This Infrared transmitter can activate IR based switching circuits from a distance of 10 meters or more. It is a high power IR transmitter driving two IR LEDs through a Darlington transistor BD 139 to increase range and directionality.
IC CD 4047 is wired as an Astable multivibrator and its output pulses depend on the values of C1 and VR1. By adjusting VR1 the output frequency can be adjusted from 10 KHz to 60 KHz. High output from IC1 is available from its Q output (Pin 10) which is used to drive the NPN Darlington transistor BD 139. Resistor R4 restricts the power of IR LEDs to a safer level. Q_ (Pin 11) is the complimentary output of IC1 which is used to connect the indicator LED which flashes in sympathy with the IR signals.