This Arduino library can be used to emit NEC without a carrier wave. This is useful to send IR NEC commands without an infrared led directly over a wire, typically into 3.5mm / 2.5mm headphone jack.

#include <IRremote.h> const int IR_SEND_PIN = 3; // Define the Arduino Nano PWM pin for IR LED void setup () { Serial.begin (9600); // Start the Serial Monitor for debugging IrSender.begin ...