Musings on the FET+1 and lighted tailcap.

Flashlight Modding and DIY Parts
18

Man PD, you are keeping us in the dark ages . I much prefer e-switch lights - navigating more that 3 modes on a clicky is a PIA, and no matter what many say, just can't get any of my clicky lights with Bistro or the BLF A6 firmware to consistently handle the long hold correctly - every one I have varies with temperature, whether it's a BLF A6 or the BLF X5/X6 v2's. e-switch timing is precise and reliable every time on a 85, and most side switch's, even on $10 budget lights, are much easier to operate than a clicky. Just about any feature in the $40-$120 brand name lights can be implemented.

Do you mean dual e-switch's or e-switch and clicky switch combo? Probably should take this to pm's or another thread, but I have e-switch and clicky support in one firmware version w/limitations. If you want 2 e-switch's, should be easy to add to what I have. Pm me or refer me to another thread - seem to recall you raising this issue, but all depends on exactly what features you want from the dual switch's, and if I can get my hands on a light/host that has that capability. I'm using my Narsil firmware now with a LED ON/OFF control on pin #3 for a locator light and low battery indicator, but could also configure it for a 2nd switch easy enough -- devil is in the details of the required functionality. I'm very interested in a dual e-switch but don't have one, or know of one worth buying that I know is modd-able, budget preferably. I'd love to be able to add my own e-switch's but lack the knowledge or maybe skill set/tools to accomplish that. I've seen lots of mods posted with adding switch's but not enough details, or lacking a lathe or mill for me to reproduce it. Ideally 2 e-switch's is a great setup, if you want one as ON/OFF, or one dedicate to blinkies/bike modes, etc. - lots of possibilities.

19

Beware the wrath of wizards, I believe they say?

But — in every field I’ve ever fiddled in — amateurs and hobbyists make Rube Goldberg contraptions, trying for a desired result.
There’s often a useful lesson in observing the result (because a contraption says what’s wanted clearer than any wishlist can)

Once the idea is clear, the expert might well start from scratch rather than fixing the contraption.

Sometimes, though, the contraption produces worthwhile surprises you wouldn’t imagine otherwise.

‘Do not meddle in the affairs of Wizards — It makes them soggy and hard to light.’

20

It seems that the kettle, upon being called black, has responded in turn. Unfortunately the pot wasn’t prepared for this, and has boiled over.

21

I really tried but I don’t even know if my thoughts are making sense so I let it go for now. Maybe I can re-read again a few times later to make more sense of it.

Thank you sharpie for bringing attention to the matter, I don’t know why others are spamming what could be a very informative thread where new improvements could be made with drama when they have nothing to contribute nor do they attempt to understand the context of the subject matter. (wight excluded as I don’t see his posts as derrogative meaningless spam, but possibly a lack of communication via impersonal internet pixels) It really just puts a bind on a guys like me flipping back and forth sifting through their trash to find the information I need.

I am looking to keep it simple, so I will order a couple old revision 2 led 2 resistor pcb’s in hopes that I might someday actually do something useful, that works properly.

I’m so out of my league here. I have to try, rather fail than give up.

Your saying that I (we) need to know the resistance in the tailcap (overall regaurdless of led selection and quantity) to know what value resistors will need used in place of R1/R2 |OR| which value 1/8W resistor needs jumped from positive spring to ground ring on the battery side?

I have tried a few different resistors on the spring side, lately I have been stacking on C1 but either way it is the same deal with mode switching when hot, so I think swapping R1/R2 would be the ideal way to go about it.

So if I was to change resistor values for R1 and R2 it could potentially bleed enough current to match the needs of the tailcap leds, and at the same time work as a voltage divider for the MCU?

What I am thinking you are saying is that we need to bleed off, as close as possible, the same amount of current that the leds need to stay lit, so the power is being used and not backfed into the caps/mcu causing malfunctions?

Let’s say I am using these leds:
http://www.digikey.com/product-detail/en/150080BS75000/732-4982-1-ND

With a Vf of 3.2V, > and looking to run these leds at .08 mA < subjective, rated 145mcd@20mA.

12,500 ohms total

I am lost.

MattLward
“Oh, I like where this discussion is going. I have been going back and studying basic electronics, have not had to since university in about 1985. I like the PFET idea, but I am not sure there will be enough room on a 17mm driver. Please continue to explore away.”

There is a couple MM height in most pills we could take advantage of. If there is room for traces on the board it could be possible to eliminate the heat tab trace since it’s already connected through pins, and stack a pFET 180* on top of another component bending the legs, you’d have to use a to-220 package or something with legs.

22

Zoom, Sharpie seems like a pretty sharp guy, I’ve said as much in several threads. I think we all appreciate his input.

That being said, I can’t imagine I’m the only one who finds his tone unpleasant.

I look forward to the driver Sharpie designs, and I mean that. In the meantime I hope he cools his jets just a bit so we can have a discussion that doesn’t involve derisive and condescending comments.

23

sixty545 have already done that and mentioned in #178 How To Build a Flashlight With Perfect Modes (picture heavy)

24

I do think that a simple RC network would give much more control over the discharge of the OTC, now it is possible that discharge issues due to lack of direct grounding could be part of the issue. When I first started building and looking at drivers I assumed there was a direct ground path, did not even look at that for quite a while. However, there does seem to be a strong heat component. I have a very hard FET driven triple that is in a tiny package with a large copper heatsink, that light will work perfectly when disassembled and all parts connected with largish gauge wire. But, when assembled and driven at full power and allowed to heat up for 45 seconds or so the OTC completely stops acting as it should. The head of the light gets very hot, not to hot to touch but uncomfortable and I would suspect if not stepped down it would cause damage to the LED or the driver within 3 or 4 minutes.

Please keep this thought train going, maybe we will get a good re-design and a next generation driver out of the process.

Matt

25

I’m one of those that just creates the PCB in Eagle without a circuit diagram. A circuit diagram does nothing for me. I can understand how it all connects much better by looking at traces and components on a board. I believe wight uses a circuit diagram in Eagle, but may have not published it. It’s really a common circuit that can be found in many forms all over the forum however.

If you want to do prototyping on a breadboard, that’s great! It allows faster progress than waiting for Oshpark to deliver a bunch of times. However, keep in mind if the solution doesn’t fit on a 17mm circle in the end, it doesn’t really solve the problem.

26

Nice ideas, maybe you should have made some points on actual connections of the schematic…its painted correct and I can easyly follow it but only because I knew how it is before.

I don’t see any problems with the minimalistic design we have. I have dozens of Fet drivers like others and they work very stable.
I don’t see the advantages of the pfet in this application.
If you want to make something switchable with a Fet than I would prefer switching of the bleeder when the light is switched on.:wink: so freeing up a pin sounds good:)
I even used higher values for r1 and r2 to reduce standby current in momentary switch lights…

The only real “problem” I see besides the low bleeder is the “heating Otc cap problem”
With measuring temperature in the newer drivers the heating problem could maybe handled via software.
As for the minimum count part if additional parts make real improvements there would be room on the underside of the driver. In former times most drivers had components on the underside, just since wight did his magic with squeezing all the parts on the top we have the luxury of the one sided super driver.

27

Hmm that’s very interesting

28

Well, I personally already use the underside of the driver.

29

If you look at the two drivers in my sig line, I upload a screenshot of the pcb in Eagle. I find those very easy to follow with the low part count on our drivers.

30

That’s basically how your OP diagram would look to me if I didn’t already have the circuit memorized. The 5ohm decoy resistor is my favorite part.

31

out here, there be dragons.
post with extreme caution

AAAHHHHH ! You burned my face off !!

32

First off, no, I can’t contribute anything helpful, it’s over my head.

But I’d be interested to read what you found out about the OTC.

33

That’s one way to become famous.

34

I just found this thread and am trying to catch up on what’s in it… I keep running into a distraction though.

Regardless of the intent, it seems commonly perceived that Sharpie’s communication style is … abrasive, to put it mildly. I mean, I pretend to be a literal goddess, and even I find it condescending.

Sharpie, is there any chance you might be willing to tone that down a bit? It would be much easier to focus on the on-topic technical issues without all the salt being tossed around.

35

Or, to say the same thing more light-heartedly…

That’s very interesting, but this forum consists mostly of humans. I know, I know, it’s weird for me too. But I find it’s much easier to get things done when I try to speak their language.




36

pretending to be a goddess !!! I think not !!!
then who did the magic OTC ???

This is just one flashlight user’s opinion, but I think sharpie is pretty cool.
I think sharpie is Spock with a Glock.
Well…. you know what I mean.

37

I think Sharpie was trying to get the thread back on track (in perhaps an amusingly robotic way).

I think it’s safe at this point to move on and stick to the point of the thread.

This is a flashlight forum after all… :slight_smile: