IR_REMOTE_TESTER

Published:2009/7/14 7:25:00 Author:May | From:SeekIC

This remote handset tester is very useful and convenient, and could quickly pay for itself by helping to recover faulty remote handsets. Pulsed infrared light generated by the handset falls upon D1, which creates a pulse waveform across R1. This is capacitively coupled to the base of TR1, and an amplified signal is coupled to C2 to a pulse-stretching circuit based around TR2, C3, and associated components. Hence, driver transistor TR3 conducts and illuminates the LED D2 whenever infrared light is received by D1. A functional remote controller with fresh batteries will operate the tester from approximately 500 mm, while one with nearly exhausted batteries may work over only a few centimeters. Coincidentally, the design also self-tests its own battery by giving an initial flash of D1 when the switch S1 is first closed. The IR photodiode should be roughly a 940-nm type, while the types of the transistors themselves are not crucial. The circuit will operate from a 6- to 12-V rail (e.g., a 12-V battery), and C4 decouples the power supply rails.



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