Hi guys.
I have been working on a project but I got stuck designing a driver for a ultrasound transducer (piezo).
I`m using a piezo like this.
The thing is that I have been designing this by parts. My intial idea was to make something like this circuit.
This simulation actually works. The relay is just to change the frequency of the input. In real world this should not work because MJEs bandwidth is about 1MHz and also they only can handle 150VCE. The pot RV1 should increase or decrease Vin of the load (Piezo). Also here I was considering a piezo as a Resistive load but I was making some research and I realized that they behave as a capacitive load. And it`s resonance frequency is about 1-18KHz so for obvious reasons this should not work for a piezo transducer.
I tried to start over and understand first how transistors behave at this frequencies. And I made this really simple circuit:
The input is a square wave 12 Vpp (minimum is 0V).
And my result is that I get at the output only 0V. But if I add a capacitor I get this:
Question 1:
Why I have to add a capacitor in series to make this circuit work? This is something related to impedance of the transistor on that range of frequencies?
Question 2:
For my first design maybe changing MJEs for other high voltage/high frequency transistors (or even MOSFETs) maybe the circuit could work?
Question 3:
If I change transistors (question 2), and also I change my load adding an inductor to change resonance frequency to make it resonate to a higher frequency? I mean counter the capacitive load of the piezo with an inductor. If this does not help, should I buy a piezo that resonates at 1MHz? Or there is a way to make this piezos to resonate at 1MHz?
Question 4:
Any other idea to drive an square wave that the amplitude can be handled by a pot and also that it has a frequency of 1MHz and 3MHz to a piezo transducer?
Thanks guys for reading my post.
I have been working on a project but I got stuck designing a driver for a ultrasound transducer (piezo).
I`m using a piezo like this.
The thing is that I have been designing this by parts. My intial idea was to make something like this circuit.
This simulation actually works. The relay is just to change the frequency of the input. In real world this should not work because MJEs bandwidth is about 1MHz and also they only can handle 150VCE. The pot RV1 should increase or decrease Vin of the load (Piezo). Also here I was considering a piezo as a Resistive load but I was making some research and I realized that they behave as a capacitive load. And it`s resonance frequency is about 1-18KHz so for obvious reasons this should not work for a piezo transducer.
I tried to start over and understand first how transistors behave at this frequencies. And I made this really simple circuit:
The input is a square wave 12 Vpp (minimum is 0V).
And my result is that I get at the output only 0V. But if I add a capacitor I get this:
Question 1:
Why I have to add a capacitor in series to make this circuit work? This is something related to impedance of the transistor on that range of frequencies?
Question 2:
For my first design maybe changing MJEs for other high voltage/high frequency transistors (or even MOSFETs) maybe the circuit could work?
Question 3:
If I change transistors (question 2), and also I change my load adding an inductor to change resonance frequency to make it resonate to a higher frequency? I mean counter the capacitive load of the piezo with an inductor. If this does not help, should I buy a piezo that resonates at 1MHz? Or there is a way to make this piezos to resonate at 1MHz?
Question 4:
Any other idea to drive an square wave that the amplitude can be handled by a pot and also that it has a frequency of 1MHz and 3MHz to a piezo transducer?
Thanks guys for reading my post.