This circuit is an excellent electronic circuit for Baby monitoring. The main components of the circuit are: The PIR sensor, The audio oscillator and the antenna. The PIR sensor is fixed beside the cradle or beside the baby. Till the baby sleeps, there wont be any signal in the circuit. When the baby moves, immediately the sensor alerts the VT1, which gives signal to audio oscillator KD9300 . Immediately, the oscillator generates asignal at a particular frequency and passes it to antenna, and the antenna conveys it to the receiver.
This circuit can also be used for security purposes.