Hi
I've made the circuit from your link in this free
Circuit Simulator and scaled it up to 30W and using a 36V DC power supply,
to power 24-28 pcs of 3W red LED's and I have designed it around the fact that resistors come in fixed values so it's either 0.33 ohm making the LED's draw 810mA or 0.47ohm drawing 580mA
so unless you parallel mix'em with smaller sizes it a choice between the two.
Increasing the voltage above the suppled 36V will not make the LED's draw more, but gets converted to heat in the regulating mosfet.
In this circuit, as the author describes, it's wise to get as close to the voltage as possible, and I've made two examples
of the wasted heat in the mosfet/resistor and the numbers of LED's
Import this into the sim to play with the circuit if you like.
$ 1 5.0E-6 10.20027730826997 63 10.0 62
v 128 608 128 32 0 0 40.0 36.0 0.0 0.0 0.5
w 256 464 224 464 1
w 176 32 176 128 0
O 464 32 592 32 1
w 176 32 256 32 0
w 304 448 304 400 0
O 304 400 368 400 1
162 256 96 256 144 1 2.45 1.0 0.0 0.0
f 256 464 304 464 0 1.5
w 304 480 304 512 0
w 176 224 176 464 0
w 176 32 128 32 0
w 304 608 224 608 1
w 224 608 128 608 0
t 304 512 224 512 0 1 -13.49573954887927 0.5380034644348117 100.0
w 224 528 224 608 0
w 224 496 224 464 0
w 224 464 176 464 0
r 176 128 176 224 0 100000.0
r 304 512 304 608 0 0.47
w 256 96 256 32 0
w 304 368 304 400 0
162 256 144 256 192 1 2.45 1.0 0.0 0.0
162 256 192 256 240 1 2.45 1.0 0.0 0.0
162 256 240 256 288 1 2.45 1.0 0.0 0.0
162 288 96 288 144 1 2.45 1.0 0.0 0.0
162 320 96 320 144 1 2.45 1.0 0.0 0.0
162 288 144 288 192 1 2.45 1.0 0.0 0.0
162 288 192 288 240 1 2.45 1.0 0.0 0.0
162 288 240 288 288 1 2.45 1.0 0.0 0.0
162 320 144 320 192 1 2.45 1.0 0.0 0.0
162 320 192 320 240 1 2.45 1.0 0.0 0.0
162 320 240 320 288 1 2.45 1.0 0.0 0.0
162 352 96 352 144 1 2.45 1.0 0.0 0.0
w 304 288 288 288 0
w 256 288 272 288 0
w 272 288 272 96 0
w 272 96 288 96 0
w 352 192 352 336 1
w 352 336 304 336 0
w 304 336 304 368 0
w 304 288 304 96 0
w 304 96 320 96 0
w 320 288 336 288 0
w 336 288 336 96 0
w 336 96 352 96 0
w 544 96 560 96 0
w 544 288 544 96 0
w 528 288 544 288 0
w 512 96 528 96 0
w 512 288 512 96 0
w 560 192 560 336 1
w 480 96 496 96 0
w 480 288 480 96 0
w 464 288 480 288 0
w 512 288 496 288 0
162 560 96 560 144 1 2.45 1.0 0.0 0.0
162 528 240 528 288 1 2.45 1.0 0.0 0.0
162 528 192 528 240 1 2.45 1.0 0.0 0.0
162 528 144 528 192 1 2.45 1.0 0.0 0.0
162 496 240 496 288 1 2.45 1.0 0.0 0.0
162 496 192 496 240 1 2.45 1.0 0.0 0.0
162 496 144 496 192 1 2.45 1.0 0.0 0.0
162 528 96 528 144 1 2.45 1.0 0.0 0.0
162 496 96 496 144 1 2.45 1.0 0.0 0.0
162 464 240 464 288 1 2.45 1.0 0.0 0.0
162 464 192 464 240 1 2.45 1.0 0.0 0.0
162 464 144 464 192 1 2.45 1.0 0.0 0.0
w 464 96 464 32 0
162 464 96 464 144 1 2.45 1.0 0.0 0.0
w 256 32 464 32 0
w 560 336 352 336 0
162 560 144 560 192 1 2.45 1.0 0.0 0.0
162 352 144 352 192 1 2.45 1.0 0.0 0.0
s 560 192 640 192 0 0 false
w 560 96 640 96 0
w 640 96 640 192 0
w 432 96 432 192 0
w 352 96 432 96 0
s 352 192 432 192 0 0 false
o 7 64 1 35 5.0 9.765625E-5 0 -1
o 8 64 1 35 20.0 9.765625E-5 1 -1
o 19 64 1 35 1.25 9.765625E-5 2 3
In order to reduce the waste heat, more components are required like an op-amp on the feedback circuit,
in order to get away from the size of R3 controlling the situation 100% and the circuit not being adjustable around
the desired current, but then it start to look like a real driver.
