IR Receiver:

TSOP1738 is a infrared receiver tuned to receive IR of frequency 38 kHz only. It is perfect for making obstacle sensors and to read signals from most IR remotes(TV, AC, Home Theatre Remotes, etc). When used as a receiver in distance sensors, it provides better performance as it allows better reception and protection from ambient light compared to other IR receivers. It can be used to read signals of most IR Remotes.

The TSOP1738 IR sensor module consists of a PIN diode and a pre amplifier which are embedded into a single package. The output of TSOP is active low and it gives +5V in off state. When IR waves, from a source, with a centre frequency of 38 kHz incident on it, its output goes low. Lights coming from sunlight, fluorescent lamps etc. may cause disturbance to it and result in undesirable output even when the source is not transmitting IR signals. A bandpass filter, an integrator stage and an automatic gain control are used to suppress such disturbances.TSOP module has an inbuilt control circuit for amplifying the coded pulses from the IR transmitter.