hi h.y,
Why have you have reduced the supply voltage from 12v to 5v.?
Have you tried reducing the On period of the 1MHz drive.?
E

I have reduced the voltage to 5V because, ultimately, i have to make everything working on 5V only, I cannot use a 12V supply as it will be battery operated.
No, I haven't tried reducing the on period yet, but eventually, I will do that.
I am having some trouble in calculation for transformer, as it tuns out there are no 1 Mhz transformers used yet, so I cannot understand, which core to use, wire gauge and no.of turns...can you help me out with it as per your high skills and experience.

Thanks..

 

I am guessing that the real problem is that the transducer is somehow not being driven, with the result being a lack of signal and a lack of echo. At any rate, that is worth investigating, since the results that you have been having are not reasonable. And it seems to me that the very low impedance is not reasonable either. I have seen unreasonable results as the result of unknown connections existing, and so I suggest checking all the connections, especially the grounds, to be certain that they are only connected where you intend them to be connected.

 

I am guessing that the real problem is that the transducer is somehow not being driven, with the result being a lack of signal and a lack of echo. At any rate, that is worth investigating, since the results that you have been having are not reasonable. And it seems to me that the very low impedance is not reasonable either. I have seen unreasonable results as the result of unknown connections existing, and so I suggest checking all the connections, especially the grounds, to be certain that they are only connected where you intend them to be connected.

Hi MisterBill,
Thanks for replying. I took your advice and reconnected everything again, with proper ground connections keeping in mind how sensitive this transducer are. Still, after trying so many times, I did not get any result on the steel container (Beer Keg)...

 

I did not get any result on the steel container

I suspect that most of the acoustic energy is being 'soaked up' by the container. The big acoustic impedance mis-match between the steel and the keg liquid content will act as a 'mirror', so little energy will enter the liquid.

 

hi h.y,
With the 5Vsupply limitation this is the best result for such a basic circuit.
I would recommend that you review the design proposal for this project, in trying to measure the water height in a metal container, through it's base.

E

EDIT:
Added asc file.

 

hi h.y,
With the 5Vsupply limitation this is the best result for such a basic circuit.
I would recommend that you review the design proposal for this project, in trying to measure the water height in a metal container, through it's base.

E

Hi Eric Gibbs,

Thanks for replying.
Can you please share with me the .asc file of the circuit to simulate?

See my Edit.

 

Hi Eric Gibbs,

Thanks for replying.
Can you please share with me the .asc file of the circuit to simulate?

See my Edit.

Hi Eric,
I have done slight changes to the file .asc, like changing the duty cycle to 50% and removing the 0.1 ohm resistor at supply, please check and let me know your views on it....

 

hi,
Have you compared the two simulation plot images.???

What is the piezo output for the first 10uS of the input drive signal.???

With respect, you seem to be totally ignoring what I am advising you to do, I cannot help you further with this project.
E

 

hi,
Have you compared the two simulation plot images.???

What is the piezo output for the first 10uS of the input drive signal.???

With respect, you seem to be totally ignoring what I am advising you to do, I cannot help you further with this project.
E

Hi Eric,
I apologize that you feel so, but I can assure you that your guidance in this project is very valuable to me, I don't mean to ignore your results, as I am limited with the resources, that is the reason I make changes and ask your inputs on it.
Yes, I see a drastic change in the two plots.

 

hi h.y.
I would recommend that you try the actual circuit to drive the piezo on the container, use your scope and observe the TX pulse and Echo as you vary the On time of the drive pulse.
At the moment we are assuming what the response of a simulated piezo will be in the real hardware when it is not mounted on the container.

So, get some actual results from the hardware and post.

E

 

hi h.y.
I would recommend that you try the actual circuit to drive the piezo on the container, use your scope and observe the TX pulse and Echo as you vary the On time of the drive pulse.
At the moment we are assuming what the response of a simulated piezo will be in the real hardware when it is not mounted on the container.

So, get some actual results from the hardware and post.

E

Hi E.G,
I tested the circuit and got the following output results. Please check the attachments

 

hi,
If you have used the circuit in post# 148 with a 0.5Usec On period, your image 'when piezo connected' , shows what I have been posting, it does not work.

What is the piezo output for the first 10uS of the input drive signal.???

The only period when the piezo 'rings' is at the end of the 10uSec, 10 pulses burst.!

E
Compare your actual image with is LTS image, it shows the same problem.

 

hi,
If you have used the circuit in post# 148 with a 0.5Usec On period, your image 'when piezo connected' , shows what I have been posting, it does not work.

What is the piezo output for the first 10uS of the input drive signal.???

The only period when the piezo 'rings' is at the end of the 10uSec, 10 pulses burst.!

E
Compare your actual image with is LTS image, it shows the same problem.

The LTS circuit & Simulation results for the scope images of post #151 is as follows...
I have showed the output of two different piezo transducers in post #151, the image named "Another 1 MHz piezo Output" is the output with a different 1 MHz piezo...

 

Why are you transmitting a 10-pulse burst rather than a single pulse?
BTW, you can increase the pulse amplitude by increasing your driver pulse 'on' time to, say, 2.5uS and changing M2 for a higher Vds rated one.

 

I have not read all 154 comments, but what my experience driving a piezo element in a different situation is that at resonance the amplitude of vibrations increases with the number of drive cycles, up to some point. So if a low amplitude is part of the problem then having a few more cycles at resonance could be useful. Probably 5 cycles would be adequate, though.

 

EDIT:

hi Danko,
Could you please post an image showing the 10 drive pulses on the same time scale at images you have posted.
Or the asc file if possible.
Eric

Below is piezo.asc file:
EDIT: added file piezo+IRFP264_model.asc

 

hi Danko,
Could you please post an image showing the 10 drive pulses on the same time scale at images you have posted.
Or the asc file if possible.
Eric

 

hi Danko,
Please do not read my posts as criticism of your circuit, it is an interesting point of discussion.

The circuit is ringing at approx 650kHz, which is well off the 1mHz required, as the field collapses on L1.
Any returning Echo will not be 1MHz, so it may create only a weak signal for the receiver.
BTW: I am showing a peak power of approx 90Watts, I believe the TS has only a 8Watt piezo [ perhaps he could confirm that.??]

It would be interesting if the TS, tries your circuit and see how it works in real time.

Eric

 

Hi Eric & Danko,
I will try the circuit and share the results. The simulation looks quite good though.
The piezo I have is of 30 Watts.

 

Hi Eric,
Frequency is shifted down to 650kHz, because of transducer model,
which changes its parameters under the influence of other circuit components,
but real piezo will work just stable (mechanical resonance only).
In circuit used well known burst mode with damped oscillations,
when piezo is activated by one pulse shock excitation.
Usually average transduser power dissipation should not exceed 125 mW
(OLYMPUS transdusers), and voltages should be not more then
50V per mil thickness.
So, pulse voltage may be up to 600V, depends on transduser type.