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 3 IR LEDs through a Darlington transistor BD 139(which includes BC 547 and BC 557(N ) 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 (which
includes BC 547 and BC 557(N ). 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.
This simple infrared transmitter circuit uses 3 IR transmitter LEDs connected in series to increase the power. The mosfet BS170 which act as a switch, has been used to increase the circuit efficiency. Data (CMOS-compatible) tobe transmitted is used for modulating the 38kHz frequency generated by CD4047 (IC1).
Here the long range/distance Infrared transmitter circuit, give you extra power for your Infrared transmitter. The majority of the IR remotes do the job reliably within a range of 5 metres. The circuit complexity increases in case you design the IR transmitter for good operation more than a extended distance.
Previous: Chapter5 Long Range IR Transmitter
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