I need a 17mm contact board to adapt a new driver to a light I'm trying to mod. The original was a proprietary type driver that I could have utilized part of, but wrecked it before I realized how I could have adapted it.
All I need is a 17mm contact board to solder onto the original brass ring that is needed to press-fit into position in the head.
I found this 17mm contact PCB which is pretty standards with a pos. center ring, and neg. outer ring. This should be perfect.
But now my problem is the underside. Most contact boards have more or less the same configuration on the backside, but this one seems to have the pos. center connecting to the neg. outer ring area. I need the outer area on the underside to be soldered to a brass ring to complete my neg. circuit.
Can someone explain how the underside connection is set up? Why is the center connecting to the outer edge where I need my neg. connection?
Could I mount it upside down, just using the center for the spring to attach to?
Are there any other 17mm contact boards out there?
The layout; I can't think of a reason to have the positive contact carry over so far towards the edge, unless it's for a particular component or solder method.
Wait, what's wrong with the board pictured in the first post? The front & back are only connected where the vias (the little holes) are, the center and outer are completely isolated. Yes it's meant to be for a tailcap switch - how would a switch work if the middle and outer were connected before the switch was soldered on?
If the 'T' part of the center pad interferes with your mounting ring, just grind it off.
I decided I’ll mount it upside down. The full encircling neg. ring on the PCB will give me better contact with the brass fitting ring, and I’ll only need the top to mount the contact spring. I think it’ll work okay…fingers crossed.
Well, that 17mm contact board served well, although I did have problems. I hooked it all up, tested it with leads from a battery holder, works. Pressed it into place, doesn't work. Pulled it out, works. Pressed it in, doesn't work. I finally figured that it had to be the circuitry on the driver, which comes right to the edge of the board, shorting on the battery tube. I slathered Fujik thermal paste all over it, and I now have a nice little 14500 Nichia Clickie with a 1.0A buck boost driver.
Before I pressed it in for the final time, the driver was coated with thermal paste and allowed to dry.
So, if anyone needs a 17mm contact board, this one serves the purpose.
Using thermal paste as an insulator is a VERY bad idea. It will eventually wear through/shift/whatever. You can possibly wind up with a dead short across the battery… which can turn your light into the proverbial pipe bomb.
You are no fun at all. but I agree. Thermal Adhesive (2 part epoxy) would work, since it would be tough enough to hold up, or even some Kapton tape might work well.
I’ll take it under advisement, but I think I’ll leave it as is. I slathered the Fujik pretty thick, and let it dry for three days. There is really no room left in that small tube for any movement at all. The first sign would be that the light won’t come on.
It is certainly a valid concern, but I think in this particular case it is a worst case scenario. I promise to pay close attention, and use protected cells.
With that alleged contact board, I would definitely cut (or even better totally remove) that etch between the center pad and edge (dremel tool makes it easy). That pad near the edge could easily make contact to a driver ring, pill edge, etc.
but I agree. Thermal Adhesive (2 part epoxy) would work, since it would be tough enough to hold up, or even some Kapton tape might work well.