So you are saying if you have a crap constant current circuit you will get crap results. Doh!That is no reasion to abandon the concept.
A simple MOSFET and resistor provides much better solution than using CC driver in this application.
Quote from: mjkzz on Mar 26, 2013, 10:56 amA simple MOSFET and resistor provides much better solution than using CC driver in this application. No, a mosfet, transistor and a couple of resistors configured as a linear constant current regulator provides a better solution (although if you are running the IR LED from a regulated supply, then a mosfet and series resistor is adequate). But you are correct in that the usual switching regulators are not designed to be modulated at 38kHz.
I was able to set up the circuit with a 2N3904 transistor. I'm using external power. The circuit works, I can see the LED flashing with a digital camera, but the flash is very weak, less than using it directly on Arduino PIN.