In remote control transmitting circuits, there are two types of circuits: an encoder and a 38kHz carrier signal generator. In applications that do not require multiplexing, a limited number of infrared remote control transmitters and receivers can be constructed using conventional integrated circuits. This circuit does not require a complex dedicated codec and is therefore easy to build.
Using a dedicated infrared encoding communication protocol (such as those used in color TVs, VCDs, and DVDs) as an encoder at the infrared transmitter is difficult for general electronics technicians or hobbyists to implement. However, for remote control transmitting circuits with a limited number of channels, a frequency division multiplexing (FDM) method can be used to create the encoder. Furthermore, for a single-channel remote control circuit, an encoder can be omitted; simply transmitting a 38kHz infrared signal can achieve the control purpose.
