17mm & 20/26/27mm single-sided DD/FET driver release: A17DD-SO8 / A20DD-SO8 / etc

Since I’d been playing with the layout again for this driver it struck me that what I’d really always wanted was LED+/- pads that were across from each other. IMO that’s a key aspect when it comes to very,very, tight builds. I set about shuffling things around, but they wouldn’t play nicely. Then I recalled that the LFPAK56 footprint I was using sucked. Switching to a normal Power-SO8 footprint helped, but it took me a long time to achieve the level of symmetry I was looking for. Without the OTC it’s actually really easy to do all kinds of great symmetrical patterns (ask me how I know, oops!). In the end this was the best I could do. Now that the signature look of the original driver is entirely gone, I’m not sure whether to call it something else or what.

Also note that I didn’t spruce up the Power-SO8 footprint any for LFPAK56 use. While it should function fine I’ll probably do that at some point.

As far as functioning with the Zener, this should be very similar to v030. (so in theory they both should work fine :p)

Oops, don’t use this one. I made a minor error with the vias & GND ring on top. While this one should work, I recommend v024, v030, or wait for v042.


OSH Park ~

Now moron’s like me can stack the MCU on the MOSFET footprint. :stuck_out_tongue:

That looks nice Wight, dont’ think you should change the name as the Revision number suffices. That’s just me though. I’ll have to get some of these, and solder paste stencils, and give em a go. (starting to get more than I can remember what goes where) I need to use up the ones I have and switch over to these… my memory doesn’t multi-task well.

My zener build of A20DD-SO8 does not work either, normal build works ok.

Put the capacitor under the Zener, that’s supposed to do the trick.

What I don’t know is if it takes a second capacitor or just relocation of the C1.

I’m sure that relocating C1 is sufficient.

Yeah I read about that, but the C1 is half the length of the pads for the zener. Anyway I assume the layout will get fix without the need to make-shift.

I didn’t know if it needed to be there for continuity or if the pads should be jumpered or what. Thought it might be necessary to continue the lineage for the LVP.

Oops, another minor mistake. The WIP v041 version has a problem with the GND vias and GND rings. I’d hold off on that one until I can release v042, although it should function. In the meantime v024 is still fine for single cell builds or Zener w/ the workaround described above and v030 should be OK for Zener builds w/out a workaround.

No, it should be fine with C1 completely unpopulated as long as you’re doing a Zener build and have place the cap for C1 over on the Zener pads with the Zener.

Correct, C1 is not a great fit there. You may also place C1 right next to R2. There is plenty of space to put C1 Against the right-hand end of the Zener and either solder the other end to the GND ring (scrape first) or solder it to the GND side of R2. I’ve just checked to make sure it would work, I was able to solder the cap in there without an issue with the Zener already in place. Adding some extra solder will help. EDIT: be sure not to solder to the other end of R2 (the end pointed towards the middle of the PCB).

All of my first Zener mods had the Zener laying down, embracing the capacitor on a Qlite driver. Can’t see how this one would be any different.

Let me ask this then, if I already have the driver built (I’ve got 9 sitting waiting to be used) and I have need for a Zener modded version…can I add a second capacitor with the Zener? Do I need to remove the C1 from it’s original location?

I think it’s different. When I set a cap on those pads it looks a bit tricky to solder in place. The cap can’t touch both pads at once - the SOD123 pads are too far apart. Your Qlite builds had a 0805 cap sitting on a 0805 pad which is longer than the cap itself. The SOD123 Zener will actually just barely fit on long 0805 pads by itself…

Good question! The answer should be no problem. Add the cap, leave C1 in place, and you should be fine IMO. I’d bench test to be sure though.

Off to test my bench…

I wasn’t going to do it tonight, but my curiosity made me look at it, and from there I was a goner.

Piece of cake. Took a built A17DD-S08, removed the diode, stuck a 200 ohm resistor in it’s place, held the small capacitor between the pads with needle pointed tweezers and touched solder to the pad then the cap, same on the other side… cap in place. Located the Zener for position, laid it on it’s side cupping the cap, badda bing badda boom done!

Soldered on 2 20ga leads, stuck those to a 20mm Noctigon with an MT-G2 on it, soldered by ground lead from my test cell that has a switch soldered to the negative, taped a second cell to it. Fired it up! 5 modes, presto! :bigsmile:

Thanks Guys! Really appreciate it, that was kinda driving me nuts! My last 2 Zener mods I went back to the very first BLF FET boards from matt, out of retaliation. lol

lol, the ones with no GND ring? :evil:

Looks good. Thanks for posting the pic showing how it’s done!

I think making that joint is probably fine for those with enough soldering experience (and a pair of tweezers ;)), but some might find it difficult. The alternative placement I mentioned above also works best with a pair of tweezers, so I don’t know if it’s any easier.

I’ve only been soldering since I got the Hakko 888 station. I used to butcher stuff horribly with a 25 watt Weller iron or an old Sears dual power gun. I sucked, in very ugly ways with cold joints that broke.

So I’ve only really been successful for about 6 or 8 months. Might be close to a year now, don’t remember for sure. I DO remember that switching to the .031 solder helped tremendously even before the Hakko, then getting the right tool made all the difference in the world.

I’ve used a small variety of soldering tools. For years I used a 100W gun for everything (do not do that). I’ve had a 25W and a 40W iron IIRC. I also have an 80W iron for use on big, stubborn things. Eventually I got OK with the 40W I think. Then I got a knock-off temp controlled station. That was an improvement, but after 6 months or so it started having problems and within a year of purchasing the knockoff station I got a Hakko FX-888. I’ve been very pleased with the FX-888.



  • Updated top silk w/ L+/- identifiers & orientation mark for MCU.
  • Updated MOSFET footprint including tstop and tcream. Tcream isn’t perfect but it’s better than the old version (which put down way too much).
  • Updated spring bad on bottom. Main circle is exactly 8mm, the spurs extend to 11mm (for soldering on a 10mm spring). I’m still open to suggestions about what spring sizes people use.
  • Moved the lone via closer to center of board. Via is now w/in 0.5mm of being centered.
  • Updated bottom silk to fit new spring pad.

The via being 0.5mm away from centered is bothering me. I’m aware that I can improve the appearance of the bottom by rotating the spring pad & silkscreen a little more. That will likely happen in a future version.

Seems like moving the OTC to below the Zener should allow that via to be centered. The OTC trace would have to run between pins 7/8 edit 6/7 and the OTC pads would have to straddle the pwm trace but neither of those are untried.