Here is the schematic. Place the voltage regulator in a good heat sink.
With the LM350 I can change the voltage with the 5k variable resistor and at the same time I have the ammeter connected to make sure the amps will not raise 1.7A. (The LED is rated 1.8A but just to be on the safe side)
PLEASE NOTE : I found a problem on the schematics, there shouldn't be connection between the anode of the 1n4001 and the negative of the 10uf.