Ultrasonic Radar is used as an obstacle detector using ultrasonic frequency.  This project brings you the latest application in the field of security systems. Also it can be used as a burglar alarm for homes etc. It consists of a set of ultrasonic transmitter and receiver transducers, which operate at the same frequency. When any object moves in the area covered by the circuit, the circuit’s fine balance is disturbed and the alarm is raised.

The circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm.
About the Circuit :

• The circuit of Ultrasonic Radar is shown in figure. Transmitter and Receiver use ultrasonic piezoelectric transducers as output and input devices respectively and their frequency of operation is determined by the particular devices in use.
• The transmitter is build around two NAND gates of the four found in IC3 which are used here wired as inverters and in the particular circuit they form a multivibrator the output of which drives the transducer. The trimmer P2 adjusts the output frequency of the transmitter and for greater efficiency it should be made same as the frequency of resonance of the transducers in use.
• The receiver similarly uses a transducer to receive the signals that are reflected back to it the output of which is amplified by the transistor T3, and IC1, which is 741 op-amp. The output of IC1 is taken to the non inverting input of IC2, the amplification factor of which is adjusted by means of P1. The circuit is adjusted in such a way as to stay in balance as long as the same as the output frequency of the transmitter. If there is some movement in the area covered by the ultrasonic emission, the signal that is reflected back to the receiver becomes distorted and the circuit is thrown out of balance. The output of IC2 changes abruptly and the Schmitt Trigger circuit which is build around the remaining two gates in IC3 is triggered. This drives the output transistor T1, T2, which in turn gives a signal to the alarm system. The circuit works from 9-12V DC and can be used with batteries or a power supply.

Calibration :
Trimmer P1 is set at its middle position. Turn then P2 slowly tills the LED lights when you move your fingers slightly in front of the transducers. Adjust then P1 for maximum sensitivity. Connecting together pins 7 & 8 will make the circuit to stay triggered till it manually reset after an alarm. This can be very useful if you want to know that there was an attempt to enter in the place, which are protected by the radar.

Ultrasonic Radar is used as an obstacle detector using ultrasonic frequency.  This project brings you the latest application in the field of security systems. Also it can be used as a burglar alarm for homes etc. It consists of a set of ultrasonic transmitter and receiver transducers, which operate at the same frequency. When any object moves in the area covered by the circuit, the circuit’s fine balance is disturbed and the alarm is raised.

The circuit is very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is reset manually after an alarm.
About the Circuit :

• The circuit of Ultrasonic Radar is shown in figure. Transmitter and Receiver use ultrasonic piezoelectric transducers as output and input devices respectively and their frequency of operation is determined by the particular devices in use.
• The transmitter is build around two NAND gates of the four found in IC3 which are used here wired as inverters and in the particular circuit they form a multivibrator the output of which drives the transducer. The trimmer P2 adjusts the output frequency of the transmitter and for greater efficiency it should be made same as the frequency of resonance of the transducers in use.
• The receiver similarly uses a transducer to receive the signals that are reflected back to it the output of which is amplified by the transistor T3, and IC1, which is 741 op-amp. The output of IC1 is taken to the non inverting input of IC2, the amplification factor of which is adjusted by means of P1. The circuit is adjusted in such a way as to stay in balance as long as the same as the output frequency of the transmitter. If there is some movement in the area covered by the ultrasonic emission, the signal that is reflected back to the receiver becomes distorted and the circuit is thrown out of balance. The output of IC2 changes abruptly and the Schmitt Trigger circuit which is build around the remaining two gates in IC3 is triggered. This drives the output transistor T1, T2, which in turn gives a signal to the alarm system. The circuit works from 9-12V DC and can be used with batteries or a power supply.

Calibration :
Trimmer P1 is set at its middle position. Turn then P2 slowly tills the LED lights when you move your fingers slightly in front of the transducers. Adjust then P1 for maximum sensitivity. Connecting together pins 7 & 8 will make the circuit to stay triggered till it manually reset after an alarm. This can be very useful if you want to know that there was an attempt to enter in the place, which are protected by the radar.