Pretty Purple PCBs :laughing:
Schematic for the DD+1 driver models listed above:
And these two oscilloscope screen grabs show why R5 was added during testing of the initial Q8 driver. With R5 = 0 ohm:
The yellow trace is the power feed of the micro controller at its pin 8.
With R5 = 2.2 ohm (I am using 4.7 ohm now):
Well done :+1:
These finished boards look great.
Oh, by the way thanks for your research of the R5. 
Thanks HQ. Hope you do not mind my appropriation of your HQ4D board
I actually ordered and built a few of your boards, but OSH missed the vias on half of them. So I just added a few of my own design on my next order. Great balance of power and heat in a small light.
Hi Del,
I don’t mind at all. I didn’t invent the wheel with the HQ4D either and just adapted existing ideas for my needs.
Out of curiosity: Which vias were bad and how? I encountered all kinds of oshpark glitches, but til now the vias were nor affected.
They simply missed all of them on some boards. No vias at all. That was my only OSH Park glitch up to now.
I dont understand it at all DEL but do know its good work. :+1:
Wow DEL! That is a bunch of boards! I’d seen a couple of your boards at OSH Park, so I knew you were working on some. But I didn’t know you had this much going on! Impressive! Thanks for sharing these with us!
very clean layouts, good stuff.
It would be nice to update RBD’s Oshpark thread with a link to here.
Thank you, DEL, for all your contributions, research and help. 
That thread is long overdue for a massive update. :person_facepalming: I’m not really sure of the best way to keep its op from getting unwieldy. It’s very difficult not only to edit a single already LARGE post but navigate it to find something. So many drivers only slightly different from each other, not to mention all the other project pcb’s. I’m inclined to just post author thread links under linear, buck, and boost and let the authors organize their own op descriptions and links and accept that there will be a fair amount of redundancy. Given that no one of us has editorial control to organize the separate threads into consistent layout under one umbrella it’s always going to be a patchwork but I need to do at least something to bring it up to date regardless of the result.
Thanks RBD. I do use your thread regularly and assume others do as well.
Nice work. Each new design might seem to add an unnecessary redundancy but to me that’s part of the evolution of the drivers to find out what works best. Having Oshpark available to try them in piecemeal quantities makes for a hand in glove relationship. It’s just difficult to keep track of.
Thanks for the kind words everyone. I hope to eventually add schematics and also scope traces to show the advantages of the few extra components.
Of course if you need an OTC, or would like to have the full complement of stability components on a 17 mm board, or a 3-channel board, TA is your man!
I will add a link on RBD’s thread as requested.
+1
Those who design boards will always make new versions for their needs. Be it a small tweak or a big change. But if it’s shared, those who are not accustomed to board design will benefit from this diversity and the designers get new ideas. I’m always happy to see new designers joining the herd and new designs coming up.
And this, RBD, is where your thread is the center of it all. Be it patchwork or not, it’s invaluable.
Which reminds me I’m overdue with enlisting more than one board to your thread myself. :person_facepalming:
Nice! What do I need to add/change to get it going for a 2S setup?
Have to add a resistor and Zener diode in the same positions as on the ‘standard’ DD drivers. Here we have the luxury of C2. So swap out D1 for a 220 ohm resistor and replace (or stack) C2 with a 4.7 V Zener diode.
The same precautions hold as usual:
- This is only good for 6 V emitters.
- The 7135 will run hot at high PWM, but the 7135 has a good surface of copper for itself on this board and it should be OK.
- Parasitic drain will be up to 20 mA while the tail switch is on.
EDIT: If the voltage reading is important, I would lower R5 to 1 or 2.2 ohm get a more accurate voltage to R1/R2. This is necessary because of that 20 mA parasitic drain.
Great, thank you! Ordered!
The Yezl boards came in on Thursday so I put one together today. Fit is pretty good, just had to take ~0.5 mm off the ears for a nice snug fit.
The Digikey switches will only be in on Monday, so I transplanted the stock switch for now. It had two plastic support pins at the bottom that I was unaware of (snip-snip), otherwise the footprint is identical to the Digikey part number.
Melted the corners of the switch a little with the hot-air rework gun 
…will try some aluminum foil protection next time.
