I need to modify the schematic below to accommodate for the change from 6 5mm IR Leds to a single 5w LED star.
Previous 5mm LEDs
High output infrared LED 5mm 1.2VDC 100mA 940nm
New 5w LED Star
Emitted Color : Infrared IR 940nm
Viewing Angle: 135 degrees DC
Forward Voltage (VF): 1.4V DC
Forward Current (IF): 1400mA Maximum
Pulse Voltage: 1.7V
Maximum Pulse Current: 2000mA
Since this is a strobe I want to be running it at ~Pulse Current. My power supply will be a cigarette lighter outlet in a vehicle, which I believe gives out around 13.5v.
Just replace those diodes with the single one and recalculate the 6R8 resistor.
Finally the BD135 will be dissipating a whole shed load more power so it needs to be a bigger transistor with more power dissipation and on a large heat sink.
If you could drop the input voltage then that would reduce the power dissipation substantially.
See this 6R8 resistor?
It defines current, I = 0.7 / R = 0.7 / 6.8 = 100 mA
So, for you:
R = 0.7 / I = 0.7 / 1.4 = 0.5 Ohm.
Use appropriate wattage resistor, and Darlington TIP120 in place BD135, don't forget heat think,
as it gonna to dissipate around V x I = 12 x 1.4 = 17 W