IR remote debugger

This device can be used to test all type of IR based remotes like: tv remote, ac remote etc. All types of remote emitt some IR signals which can not be seen by our naked eyes. In the given circuit, IR reciever (D2) is connected in revererse direction. The reciever has the property to change its resistance, as the IR rays fall on it. As we press a remote in D2 direction, IR rays emitted from the remote fall on D2 and its resistance decreases hence V3 increases . As the base voltage of transistor Q1 increases, it gets turned on and hence D1 starts glowing and buzzer beeps.