The presented simple infrared transmitter circuit design can be used in the form of an infrared remote control, with a frequency modulated tone, to operate a complementing IR receiver circuit.
How the Circuit Functions
The transmitting frequency is determined by C1 and adjusted using the trimpot 100k.
The transmitter LED must be of the infrared type and more power can be achieved by connecting two LEDs in series with a series 100 ohm limiting resistor (using no less than 22).
The supply voltage which becomes the operating voltage for the infrared transmitter can also be increased to 9V in order to compensate the presence of the LED resistor.