Today I had time at home with the family away, and was in a bold mood, so I went on building a A17DD-S08 driver, for use in a triple XP-L X6 build. I know Dale has built tons of them but being an electronically challenged person it was quite a task for me (and I failed in the end). Here's the inside story of a clumbsy and chaotic electronics noob, making all kinds of random assumptions leading to wrong decisions:
I had ordered a couple of v024 boards earlier, so then I had to get the parts, which was not easy without spending tons of shipping costs. I got an assortment of resistors and caps from ebay, in the meantime finding out that there is several sizes, and for the first time understanding what the heck '805' meant that pops up in several threads on BLF.
Cereal_Killer had sent me some parts for building a few drivers a few months ago, the nicest was that he sent me some Attiny MCU's on which he programmed my favorite custom UI with off-time mode-switching. From his parts I also used the diode (I know now what SOD23 means), and the 4K7 resistor, the 22K resistor I found in the ebay-assortment. In the meantime I have learned (I had to..) the smd resistor code, and that there is at least two widespread versions of them. Also I looked up again how the polarity of the diode can be found out (the stripe is facing the minus). Unfortunately C_K forgot to add the 4.7 uF cap, and my cap assortment only went up to 1 uF (I used one as off-time cap), so I had to scavenge the C1 from an old NANJG-driver, I picked it up from a 101-AK (
).
I am allowing myself one Mouser order every year, and I wanted some XHP70's for trsting and some Rebels anyway so this was the time, and a good opportunity to order some of those PSMN3R030YLD FETS too, and Zener diodes (it took me half an hour to find a thread on BLF that did not just talk about zener diodes, but also contained a part code for it, thanks Ouchyfoot for asking that same question before) and 200 Ohm resistors (could not remember what those were for).
So now I was sorted, I'm a reflow pro, so the actual placing of the parts and reflow on my heatblock went fast and smooth. The morale here is: information is everything, it took me months of figuring how, and arranging parts, the actual build was 30 minutes.
I soldered an old XM-L2 on a board to the driver and pressed the battery against the driver. It fired up alright, but the mode-switching was all funky as well, something was not right (had to do a random number of half-presses to get to high and when on high, after two seconds I got 3 flashes followed by a output step-down, this all was not what C_K had programmed for me). Then I put the driver back on the heat block and swapped the custom-Attiny with a qlite Attiny. Still weird mode-behaviour. Then I swapped again to the 101-AK Attiny. Still modes were acting weird. I thought that it might have been my scavenged C1 cap since it did not come from the 105C but from the 101-AK, so swapped that to one from a disposed 105C. Still funky mode changing. Then I realised that the off-time cap was still there, so I removed it. Now I got a familiar working driver at least.
I decided to make another of these drivers because perhaps the custom-Attiny was not at fault, but the wrong C1 cap. So I re-used the custom-Attiny and made me another A17DD-S08, with the correct C1-cap. And mode-switching worked smooth on this one. I thought victory!
Encouraged by succes I went on to zener-mod the first driver (with the 101-AK-Attiny) in the workaround way that was tested out for v024 . Lucky for me Dale posted a picture of his build a bit north of this post, because else I would have had put in the zener backwards. I got it soldered in nicely with the cap cosy against the zener (I can solder well) and fired the driver up, nothing. Then I realised that also the diode had to be replaced by a resistor. Hoping that I had not destroyed the driver I replaced it with a 220K resistor (Dale's picture showed 2000 on the resistor, and with my newly acquired knowledge that had to be 200K-Ohm
). Still nothing. Then I decided that I was no good in this and rebuilt the driver to single-li-ion without zener-mod. When the zener was removed, C1-cap in original position, and RVP-diode back in, the driver was dead!!
Still happy with the second driver, I started playing with it, and now it appeared that mode-changing was indeed very smooth, but that in high mode the flashes plus step-down after just 2 seconds was still present in high mode, horrible! I did not test it long enough before on high to notice (test-ledboard was not attached to anything). What I am beginning to think now is that C_K has made some errors in his UI-programming. And also just now I read back in Ouchyfoots thread that the resistor to replace the LVP-diode in the zener-mod should have been 200 Ohm, not 220K (ah, that is why I orderded those :-( ), so it could have worked after all.
The morale of this story is that if you do not have much clue about real electronics and just go ahead with making these drivers, it really is hard, especially if you are a bit chaotic like me! The information is scattered all over the place because folks who really know their stuff (understandably) do not repeat the simple established things all over again (it took me back to a thread from 2010 to finally find out which pin on the ATTiny is pin5, it will be somewhere else as well, but I could not find it).
Sooo, after a whole day and two faulty drivers I'm a little wiser, so the next go at making these drivers will be easier. I may recover one of the drivers with a qlite-Attiny (with no mode-switching unfortunately), but because I will never be able to flash firmware to Attiny's (no windows computer, no skills, afraid of programming software) I am looking for a new source of programmed Attiny's that do allow off-time mode-switching.
BTW, I did make a video of the second reflow, and because I still think that reflowing looks like magic, here it is :-) :