D.I.Y. Illuminated tailcap

The bleeder is usually a tiny 0603 resistor and on the top side of the driver, thus it would be very hard to adjust. Better to use a fixed resistor there and a pot on the tailcap where it is much easier to access.

My understanding is the bleeder goes between + and - to allow power for the tailcap to bypass the driver. There was a Rev of the tailcap board with two 3x3 pots on it. I was wondering if that could be modified to be a bleeder pot and a brightness pot instead of 2 channels for the leds. If you change the brightness with the pot, wouldn’t you need to change the bleeder value to compensate?

The bleeder has to be on the driver as that is where the positive normally gets cut off.

The pots on the tailcap are only for controlling LED current, having 2 of them allowed you to control 2 different colors of LED separately.

Now the rev 5.3 is the “standard” board and it uses a single pot to control brightness for the tailcap and fixed resistors to adjust the current for each channel.

So, do the tailcap LEDs cut off when the switch is closed due to the internal resistance of the LEDs, so the current takes the path of least resistance (the switch)?

I’m trying to figure the best way to connect an LED strip under the optics in the head to illuminate the front as well. Do you think if I connected the pos (on LED strip) to the pos lead from the driver going to the main LEDs and then ran a neg lead from an empty pad on the driver (with neg current of course) to the LED strip that would work? Maybe I should draw it out on paper as something seems off when I do it in my head.

I don’t see any way to switch your led strip in the head on when the tail cap switch is off. Is that what you’re hoping to do?

I have a problem with my illuminated tailcap and fet+1 driver with blf a6 firmware. I noticed that when battery is fully charged, it take 8 seconds to go backward at medium tap and around a minute for long tap to reset to the first mode. But when the battery is around 3.6v or below, everything’s back to normal, med tap (1 sec) and long tap (longer than 1 sec).
What’s wrong with that? Maybe the bleeder resistor I used? It is 470ohms for the bleeder and 3.9k for the tailcap led.

Yes, you will have to fiddle with bleeder and tail resistor values to solve that. Since those timings do not go to infinity but still are measurable, you are not that far off a workable set-up. Perhaps going to 10K for the tail already makes it work fine with still a good amount of light coming from the tail leds.

Here is a chart I put together from various measurements I took at different resistance levels to see what the corresponding current is. I tested 4 different colors of LED’s, White and blue will be inline with the green and purple results. Orange will be along the lines of the yellow and red.

From my testing as expected Green, blue and white put out a lot more light for a given current. At 0.04ma of current these colors are MUCH brighter and do indeed need a 100K pot to get them as dim as many want but the Red, yellow and orange on the other hand are almost too dim at .1ma.

Click for larger version:

I agree overall, but I question your manufacturer of Reds, yellow, and oranges. Blue and green are def brighter, but I still get great brightness from reds and oranges at 0.03-0.06ma

It is possible, I had the same basic results from several different brands from digikey, Arrow and then I ordered 100 of each color from that ebay link that was posted awhile back. Those are what I am using now, except for purple, they are very inconsistent with purples.

Yeah I have never had luck with purple. Either way, great chart. I should send you some of my Lighthouse leds to add to your experience

If you want to send them I can keep them on hand, although I am out of the PCB’s and have no funds for more at the moment. Although I have tons of springs, switches, leds and pots to build them with lol. I am sure I will order more PCB’s at some point.

Thanks, I’ll try 10k for tail leds and see what will happen.

Short Version
Help, please! Need assistance adding a bleeder to a MTN17DDm-NUV FET+1 driver. Photos of an installed bleed resistor on this driver would be greatly appreciated.

Long Version
The current build is a beautiful blue Convoy S2+ with a triple XP-L HI and the aforementioned driver. I had the bleeder installed and seemingly working fine, then after one day of usage my driver fried (after a small drop, so the bleeder may or may not have been to blame). I had soldered the bleeder between D1 and the outside ground ring. The placement was less than ideal because of interference with the pill’s rim when tightening the retaining ring - addressed by a couple solder blobs around the grounding ring to build up the surface, but it seemed to work… for a while.

I then ordered a new replacement driver and decided to steer clear of the rest of the components and instead added it between the spring and a small area where I scraped away some solder mask. Everything looked fine and dandy, but when I installed the driver, the 7135 was acting up. After some diagnosing (via a custom firmware to test the output of the 7135 and FET channels), it appears that the 7135 would only output a small amount. Feeding it PWM values of 10, 100, and 255 all resulted in the same very dim output (all of them being less than the PWM 10 output of the FET channel). Seems like something was perhaps messed up with the PWM output of the MCU to the 7135 channel? Since I added the bleeder before ever installing the driver, I have no way of knowing if the bleeder did something, or if the driver was already defective.

I’m about to order a couple more drivers: one for this build, one for an Astrolux SS triple build. I’d really not like to mess up any more drivers. These buggers aren’t exactly cheap. I may end up not doing a tailcap in the S2+ (the very low visibility through the metal tailcap was disappointing), but I’m definitely going to want it for that Astrolux SS triple build. Any input you guys have would be awesome. Thanks!

Why not simply get a driver that has a bleeder spot on the driver?

The Texas Avenger has a bleeder resistor and so does the tripledown (although I would recommend the TA for the triple build). Plus building them yourself you will save money as well.

If you need a single sided driver the TA driver can be used without the 7135’s on the bottom populated.

IIRC you can stack the bleeder on the C1 as well although from the spring to the ground ring should be fine as well.

I’ve given serious consideration to that, TA. I was just giving them a look earlier this morning. This sounds a bit ridiculous, but I just feel like they have more than I’m looking for at the moment. I guess I’m just not ready to step my game up to a triple-channel just yet :wink: But given any more difficulties, I’ll probably take the plunge (though maybe just a single-sided version for simplicity sake).

Installing the bleeder over C1 was actually the very first thing I tried. But it didn’t work properly for me. I think it may be how C1 and D1 are ordered in Richard’s driver.

LOL, well the TA series is really not any different from the MTN17dd from the UI standpoint. Only the mode groups are different in the UI.

As far as the rest of the driver goes the triple channel really doesn’t effect anything except the firmware, which is already taken care of. And like was said, you can leave the bottom side 7135’s off if you want, although I would recommend that you use them if you can, they really do add a nice high regulated mode.

Any chance someone here has tried adding one of these to a light with a lux-rc v5 driver? I’ve got a light I’d like to do this to, but I’m a bit apprehensive because its more expensive than most of what I tinker with.

I’ve already posted about this build in another thread, but I couldn’t help but add a quick pic here too. I put a lighted tailcap in a Sinner Tri-EDC today. Its one of the larger 6-emitter boards with all warm-white emitters, mounted under an orange translucent tailcap.

I’m about to order Rev5.3 will post if I get it working in a build thanks PD