I am using a non inverting amp with B class voltage follower to drive a piezoelectric transducer (used as sonar for fish scanning in boats). I am using trains of 20 sinewave pulses (85KHz), like the ones you can see in the blue image (input).

[![enter image description here](https://i.stack.imgur.com/9Ghxf.png)](https://i.stack.imgur.com/9Ghxf.png) 

However, at the output I am getting the green signal, which have undesired residual oscillations with the same frequency. The problem with this, is that the receiver circuit amplify the full incoming wave with a large gain - and there is no way to difference the 20 pulses from the "blank" space. This jamming effect is screwing up the data transmission.

The circuit I build in PCB is this:

[![enter image description here](https://i.stack.imgur.com/J8bTK.png)](https://i.stack.imgur.com/J8bTK.png)

I have discovered in simulation that if I decrease the value of the decoupling capacitor, in theory the oscillation tale dissapears. I will try this in the real circuit, but I would like to know which is the correct way to deal with this.

BTW, these parasitic oscillation just happens when the transducer is plugged in the circuit. I am pretty sure isnt related to the operational amplifier.