+ Post New Thread
Results 1 to 15 of 15
  1. #1
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Ultrasonic transducer driver

    Hello folks! I am new in this area in analog domain...

    I have piezo ceramic ultrasonic transducer for humidifier...

    Specs:
    Voltage: 5-12V
    Res. Freq: 1,7 MHz
    Res. Impedance: <2""> I dont now what is this...
    Coupling factor> 52%
    Static capacitance: 1800pF

    I want to make driver for this transducer as simple as posible. Do you have any idea?

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 53,078, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,979
    Helped
    2583 / 2583
    Points
    53,078
    Level
    56

    Re: Ultrasonic transducer driver

    A full H-bridge is the convenient method to create AC from a single DC supply. It's a variation of the astable multivibrator.

    You can adjust values so large supply current goes through a load.

    Click image for larger version. 

Name:	astable H-bri LC load 8V supply 4 transis op amp auto-reson 1MHz.png 
Views:	6 
Size:	47.5 KB 
ID:	156088

    Your specs mention a resonant frequency. To clarify how oscillations are created through a load, my simulation has an inductor & capacitor load.

    The op amp automatically detects the LC resonant frequency. It does so by sensing zero crossings in the low-ohm resistor.


    1 members found this post helpful.

  3. #3
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    Thanks! This is fantastic!

    Can this example generate 1,7MHz?



  4. #4
    Super Moderator
    Points: 53,078, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,979
    Helped
    2583 / 2583
    Points
    53,078
    Level
    56

    Re: Ultrasonic transducer driver

    Quote Originally Posted by marestudio2004 View Post
    Can this example generate 1,7MHz?
    My schematic illustrates a concept of operation, an automatic method to detect resonant frequency. Where I have a series LC, there needs to be the correct model for your transducer.

    Or instead you may decide it's easier to construct a 1.7 MHz oscillator, to drive a transistor (or mosfet), which sends pulses of current to your transducer. There are types of the 555 timer IC which can create up to 2 MHz.

    It's a question what is the proper waveform to apply, whether true AC, or whether pulsed DC.

    You also need to consider what components can operate at the speed you require. Not every op amp can attain 1.7 MHz.



    •   AltAdvertisement

        
       

  5. #5
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    Specs of driver:

    Input: 9-12v DC
    Output: Sinewave (AC), 9-12v, Freq of signal 1.7MHz



  6. #6
    Super Moderator
    Points: 53,078, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,979
    Helped
    2583 / 2583
    Points
    53,078
    Level
    56

    Re: Ultrasonic transducer driver

    This driver starts with a square-wave oscillator. Frequency is adjustable. (It does not auto-detect resonant frequency.) You must find a frequency which gets best response from the transducer.

    A capacitor filter turns it into a quasi-sine. A series capacitor blocks DC so that AC bias is applied to the half-bridge.

    Click image for larger version. 

Name:	2-invert-gate oscill cap filter quasi-sine half-bri 12 ohm load.png 
Views:	2 
Size:	37.3 KB 
ID:	156161

    If you're willing to make a +10V -10V bipolar supply, this method is simpler than driving a full H-bridge.



  7. #7
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    This is nice solution, Colpitts OpAmp: OPAMP_01.PDF



    •   AltAdvertisement

        
       

  8. #8
    Super Moderator
    Points: 78,448, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,912
    Helped
    3610 / 3610
    Points
    78,448
    Level
    68

    Re: Ultrasonic transducer driver

    Hi,

    Please review the schematic .... best if you do this before uploading it.
    There are a couple of mistakes.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  9. #9
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    Quote Originally Posted by KlausST View Post
    Hi,

    Please review the schematic .... best if you do this before uploading it.
    There are a couple of mistakes.

    Klaus
    Ok, I am not expert in this area, please help to review if you can...



  10. #10
    Super Moderator
    Points: 78,448, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,912
    Helped
    3610 / 3610
    Points
    78,448
    Level
    68

    Re: Ultrasonic transducer driver

    Hi,

    Whatīs the idea of V1?
    It seems the schematic is made with a simulation tool. Why not simply start the simulation to see if/how it works?

    Mind: You post a schematic (named: "This is nice solution") in a forum. Many people see it and try to build it.
    Please feel responsible for the informations you post. Thus my kind recommendation to verify it before you post it.


    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  11. #11
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    Okay, sorry for the writing method ...

    The main idea is described in my first post.

    So a driver for a ceramic piezo transducer with the given characteristics.

    I have mentioned several times before that I am not an expert in this field.

    My posts are mostly about finding a solution (i.e. help ), from people who are experts in this field.

    Given scheme is an example of the Cholpitts OpAmp oscillator, simulated in Proteus. The simulation does not work properly.

    V01 is just internal name of this example...



    •   AltAdvertisement

        
       

  12. #12
    Super Moderator
    Points: 78,448, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,912
    Helped
    3610 / 3610
    Points
    78,448
    Level
    68

    Re: Ultrasonic transducer driver

    Hi,

    V01 is just internal name of this example...
    No, "V1" is the name of a voltage source connected to the output of the amplifier.

    ***
    I repect that you not that experienced, and that you are looking for a solution: And this is all right the way it is - nobody is perfect.
    But on the other hand you write "This is nice solution" (letīs me think that you tested this and itīs working well for you) and then "The simulation does not work properly".... somehow contradictory in my eyes.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  13. #13
    Newbie level 4
    Points: 44, Level: 1

    Join Date
    Oct 2019
    Posts
    7
    Helped
    0 / 0
    Points
    44
    Level
    1

    Re: Ultrasonic transducer driver

    Misunderstanding. The name of the PDF document eventually contains 01, I meant version 01 .... Never mind.

    The forum should be a place that can help people. Unfortunately, I'm going to have to spend a lot of time reading professional literature to come up with a solution.

    All the best.



  14. #14
    Super Moderator
    Points: 78,448, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    15,912
    Helped
    3610 / 3610
    Points
    78,448
    Level
    68

    Re: Ultrasonic transducer driver

    Hi,

    To your problem.
    I miss a "power" or "current" specification.

    In the headline you ask for a "driver". But you post a schematic with an OPAMP used as socillator.
    Is the OPAMP suitable as driver? Or are you still looking for a driver?

    Is your problem solved?

    ***
    About forum:

    The forum should be a place that can help people.
    I agree. (Iīd like to underline the word "help".)
    And a forum is meant that not only the OP gets help, but additionally all other visitors with similar problems by reading through your thread.

    Unfortunately, I'm going to have to spend a lot of time reading professional literature to come up with a solution.
    Yes - thatīs the usual way. Call it unfortunaltely or sadly...

    A forum canīt replace school and can't replace reading books or working through tutorials. And a forum is not meant that others do your job. It is meant to help.

    ****

    I compare it with climbing on a mountain:
    Letīs say you want to climb a mountain. You will find others also climbing the mountain.
    And maybe there are some difficulties - then everybody will lend you a hand (for free) to help you to get over the problem.
    But no one will carry you all the way up - unless you pay for it.

    And maybe there is a difficult place on the way up the mountain and you find it useful (for you and for others) to fix a rope around a rock. (ie posting a schematic).
    It should be tested and solid .. to give others a benefit. Otherwise others may get hurt more than without the rope.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  15. #15
    Super Moderator
    Points: 53,078, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,979
    Helped
    2583 / 2583
    Points
    53,078
    Level
    56

    Re: Ultrasonic transducer driver

    A Colpitts (or Clapp, its cousin) oscillator requires many adjustments of values, to get 1.7 MHz. Then to get oscillations started and sustained also requires a lot of adjusting. These produce a sinewave, however the waveform does not necessarily have the correct voltage range, or sufficient power, to send a few Watts at 10V through your transducer. (Internet articles suggest 2-4W of power for a humidifier transducer.)

    A Colpitts is able to generate a bias waveform sufficient to drive a half-bridge or H-bridge. By doing more adjustments you might succeed at amplifying the sinewave sufficiently without distortion or clipping, as it drives your transducer.

    In contrast, notice how easy it is to arrange two invert-gates (post #6). Make the resistor a potentiometer adjust.

    My schematic shows one capacitor as a one stage low-pass filter, however if you want a better semblance of a sinewave, then add one or more similar stages.



--[[ ]]--