How can I test ultrasonic transducers

Discussion in 'General Electronics Chat' started by julio_w, Apr 9, 2013.

  1. julio_w

    Thread Starter New Member

    Apr 9, 2013
    Hi All,

    I am trying to build a large ultrasonic cleaning bath, I already bought 50 PZT transducers 60 Watts and 40 Khz each from a supplier on china, and I am going to buy a 3 Kw ultrasonic generator to connect all transducers in parallel.

    So before buying the large generator I wanted to test the transducers one by one just to be sure that what i get is what i order, so I decided to buy from ebay one small ultrasonic cleaner of 50 Watts 40 Khz and then I was thinking in replacing the transducer with the new ones one by one and test.

    So my question is how do I test? I know you can do the foil test but that will just tell me that there is ultrasound going on but I want to know the actual frequency of the transducer. So can I just buy a transducer receiver that cost around 2$ and connect at the terminals an oscilloscope? not even sure if that is possible.

    Thanks for reading and I would appreciate your help.
  2. julio_w

    Thread Starter New Member

    Apr 9, 2013
    I found this schematic for a bat detector, they claim they can detect up to 100 khz and basically divide the frequency by 16 to get an audible signal...


    So I was thinking that if that is true I could do something similar eliminating the frequency divider, ear plug, etc and if I attach an oscilloscope at the exit of IC2 i should be able to measure the frequency, am i right?
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    If you have an oscilloscope, you should be able to measure frequency directly at pin3 of IC1. Or even without the circuit if your scope is sensitive enough (just connect the o-scope probes across the transducer leads.
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    I think 50 piezos driven together at 3kW in a closed container is not really a beginner project!

    You can't test high power devices for resonance without having them in water etc, and even then the resonance may also be influenced by your finished container size, and maybe even what is placed in it...

    Maybe you should make a little ultrasonic bath for experience, with just 1 piezo in it running at 50W?
  5. Geowizard

    New Member

    Nov 30, 2014
    So, are we detecting bats or blasting debris with a piezoelectric transducer? o_O

    Bats are interesting creatures (mammals like us) that emit sounds for the most part above the limits of human hearing. The bat receiver is an interesting project that divides down ultrasonic frequencies to our range of hearing.

    Back to a "rational" approach to a high energy ultrasonic cleaning system...

    Piezoelectric transmitters generate a significant high voltage pulse to the piezoelectric crystal. In order to test the crystal, it should be immersed in a bath similar to the envisioned cleaning bath dictated by (hopefully) a pre-planned design spec. Too great of pulse will fracture the crystal and it will be ruined. Since manufacturers perform end-item testing on piezo-transducers, their "data sheet" should also describe a suitable test fixture (including circuit diagram).

    Hope that helps!
  6. ian field

    AAC Fanatic!

    Oct 27, 2012
    If all you want to do is verify correct resonant frequency, build a TTL crystal clock oscillator with test leads to the device under test instead of a regular crystal unit.

    If the transducer is dodgy in some other way, it may just fail to oscillate.
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    What is going on around here with all of these threads rising from the dead. The OP hasn't been back in 18 months. He didn't even respond to the questions when it was 'active', does anyone expect him now?
  8. wayneh


    Sep 9, 2010
    I don't know. This used to be rare. Now it's daily. I wonder if something about the new forum layout has made it more likely.