Here is a simple tester to test the IR Sensor TSOP 1738. It is a highly sensitive device that damage easily if its input voltage rises above 5V. This Tester can be used to test TSOP 1738 before using in a circuit. It confirms the condition of the Sensor, whether it is functioning properly or not. It can also be used to check the IR Sensors kept in your junk box so that you can keep only the good one for use.
The tester is so simple. It is an IR Module circuit but instead of the IR Sensor module, a three pin socket is used for testing the sensor. Green LED lights when the tester is powered using 9V Battery. TSOP 1738 gives high output when not receiving Pulsed IR rays of 38 KHz. Output voltage will be around 3.3 V at 20 mA current. When the Sensor receives IR rays, its output sinks current and output voltage turns zero.
Insert the Sensor module in the Test socket with correct polarity. Regulator IC 7805 gives steady 5V DC for the Sensor under test. When the IR transmitter emitting 38 KHz IR beam is focused, RED LED blinks if the sensor is a good one otherwise, the Red LED remains dark.