I have EU1640BCH12T/R waterproof ultrasonic sensors, which I have got from this link. These are standalone raw sensors without breakout board and not a module like HC-SR04. Being a new electronics hobbyist, I want to test these sensors with Arduino for distance sensing. I tried replacing transmitter and receiver of the original HC-SR04 module with my these ultrasonic ones but I am getting very ambiguous outputs from the circuit. Please suggest what circuit do I need to make to test these raw waterproof ultrasonic sensors?
I think that either the transducer Q factor is too high for the board (extra inertia due to the metal case), causing a pulse to become abnormally long, or the transducers fail to efficiently couple acoustically with the air (impedance mismatch), causing a weak ultrasonic pulse and even weaker reception. Internally a transducer looks like this:
With the little horn being key to efficient coupling. At 40 kHz the wavelenght is just 330 m/s / 40 kHz = 8.25 mm.
Can you measure the terminals of the transmitter with an oscilloscope, and compare the results with the original transducer?
However I think that those transducers should work in open air with a proper controller as they are probably of the same design being used as parking sensors.
Designing an ultrasonic rangefinder is not a trivial task and is beyond the scope of a reasonable answer.