1.6 ohm resistor for LM317?

[GonzoEngineer]

Your desk looks like mine!

(BRW, there are a lot of new, cheap plastic lenses out there now for these new high power LED.)

 

[Willbe]

Use your digital probe

With the LED on full time, it does get hot.

Below 36°C probably feels cool to the touch
no burn @42°C
burned in:
30 seconds @ 54°C,
5 sec. @ 60°C,
1 second @ 71°C.

Components with less heat capacity need higher temps to get the same effect.

 

[Leftyretro]

Well the nicest thing I've seen for driving 3 watt LEDs is this driver from sureelectronics on E-bay. Fixed contant current with a optional PWM input terminal so you can easily dim it if you want. Can drive from one to five diodes in a series string.

**broken link removed**

Lefty