This remote tester circuit is based on infrared sensor IC TSOP1738. TSOP1738 contains photo detector and preamplifier both in one package. It is a three terminal device. Pin1 is used as ground pin. Pin 2 is for power supply and pin 3 is used for output. Pin diagram of TSOP1738 is shown below. Take care while connecting the TSOP pins as wrong connections may lead to damage of sensor. Following figure shows the pin diagram of TSOP1738.
Fig. 2: Image Of an Pin Diagram Of TSOP1738 IC
Assemble the circuit as shown in circuit diagram and apply power supply. When power supply is given LED connected at the output starts blinking. When IR waves from remote fall on the sensor, its output changes to low state. This will turn ON the transistor connected at the output and LED will blink according to the button press on the remote. If this phenomenon happens, it means your remote is working fine. Here R2 and D1 are used to limit the current into the sensor. Do not supply more than 5V directly to pin 2 of TSOP1738 else it will destroy the sensor.