dc42:
There are a few online stores that sell underwater ultrasonic transducers, e.g. in the UK Maplin and Rapid sell this one http://www.rapidonline.com/Electronic-Components/Underwater-ultrasonic-transducer-200KHz-plastic-case-35-1810/?source=googleps&utm_source=googleps.
hi, this seems to be an expensive sensor by itself (without the module) is there a cheaper alternative for this?.. and If Suppose I will buy this, can I replace the sensor of an ultrasonic sensor module with this???