On 18/06/2011 22:45, David wrote:
> I wish to drive a IR LED at 40khz (essentially the Sony IR protocol),
> somewhere between 50mA and 100mA max LED Ifwd.  In testing I have been
> using a 2N7000.

FWIW, if the distance is not too far you can get reasonable results=20
using a couple of PIC pins for IR modulation. I breadboarded a little=20
Sky remote controller a while back, IIRC using one PWM pin for the=20
modulation connected via resistor and IR LED to another pin to sink or=20
block the current thus controlling the mark/space. Worked okay. No=20
MOSFET and one resistor.
I guess it depends on the distance requirements. Maximum current is=20
usually around 25mA per PIC pin.

--=20
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