OK, so swapped the 180K R3 for a 100K - now getting 7.6-7.7 amps at the tail - little overshoot, but decided to test it anyways.
Throw went up from 652 kcd to 712 kcd, lumens from 885 at start to 960 at start (calibrated #'s).
So what else could be keeping the throw # down? Still well centered, good looking hot spot. The centering piece - it's a bit high, and the style of have a curved cup around the LED, and it's colored white. So decided to sand it down a little:
- base from 0.96 mm to 0.85 mm
- sanded top down - took off 0.03 mm (little)
- overall height from 1.83 mm to 1.69 mm
New numbers:
- 725 kcd (1703 meters), taken at 5 m
- 996 lumens at start, 954 lumens at 30 secs (temp calibrated, raised max)
As you can see, it doesn't drop much over 30 secs, and the droppage slowed down to a crawl at 30 secs (expected for this kind of regulated driver). Lumens is quite lower than what djozz measured, but could be from several things:
- maybe I got a lower bin LED
- my cheaper light meter may be under measuring green
- my PVC lightbox may have issues with throwers
- etc...
Now it's performing to Hank's spec. I would experiment with the centering piece more, but I got no backup, so afraid I'll make it worse then have no way to go back.
A resistor value of 120K for R3 may be ideal for this green LED. These are 0603 sizes.
4.8 -> 7.6 for change of 180K to 100K. If it's somewhat linear, 120K should be about 7.0 amps which is the peak on djozz's chart. Hhmm - might have to go with that. I bought a huge collection of 0603 resistors so I got a ton of sizes and about qty 50 of each size.