IR Rays are invisible to human eye, so it is very difficult to check the working of IR LED. Usually we use a Mobile camera to test IR LED since the pink light from the IR LED becomes visible in digital camera. We can make a simple IR LED tester so that, before using it in the project, we can confirm whether it is good or not. Lot of IR LEDs are also in our Junk box. So we can check all IR LEDs and discard the damaged ones. The same tester can be used to check all ordinary LEDs, Photo diodes, Silicon and Germanium diodes etc.
Starting some simple projects for the beginners who are going to start the electronics project building. The first project is a simple LED Tester without any soldering. You can make it in few minutes. With this tester you can check all the LEDs and can also be used as a Light source.
Title of the circuit is deliberately given because it is used for testing the Photo diodes, Infrared LEDs, Photo transistors etc working in “Silent Mode”. How can we confirm an Infrared LED is working or not. It gives No visible indication. It is working and emitting Infrared rays but the IR rays are beyond our spectral response and we can’t see it. So this simple tester will help you to check whether such devices are good or bad before using in a circuit or even during trouble shooting. Not only one function the tester doing . It can test, all diodes, Capacitors, LEDs etc. Its cost is just Rs.10 but it is a worth tool.