D.I.Y. Illuminated tailcap

It was my second and last attempt at hot dedoming the 219C: after the dome broke off halfway I started breaking away and slicing with the scalpel until a thin but messy layer was leftover on the die, and then I cut away all the silicone on the sides, including the white stuff, leaving the gold-coloured underground exposed. It works fine though

I just ordered some blue smd 805 leds and now I was thinking of using one blue and one red led. The blue one would switch off under 3.2V, with the red one still going, sort of lowish voltage indication, as discussed before. I can easily hack that onto the existing board (will do that), but it can also be build in. This would need a extra resistor pad on the circuit board so that the two leds can have their own resistor. The long middle trace could be left there to keep the possibilty of the parallel leds, and just needs cutting if two separate led circuits are used.

How’s this Djozz?
Will work with the led’s in parallel by placing a single resistor on either of the “R” pads, or cut the trace down the middle and the two sides will function as separate circuits. I did the same with the 20mm, and also added the same improvements from the earlier 17mm board.

17mm

And 20mm:

Great work, and clever use of the via's!

With this one you can even make some visible reverse polarity check, provided that the switch is off when inserting the battery: mounted one led in one direction, and a different colour in the other direction, if the battery is wrong it will show a different colour.

Hmm, actually the current setup has that already: battery wrong=leds do not light up.

Btw, would this trick with the bleeder resistor at the driver and larger resistor on the tail board provide enough power to use an e-switch on the tail without too much parasitic current?

I’m not sure what you mean. E-switch on the tail?

Wouldn’t it cease to function when the light is on just like the LED’s?

I look forward to someone telling me I’m an idiot and forgetting something, because it’d be a great option for HO lights.

You only have two paths from the tail to the front of the light, the tube and the battery itself. You can’t carry batt+, batt-, and the signal from an e-switch without running another wire. I have toyed with the idea of putting the whole driver and e-switch on the same PCB in the tail, but I think that would require some tiny 0603 parts to get it all to fit, and my Eagle skills aren’t anywhere close to that level yet.

Yes, I see now why the e-switch idea will not work.

Ordered the new version btw :-)

I just wanted to order parts but it’s not clear for me what are the best parts.

Should I order 0603 LEDs or bigger ones? If I understand it correct the solder pads are big enough for 0805 but you used 0603. why?
I have found that: http://www.ebay.de/itm/121507128509
5colors 10 each white green blue red yellow

I will order some omten1217(or whatever FT ships now).
From cnqg some translucent caps which are linked in OP.

I have some 560ohm resistors in 1206 will these work or is smaller better?

I have 17mm rev2 on order but will also order the newest version with additional pads.

I used a 0603 LED the first time because it was what I had at the moment. It is designed for 0805 size. 0603 will work, but they are just harder to solder and easier to lose.

The Omten 1217 will work with the 20mm board, but it won’t fit on the 17mm. I usually use the Omten 1288.

You should be able to make a 1206 resistor work, the resistor pads are slightly larger than 0805 (but still not 1206 sized)

So I should order 0805 leds…that’s a valueable tip as I have to order things anyway.
I have one 1288 spare but cnqg is out of stock for some more so if anyone knows a good source I would be happy.

I will order the kohm set from fastech which is linked in the OP for the LED resistors which seem to be in this range, but the 560ohm is the bleeder resistor which is necessary I thaught…?

I misunderstood what you said the first time.

Yes you’ll need something close to 560ohm. I use 560, others have used 680ohm with success. 1206 should work perfectly for the bleeder resistor.

I got the 17mm rev2 boards today, all other parts are still on the way so I used a nichia 119, a 5.6kOhm resistor and made a spacer from some plasticsheet.
All together fitted in one of the “scrap” lights I had lying around with the standard gitd boot.

I didn’t need a bleeding resistor it worked with a standard nanjg(the 4*7135 variant). is this always the case? Is the bleeding resistor only for more brightness?

This is a very cool invention! It glows and is very easy to find in the dark.

On our common drivers the input capacitor basically does what the bleeder resistor would do. However, the lighted tail can cause problems for mode-memory on drivers that use an off-time capacitor. For your driver (which doesn’t use an OTC), all the bleeder would do is possibly make the tail a little brighter.

I’ve got a question on this regarding the resistors. Picked up the “value pack” from fasttech, and a good portion are not labeled in a way that I can read them.

For the bleeder resistor, assuming I need one, the closest resistor I could find is a 510k. What is stumping me is that I have some labeled 510k and some labeled 510r. What is the difference as it applies to this build?

This is what I have:
fasttech resistor pack

510R is 510 Ohm (the one that you want), 510K is 510 kiloOhm, so 510,000 Ohm.

For the unlabeled ones, you can read the value using the colored bands then label them.
resistor color code calculator

Or use the next best cheap multimeter with an Ohm (resistor) range to measure the value. (Choose one with autorange if possible for quicker results.)

I think the link for the clear spacers has changed. But if any body wants any of those I now have 99 of them left :wink: I’m sure I’ll use more but probably not all.

Thanks, that makes sense now. I did come across that digi-key calculator, so it is helpful. I don’t think I’ve ever tried ohm resistance testing with my multimeter, so I’m definitely learning new things here.

I was planning on using the white plastic spacer thing that came with my solarforce tailcap. I’ll have to modify it slightly, but it should work. I’ll post some photos of my progress, will have to break out the macro lens, these SMD components are tiny!

~D