piezo driver (high intensity)

[audioguru]

Hi Epilot,
Look again at the graph I attached of the horrible frequency response of a piezo transducer. If you feed it a bunch of frequencies then you might hear some but not hear others. It will reproduce the distorted harmonics of lower frequency fundamental frequencies.
It resonates too much to be a speaker.

Some cheap speakers use a piezo tweeter. They sound like a whistle.
Very cheap speakers have a photograph of a tweeter instead of a real tweeter. They sound better than a speaker with a piezo tweeter. [smiley]

 

[epilot]

Hi Epilot,
Look again at the graph I attached of the horrible frequency response of a piezo transducer. If you feed it a bunch of frequencies then you might hear some but not hear others. It will reproduce the distorted harmonics of lower frequency fundamental frequencies.
It resonates too much to be a speaker.

Some cheap speakers use a piezo tweeter. They sound like a whistle.
Very cheap speakers have a photograph of a tweeter instead of a real tweeter. They sound better than a speaker with a piezo tweeter. [smiley]

Hi audioguru,

yes i know what you mean, and i am agree with you, but i want to use my piezo's with a freq between 39 to 43kHz , i think my piezo's are able to deliver that frequencies, and they are working ok with my circuit on the beard board, but my problem is that my homebuilt soundlevel meter shows a very low pressure of the sound,
when i change the freq to about 7kHz i have the whistle but it is not so much loud

i can remember that i saw an alarm 2 or 3 years ago
using 1 transistor that had a piezo and the transistor was as driver and provided more than 50V for the piezo without any transducer or coil.

by the way, what researchers do when they need for wideband
high freq ultrasonic?

 

[epilot]

I agree with audioguru, but I would use small MOSFETs rather than bjts, but on the CMOS idea I was thinking about this.

but ithink your circuit is like my attach.
these digital IC's are sensitive to border(edge) of the voltage so i think there is no difference between your circuit and mine.
i know that you used from 6 gates to drive the piezo rather than 4,
but i had a test with one free gate in the 4069 and connected it to opne side of my other gates in parallel but without any response,
but i'll make a test with your circuitry and see what will happen

thanks

 

[audioguru]

Since you want to make ultrasonic "sound", then why not use an ultrasonic piezo transmitting transducer???
You can measure its output with an ultrasonic receiving piezo transducer.

 

[Hero999]

6 gates are better because the output impedance is lower so it's louder.

Normal audiable piezo transducers have a sharp peek at about 32kHz, it's easy to find if you know how. You'll need an oscilloscope with a 5mV range, a signal generator, two transducers and a frequency counter (optional). Connect one piezo to the signal generator set at 25kHz 50% squarewave connect the other transducer to the scope and frequency counter, hold it close to the transmitting xducer, tune the sig-gen until the waveform on the scope is perfectly sinusoidal and has the highest amplitude, this is the resonant frequency.

 

[Nigel Goodwin]

6 gates are better because the output impedance is lower so it's louder.

Normal audiable piezo transducers have a sharp peek at about 32kHz, it's easy to find if you know how. You'll need an oscilloscope with a 5mV range, a signal generator, two transducers and a frequency counter (optional). Connect one piezo to the signal generator set at 25kHz 50% squarewave connect the other transducer to the scope and frequency counter, hold it close to the transmitting xducer, tune the sig-gen until the waveform on the scope is perfectly sinusoidal and has the highest amplitude, this is the resonant frequency.

That seems a complicated way of doing it?, and you're measuring TWO piezo's which may be different?.

Simple way is to use just ONE piezo at a time, connect the scope across it, and feed a sinewave generator to the piezo via a resistor - a few kilo-ohm should do. Then adjust the sinewave generator, a sharp null will be it's series resonant point (good for a transmitter) and a maximum peak will be it's parallel resonant point (good for a receiver).

 

[epilot]

i would like to know if i can use from a power amplifier like LM3875?
i want to buy few and try them out

 

[epilot]

Since you want to make ultrasonic "sound", then why not use an ultrasonic piezo transmitting transducer???
You can measure its output with an ultrasonic receiving piezo transducer.

yes i have 2 of them and i am using them, but please be noticed that the problem is improving the sound pressure.

i'll try to see if i can find a cheap sound level meter in commercial to measure the loudness correctly.

 

[Nigel Goodwin]

i would like to know if i can use from a power amplifier like LM3875?
i want to buy few and try them out

You've never told us yet exactly what transducer you're talking about, do you have a link or a picture?.

 

[Hero999]

That seems a complicated way of doing it?, and you're measuring TWO piezo's which may be different?.

There won't be much difference if they're the same type.

Simple way is to use just ONE piezo at a time, connect the scope across it, and feed a sinewave generator to the piezo via a resistor - a few kilo-ohm should do. Then adjust the sinewave generator, a sharp null will be it's series resonant point (good for a transmitter) and a maximum peak will be it's parallel resonant point (good for a receiver).

That will test the electrical resonance which is different to the mechanical resonance.

 

[epilot]

You've never told us yet exactly what transducer you're talking about, do you have a link or a picture?.

i have seen that ultrasonic sensors use from a small piezo ceramic, and i am talking about "piezo ceramic disks

 

[epilot]

who know if dB meters are able to measure the sound presser at ultrasonic freq?
100kHz MAX.

 

[Nigel Goodwin]

i have seen that ultrasonic sensors use from a small piezo ceramic, and i am talking about "piezo ceramic disks

That doesn't help much?, don't you have one yet?.

 

[audioguru]

I don't know of anybody's ears or of a sound pressure meter that measures above 20kHz. Since you can't hear it then its actual sound pressure is not important, you could just increase the gain of the receiver's amplifier if it isn't received strong enough (within reason).

Maybe you should use infrared "light" instead of ultrasonic "sound" for your application.

 

[Nigel Goodwin]

Maybe you should use infrared "light" instead of ultrasonic "sound" for your application.

Does anyone know what he's trying to do yet?.

 

[ajeet]

i need a circuit on ultrasonic cleaning

hi friend
please i am doing the project on ultrasonic cleanig,i need the circuit

 

[ajeet]

hi friend
please i am doing the project on ultrasonic cleanig,i need the circuit