Ultrasonic Beam Barrier Circuit

Posted on Feb 5, 2014

This circuit generates inaudible ultrasound to make a barrier across the entry. At the moment the circuit detects a break in the sound barrier, it generates a loud alarm indicating the entry of a person. This can be used to protects the entry passages and helps to detect unauthorized entry of persons in protected areas. The circuit has two section

Ultrasonic Beam Barrier Circuit
Click here to download the full size of the above Circuit.

s. An Ultrasound transmitter and a receiver. Both the circuits use 40 kHz Ultrasound transmitter (TX) and ultrasound receiver (RX) pair to transmit and receive the ultrasound. The Transmitter section uses the ultrasound transmitter TX in conjunction with an emitter coupled oscillator comprising T1 and T2, both BC 548. The values of resistors and capacitors determine the oscillation at 40 kHz frequency which exactly matches with that of the transmitter. The receiver section has a 40 kHz ultrasound receiver RX which is connected to the base of T1. It is a common emitter amplifier which amplifies the signals received by the RX. The amplified signal available from the collector of T1 is coupled via C2 to the signal detector stage comprising T2, D1 and C3. When RX continuously receives the ultrasound from TX, T3 remains saturated and conducts. This keeps T4 output conduction since its base is at ground potential. When the ultrasound beam breaks, T3 turns off and T4 conducts. The piezo buzzer connected to the collector of T4 sounds the alarm. Red LED indicates the standby mode showing that the alarm system is active.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Speed regulator for dc motors
    Antialiasing And Sync-Compensation Filter
    AM portable Reciever Using ZN414
    economy radar detector
    Digital voltmeter using ICL7107
    OPB350 Tube Liquid Sensor
    Centrifugal fish autofeeder
    FM Modulator Circuit
    Hyper-Simple Battery Capacity Tester
    FM24C256 interface circuit