a month and spend a couple hundred bucks until I knew the stencils would work.

    Enter Felix! DIY home-made SMT metal stencil - the definitive tutorial. His video made the process seem pretty simple. I'll spoil it for you and tell you it's not.

    I started as he did - by chopping up a soda can.


    He recommended cheap shelf vinyl so I went and bought some and tested my laser printer out on it...


    ... and tested, and tested, and tested. Every possible combination of printer settings was tried until I found the sharpest image.


    A hot iron was then used to transfer all the laser toner off the vinyl and onto the aluminum:


    Or.... not?


    Boy, that didn't come off on the metal even CLOSE to how it appeared when printed:


    An entire day disappeared while I tried different iron temperatures/time/pressures. 6 hours of ironing and this was about as good as it was getting.


    Getting rather desperate (and increasingly frustrated ) I decided to switch from Felix's vinyl recommendation. When I etch copper boards I use magazines for toner transfer, so I pulled out the nearest, cheapest volume and printed on that instead.


    The difference was immediate.


    As it turned out, that stencil was a fluke. The next magazine stencil came out like this:


    I ironed well over 150 stencils that weekend, going through sheet-after-sheet of magazine paper and getting random results.


    The answer came to me while walking the dog, strangely enough. I sanded the crap out of one of the aluminum sheets and confirmed my suspicion that Felix's "it needs to have a glass smooth surface" idea was bogus.


    The 11 best (now sanded) stencils were selected:


    Each was entombed in packing tape to seal the aluminum from the acid etchant. Only the toner and exposed metal pads were left.


    The etchant was a solution of 1:3 hydrochloric acid to hydrogen peroxide. Definitely not an indoor activity. The glass bowl on the right has the solution and the plastic one in the middle was for rinsing.


    The etching took about 9 minutes in the -5 celcius weather. It starts quite slow and finishes extraordinarily fast.


    Pulling it out of the bath, I wasn't exactly blown away. Looked like nothing at all had happened - until I flipped it over against the sun.




    Three at once was a horrible idea; I couldn't get them all out and rinsed in time and a couple over-etched.


    With the etching done, the tape came off and the acetone came out to remove the toner.


    The stencil needs a jig to hold the board in place and give a level surface. This was my best shot at that. The stencil is taped on the left and flips down.


    At this point I was done ironing and etching for a couple (dozen) years. If it works, cool, and if not, at least it looks pretty.


    While it's probably not any more harmful than solder you hold between your fingers, this stuff gives me the willies.


    A little bit goes on the stencil...


    ... the high-tech squeegee comes out...


    ...


    My second attempt did better. Each subsequent attempt actually improved quite a bit.


    There are 4 legs on that chip in the middle - not 2. The legs got bridged and this board is useless (I couldn't fix it with my iron, no matter how I tried).


    Unfortunately, my first 14 attempts all came out with 2 legs due to solder bridging.

    The 15th worked.



    The DFN chip was even worse - it would look perfect but fail to work for no obvious reason. Pulling out the multimeter would inevitably tell me that it was bridging beneath the chip where I couldn't see it. I really needed a way to test whether a solder job had worked successfully without populating the board and finding out afterwards.

    This is about the point where I realized after 35 scrap boards it was time to work smarter, not harder, on this project. It was also time to take a break from it; for my sanity, my pocketbook and my marriage. For the next month or so I'm going to think about what I want my diagnostic board to do (flash firmware, test electrical connectivity, etc) and then make a proper one.

    Should be back with an update then!

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    Last edited by calipsoii; 01-23-2014 at 09:33 PM.

  25. #25
    Flashaholic* Hallis's Avatar
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    Default Re: Build Log: The 1.5V Project

    Wow I couldn't even fathom soldering things that tiny. This may or may not help but it just popped into my head. Some companies do brass photo etchings for detail sets for plastic model kits. Some of their stuff for 1/700 scale warships for example, are impossibly tiny and yet full of details. You might google up some of those and see if they'd be willing to offer you some advice or help. I woudln't be at all surprised if one of them offered to do a little test piece for you to see if you could use it as a stencil and get greater detail with that method.
    -Shane
    Looking for customer Surefire E series custom components by McGizmo, Leef, Balrog, etc. Also looking for Mr Bulk lights and Fivemega Mag Mods / Elephant. PM me

  26. #26
    Enlightened
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    Default Re: Build Log: The 1.5V Project

    calipsoii I have felt your pain in working with a LTC3454 DFN package (a whopping .5mm lead spacing), and no stencil. A shelved project, but when revisited I will be going with an OSH Stencil to keep my sanity. Being in the States, their stencil turnaround is about a week.

    Also tried the pogo pin to blank pad programming interface, and wasn't impressed with that method either. My best results were to make an adapter from 0.1" spacing male header and wiring to another adapter with 0.05" spacing, and corresponding pads with a minimum annular ring to match, like this:

    That was for a PIC on a bigger board, but I'm sure Harwin or? has 2x3 headers with 0.05" spacing. The 0.05" protoboard was a leftover from a piece of SchmartBoard.

    Without vias under the powerpad, and more associated copper, I would be surprised that the project would not have to be derated to some degree.

    Good luck with the project, and thanks for sharing.

  27. #27

    Default Re: Build Log: The 1.5V Project

    Nice work, I wish there were more members DIY'ing their own drivers.

    You might find it easier switching to the photo resist method for home made PCB's and solder stencils. The only downside is that it's more expensive, but I can say from experience that it's worth the trouble. You'll be able to etch a 0.5mm pitch with sharp professional edges, no problemo.

  28. #28
    Enlightened
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    Default Re: Build Log: The 1.5V Project

    Did you try solder wick to clean up the bridges? I find that wick + flux works really really well. Also, for such a small board, instead of making a stencil, I buy the paste in syringes and dispense by hand. Less painful :-)

  29. #29

    Default Re: Build Log: The 1.5V Project

    @Mike S
    I'll have to give the photo resist method a try, that sounds much easier.

    @Lyndon
    Yeah I realized afterwards that a syringe would have made more sense. Thanks for the advice about the wick + flux - I've always had really poor luck trying to use a solder wick but I betcha it's because I haven't been using much (actually any) flux while doing so.

  30. #30

    Default Re: Build Log: The 1.5V Project

    I had a chance this weekend to work on the 2nd part of the driver assembly (the sleeve):


    The pill itself slips into this sleeve, which will eventually be threaded and have the head & body screw onto it. I screwed up the drilling and as a result the o-ring grooves are offset (they should actually be centered in the middle). It doesn't matter though since this is just to heatsink the LED and driver for my testing.


    Eventually I plan to use 16mm SinkPads, but in the meantime, this Nichia 119 on a square MCPCB is the only thing that would fit. The grey stuff is Arctic Silver 5 thermal paste.


    This particular driver assembly has the secondary LED soldered right on the PCB so it's currently trapped in the middle of the pill! You can see it glowing through the wire holes. Eventually it'll be moved somewhere a little more visible.


    And it even lights up.



    Quote Originally Posted by John_Galt View Post
    -you built this to use a 1.5v powersource. What changes would be necessary to have the same functionality from a 3v source? I have several older lights that ive been looking to upgrade (arc ls, longbow micra, etc)
    -what is the maximum and minimum drive levels currently? And what sort of efficiency are you looking at at each?
    I meant to answer this earlier John_Galt but wasn't able to get any decent testing done on the wooden testbed. Now that I have some metal to heatsink the whole assembly I'm going to run through some tests and get an idea of how the circuit performs.

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