Here is a long range Digital IR transmitter. It is a precision IR transmitter suitable for TSOP 1738 IR receiver module. Unlike other IR transmitters, this circuit is highly reliable and gives fail proof operation.
The IC used in the circuit is the MOS IC uPD6121 which uses the NEC transmission format to suit with IR receiver systems used in TV and VCD player. The IC is a low power version works off 2-3 volts and takes little current as low as 1 uA giving long life to the battery. Output of the IC can be used to drive IR LEDs using driver transistor. The circuit is crystal controlled enhancing its precision in frequency. IC oscillates in the 38kHz frequency.
The NEC transmission format of the IC includes leader codes, 16 bit custom codes, 15 bits data codes etc. It has 32 codes single inputs, 3 codes double inputs, expandable up to 64 codes through the SEL PIN 7.Crystal is connected between the OSCO (Pin8)and OSC1 (Pin9).
The NEC transmission format includes leader codes, custom codes (16 bits), and data codes (16 bits).The frequency of oscillation is determined by the Crystal. The IR LEDs connected to the output emits IR pulses at 38kHz.The circuit is ideal for most IR Sensors since these are designed for 38 kHz pulsed IR rays.
Filed Under: Electronic Projects