How to measure piezo impedance #2

Thread Starter


Joined Dec 9, 2021
I have piezo sensor pipe i give 90 v 13.8 kHz sqarevwave to TX how can I receive maximum pick voltage of ultrasound to RX through water how can I match piezo sensor impidence

Moderator edit: New thread created from this.

Audioguru again

Joined Oct 21, 2019
You did not provide the detailed datasheet for the piezo then we know nothing about it.
Many piezos do not work in water since they are designed to be used in air.


Joined Sep 17, 2013
Welcome to AAC!
Are both the Tx and Rx piezos external to the pipe?
How are they acoustically coupled to the pipe? I'm aware that coupling material can provide an acoustic impedance transformer to help match the pipe acoustic impedance to the transducer acoustic impedance (but I'm no expert on this).
Last edited:


Joined Nov 6, 2012
Piezo-Elements act like a Capacitor in a Circuit,
they don't actually have an "Impedance" per-se.

It's a very "small" Capacitance, so I suppose You could say that You need
an Amplifier with an extremely high Input-Impedance.

Audioguru again

Joined Oct 21, 2019
The capacitor diaphragm of a piezo flexes and needs more power to work in water compared to working less harder in air.
So the impedance of the driver circuit must be low enough to provide that power.