Ultrasonic Transmitter and Receiver
THE Ultrasonic Transmitter circuit shown in Fig. generates ultrasonic sound waves at a frequency of 40kHz. The key component is a 555 timer, IC1, which is wired as an astable to produce an output frequency of 40kHz. This stream of electrical signals drives the ultrasonic transmitter transducer TX1. Potentiometer VR1, used as a variable resistor, enables you to make fine adjustment to the frequency when setting up the control system to ensure that TX1 is resonating at its optimum natural frequency, thereby ensuring maximum range. This adjustment is described in the ‘synchronising’ section at the end of the receiver section. Ultrasonic Receiver: The circuit shown in Fig. is designed to receive and process the 40kHz pulse of sound waves generated when the transmitter’s pushswitch is pressed. On the first push the relay is energised, and de-energised on the next push, enabling an electrical device to be switched on and off via the relay contacts. The Receiver circuit comprises the fol...
