comfy - no sweat really, like wight said. Just interesting in pt of history - could be they used 10 uF caps early on. 10 uF caps are so well proven, I’d feel it would be risky to experiment with lower values, unless it’s a major re-design as wight is doing, of course.
Just fyi, I’ve measured 10’s, 1’s, and 0.1’s uF caps with 2 different DMM’s (Fluke and advanced model UNI-T) and they all measure slightly lower, but pretty consistent in the range, clearly identifiable.
I had no intention to point a finger at someone and I always saw it as minor details - which it probably still is.
The reason I brought it up now and here is that you all thankfully invest a lot of time and effort and I wanted to avoid that you - unknowingly - might use different components and have strange results, be it at the FET, at the OTC or while adapting firmware. I can’t help otherwise with these drivers but I follow with interest.
Alex - didn't look carefully at your v030 til now. Wow, impressive all that fits! Ohhh - is that a MCU pin #3 pad connected, but covered up? I'm really not lik'n soldering a thin wire to pin #3 directly on the v009's for a locator /LVP LED. Looks like I could just scrape off the covering of the pad?
Edit: Debating whether I should order these 030's now or wait til some testing is done. Not sure I followed everything, but have you been able to breadboard/proto/test this out somehow?
See post #352 above.
FWIW, Dale has parts for a few v030s on the way and we’re going to try to experiment to figure out what value resistors and such work best. I assume the OTC resistor, at least, will need some tweaking. Maybe other parts too.
However, feel free to do your own experimenting. It’ll probably be faster if you do it since the hardware and software parts of your brain don’t have to use email to talk to each other. 
Hhmmmm. I can probably get most parts from here @work, but not sure yet. I looked more carefully at Alex's tests in port #352 (thanks David, my bad!).
K, I'm a little confused, got some Q's:
- this should handle high PWM rates, like 15K?
- looks like there's ringing on the (2) line. Is that because of long LED wires or something else? Is that a bad thing or good/ok?
I'll just go ahead and order boards - $2.20 is no problem at all - feel like I'm ripping them off anyways... I'll be testing on an 85 and not interesting in OTC.
Oops, sorry I didn’t reply Tom E - I saw your post earlier and meant to. :-x
- As far as PWM, this is no different from earlier revisions. Were there any particular changes or comments that brought on the question?
- The ringing is on BAT+. I suppose that it’s due to inductance in the battery/LED wires?
- I agree, every time I order a 17mm or less board I feel like I’m getting a steal from OSH Park. Hopefully we serve some useful function for them!
OK, apparently what I have on hand isn’t that powerful! I hooked up the only triple PCB I have, which is a triple XP-G2. I used it with the highest drain cell I have, a heavily used Samsung INR18650-15M. This setup was only good for 10.3 amps as measured with a clamp meter.
That said, I produced a couple of scope images and played around a bit. These shots are in a low mode, I failed to take pictures of medium modes.
This is the same driver build from post #352 but with some wiring changes (in addition to the LED change):
- I changed the battery wiring to ~200mm total of 18awg.
- I changed the LED wiring to the 22awg included with the triple.
- I soldered on new test points for the scope probes.
Channel order is
- BAT+ from spring side of driver.
- MCU VCC measured at C1.
- FET Gate measured at gate pin.
We can see that MCU VCC reached a safe-for-the-MCU 5v which is nonetheless very high considering that it’s attached to a 4.3v zener with no load resistor! I speculate that the Zener may die an early death like this. We’ll have to try and figure out the peak and average current it’s seeing. Gate looks pretty clean to me, with a bit of badness on the turn-off that we can probably clear up with the pulldown resistor. BAT+ reaches crazy high voltages. The second shot is on a 2v/div scale and shows a crazy high B+ spike of 8v from a single cell! This spike did get a volt or two worse in medium modes.
I’ll see about adding a gate pulldown resistor and testing with that.
When I’ve done realtime voltage monitoring on a FET-only board (Ferrero Rocher), I’ve gotten pretty big variability on voltage depending on the exact timing of the ADC reading. For a realtime display it’s actually not such a bad thing, since it makes the indicator flicker at a varying rate according to voltage. So, it actually provides more of a fine-grained indicator due to the spikes being out of phase with the measurements.
This also affects LVP, but it’s not usually an issue because LVP uses a heavy lowpass filter and because the spikes aren’t very big at low voltage.
For non-realtime displays it works well to shut off the emitter, wait a short while, then take and average some measurements.
I think the only worrisome impact of the spikes is whether it might damage or reset driver components. The MCU actually does pretty well dealing with the spikes as long as they’re not high enough to cause a reset.
If we go with Halo’s idea to eliminate the voltage measurement pin (and voltage divider parts) in favor of the VCC/Vref method, the VCC spikes may become more meaningful to the MCU. I give it only a 50/50 chance of mattering though, for the same reasons the non-fatal spikes don’t matter much on current designs.
The BAT+ spike looks a little scary. I wonder if that could damage the emitters over time. Dale has mentioned that some of his lights don’t measure up to their original performance any more, and this might explain why.
While the B+ spikes may certainly be doing something bad to the LED, I’d say that other factors probably weigh in more heavily. Dale’s shown that things such as batteries, bypasses, clean lenses, etc can have big effects. With all that ruled out my vote is on the heavy currents put into the LED: the LED has thermal resistance between the die and the thermal pad and there’s no getting away from it. More heat will result in an elevated die temp which I suspect will degrade the LED much more quickly than at Cree’s maximum currents. That said, I certainly don’t know. I’d love to eliminate as much bad behavior as possible, including the voltage spike on B+.
This PCB (v030) is not compatible with Halo’s idea. Click through and take a close look at the first graph since it’s easier to read. Each division is 1 volt and zero is 1 division above the bottom (where the little yellow/orange tags are). In post #365 the MCU trace is aqua colored. Note that Halo’s idea is to determine MCU VCC, but as we can see MCU VCC is never similar to B+ voltage. Instead, VCC starts at ~4v and then bounces up to 5v and tapers back off.
I’m impressed with DEL’s results from post #648 here and plan to try out an RC snubber.
I implemented an RC snubber using 10nF and 4.7ohms and got similar results to those DEL showed: ringing was removed but the peak voltage on B+ remained pretty similar.
Maybe try a freewheeling diode next?
Try the two-10uF setup, one before & one after D1. That helps with the bounce at B, and also allows a tiny bit of boosting at Vcc (but with B flatter, the boosting is kept below critical levels).
Well, I built a v009 today to install into a light I need to get rid of… and sure enough I ran into the “bright flash” issue you’ve been talking about Tom E. I didn’t do any measurements - I just installed a 0803 12k resistor as a gate pulldown (as you suggested). Problem solved. Thanks!
Yes, it’s just an idea for potential future use. It might be nice to get rid of the need for the voltage divider, assuming the idea would work as intended. It would only work on 1-cell lights, and only on tiny25/45/85, but if those limitations are okay it might free up a little board space for other things.
Gotcha, just wanted to make sure we were on the same page.
(quoted a bit out of order ) Bad news! I think that v030 should be usable for myself / DB Custom / Tom E… but I did make a mistake and forget about it when those two asked whether the boards were usable. I forgot to hook the 7135 up to LED-.
I reflashed my own built-up v030 board several times before the problem occurred to me. I just couldn’t get moon to light up at all…. of course not, it was on the 7135! I bridged the connection with a small piece of solid wire from a component lead and it works fine. The good news is that the stencils won’t change for v031, no pads have moved.
Here is v031: OSH Park ~
Other topic: I do plan to revamp the spring side again. The current spring pads don’t seem to be a good match for the springs I’ve got. I’m open to input on spring sizes! Scraping’s always an option, but I’d like to accommodate 2-3 common sizes. My initial thought is [Nanjg-105 size], [common medium springs like the gold plated ones from MTN/Intl-Outdoor & the cheap Phosphor Bronze ones from Simon/etc], [big size? Like the ones djozz had made?].
And R1/R2 are still labeled in reverse?
Crap, yes.
Thanks Sharpie!
- It could, but I’m trying to avoid stacking. (I definitely don’t see any space savings from setting them side by side.)
- Correct, I see in retrospect that I wasn’t clear - those were simply the parts I had available. Having so many wrong-size parts made it very difficult to assemble, but they were available and I didn’t have the right stuff. I didn’t purchase any new components for this build. My intention was to use something more common like 5.1v, although I was concerned once I saw how high the 4.3v Zener was able to spike. Maybe the load resistor will help - there wasn’t really enough physical space to install a load resistor in that build and test it out (due to the 0805 and SOD-123 stuff).
- Yes, I agree about parts of this suggestion. A fresh component footprint would help with locating the part while soldering, but that’s about it. Locating the part better while soldering is definitely worthwhile and a new footprint is on my list. The full footprint won’t help a bit with the rest, but that’s OK…
- I suspect that this PCB is quite a bit tighter than you may realize. Sorry that I have not posted pictures of the build and I’ve moved the only driver I built into a light now. Considering that the intention is to operate at high currents a small solder pad won’t really do the trick. My current recommendation for using a brass post is to drop your wire down and solder it onto the top of the brass post, exposed through the large 3mm via. I don’t see why this wouldn’t work fine. Since I also sometimes use brass posts I’ll try and give it a try. With that said, let’s put a pin in the topic of ’LED+ solder pad’ for the moment. If you’ll look at my other layouts you’ll see that I always strive to include good solder pads where possible. Unfortunately due to the nature of these tiny boards we just can’t have everything all at once. Once this board is tuned up maybe a different one will support a decent pad. Or maybe we’ll save enough space to do it here in the end. It’s at the bottom of the list for the moment though. 8-|
- Soldering the LED+ wire into a via is not the way to get the lowest resistance (that’s why we have a bypass hole!). A wire with 2mm jacket won’t fit in the suggested location and would block popular Pomona clip.
- I’m afraid that this will interfere with larger B+ springs. (Take a look at the Gerbers from OSH Park if you haven’t - you’ll see what I mean.) We can check measurements to confirm that, but for LED- wiring at least I don’t see an advantage to through-hole. As far as drilling out to isolate… I’ve often suggested a lot of scraping for various niche applications (or even some more common ones :
(lesson learned) - if there’s no good reason to add drilling I’ll do my best to avoid it. - That’s a topic I’ve been trying to get a handle on. I’d love some insight into choosing the freewheeling diode. I read and understood your post about it needing to be located at the driver in order to operate properly (at all!), but as far as component selection I’m pretty far out at sea. Could you suggest some likely candidates and explain why they are good choices? Or link to some good reading material which isn’t too high-level?
RE:PS: That sounds interesting. I was planning on trying 100nF, but not because I understood what would make it better. 
Could you help me understand why reducing C1 from 1uF to 100nF would be beneficial?
As far as not shorting R3 - I agree. Personally my plan was to put a value of 10R in place and then measure voltage drop with the scope to get an idea of what was going on in terms of current. Clearly it’s going to be a really spiky…
RE:PPS: OK, sounds like a plan to me. Can you think of any disadvantage of increasing the values of the voltage divider by 10x or more? Frankly I’m currently focused on the other stuff and may not jump on that part right away. Hopefully some other members will start playing before I do.
I have solder paste masks and boards should be here tomorrow or the next day.
For sake of the argument, I re-built my Jax X6 Hunter tonight with a new MT-G2 on a 25mm MaxToch copper mcpcb. With brand new Basen 26650’s (came in today) it pulls 11.50A at the tail and makes a whopping 4571 lumens from the big die! And the hot spot is surprisingly tight, probably the tightest yet from an MT-G2 and I’ve got 12 now. (the BTU Shocker only counts as one, although it has triple 9V MT-G2 emitters, worthy of note due to it’s single A17DD-S08 Zener modified driver making 10,000 lumens. My other BTU Shocker uses a like driver to triple XHP-70’s for up to 20,000 lumens in one brief test. So yes, the large via for through board direct positive can be a HUGE deal!)
18 Ga Turnigy leads, I had to use extension tabs off the 25mm mcpcb to allow the reflector to sit flat down on the surface, this after having previously cut the reflector’s aperture square to encompass the big substrate.
Using an older 2 sided driver, big Vishay 07N02 FET piggybacked onto the original 22mm stripped driver board. Power, it’s all about Power!
Oh No! Went to check my order status for the v030's, and there was none - forgot to order them 
. Good news is I can order the v031's, or should I wait on v032's?
Dale (off topic a bit) - how do you like the Basen cells? At first, I saw them beat the EFEST 4200's, but since then, measured in different lights and see the EFEST's beat'n the Basen's, but still head to head in 1-2 lights... It's all very confusing, then again, I'm only looking at tail amps via a clamp meter and not comparing @start and @30 secs lumens measurements, and we know slight amps differences don't mean the same for output.
Still love the Basen cells. My measured all 4500-4600 capacity at 1A discharge, but read someone else posted bout 4100 mAh tested.
Best cell I ever tested in a single cell DD FET setup? Ok, believe it or not, a TrustFire! Well, the TF 32650 that I stripped off it's PCB board of - got 0.5A more then the closest EFEST 4200 in a modded BLF SD10 (Lumintop) - incredible, to say the least...
That Shocker mods sound fantastic! My super high output light candidate will be the 16X XM-L2 bought here: http://www.ebay.ca/itm/121641867876, paid $94 shipped w/XM-L2 CW's. Did a pathetic 4K lumens stock, got it up to 6.8K now with resistor modding and heavier LED wires, spring bypass's. Plan is LDO 20mm FET+1 driver running an 85 w/Narsil, adding SMD LED's for LoBatt/Locator functions. Mainly went with this light for lots of LED's, 6 18650 cells (perfect for Sam 30Q BT's) for 8.4v, and a bighead diameter (99 mm) for better heat sinking and spacing to lay out and fit 16mm Noctigons. Will have to get a custom copper LED shelf built though. It's the same light as this: fasttech-SkyRay-S88 but with XM-L2's. Hoping for 15K to 20K lumens, with maybe a few mins runtime 
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