This cirucit is same as that of the last circuit, with only a single difference that the encoder in the above circuit is replaced here with 2 Dual D Flip flops.
The working of this circuit is that, when any one crosses before the pyroelectric infrared sensor, then a signal can be send through a radio transmitter and it can be received at a very long distance in a receiver. So, this circuit can be used for security even in remote areas.
In the circuit diagram, B is an Pyroelectric(PIR) sensor. It is a motion sensor, which detects the movement of human. This sensor can be placed in an security needed place. When anyone moves, immediatley the PIR sensor gives a signal to IC1, which is a Dual D flipflop, From IC1, the signal the reaches to TWH8778. TWH8778 is a switching IC. When the signal comes through control pin 5, it immediately closes and the signal can be send to the IC2, which is again a Dual D flipflop which toggles the signal. Then, the signal is amplified for transmission with IC KD9562, and is passed to IC4 .BA1404. is an stereo transmitter IC, which transmitts the signal from the PIR sensor.
In the receiver side, there will be a same set up with a receiver antenna to receive the signal from PIR sensor. This circuit is mainly used in ARMY, NAVY and in country borders for security purposes.