thanks Mr.Mike for suggestion, late night i just make that circuit and doing well (though i place a 12v/35W Automotive bulb).
check the voltage accros the Bulb there is 3,4V and the Current can steady in ~2A.
but is that circuit can operated well if i place 3 High Power in Series? (3,7V/3A per Led) because the voltage must be 10,2V ?
i try to change R2 (FET Bias) from 100k with 100k Potensiometer, try to tuning out and the stupid happen, i got the Potensio has blow up and fire. haha!
and FET + NPN Transistor has die. so i build up again. (My Bad).
no, i mean that VR / Pots just to make the Output voltage in nominal that i want. like if i just plug 1 LED so i tune it to 3,7V. if i plug 3 LED then i tune it to 11,2V.