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?

  • \$\begingroup\$ Do you have a datasheet? \$\endgroup\$
    – uint128_t
    Feb 1, 2016 at 7:05
  • \$\begingroup\$ I asked seller for datasheet. He sent me this: Model: EU1640BCH Diameter:16MM Nominal frequency ( KHz) : 40 KHz The emission sound pressure at 10V (0 db = 0.02 mPa) :≥110dB The receiving sensitivity at40KHz (0 db = V/ubar) : ≥-75dB Electrostatic capacity at1KHz, < 1 V(PF) : 1800±30% \$\endgroup\$
    – Perry
    Feb 1, 2016 at 7:19

1 Answer 1


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:

ultrasonic transducer cutaway

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.


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