High Power Piezoelectric Ultrasonic Transducer Driver

Thread Starter

Elazar

Joined Oct 29, 2019
15
Hi Everybody,

I am working on a project that needs to drive 5 (175 watts) Piezoelectric Ultrasonic Transducers, the system needs to output clear ultrasonic sound at 40 kHz (precise sine wave)

The system needs to produce a very clear sound (of course not for the human ears) of 40 kHz sine wave

Currently, I have these transducers from Aliexpress https://www.aliexpress.com/item/32978115507.html?spm=a2g0s.9042311.0.0.49fc4c4dCArXYp

Product size and performance parameters:
Model: CH-S42-50x2.6
Resonant frequency (kHz): 40 ± 1
Static capacitance (pF): 8000 ± 10%
Resonance impedance (Ω): ≤20Ω
size: 50 * 2.6mm (diameter * height)
Power (W): 35w
Insulation resistance (2500V DC): ≥ 100MΩ

Does anyone have an idea of how we can drive these transducers from a simple 40KHz sine wave generator (1v p-p)

I thought to try to use a high power audio amplifier, for example of 300W output with a high bandwidth (< 60kHz) and connect the output to a high-frequency transformer to step up the voltage, so the question is, will this work?

Do you have any suggestions/advice about how to do it?

Can piezoelectric ceramic ultrasonic transducers as in the link above produce clear/clean sine wave sound?

Do you think anything else might be better (to produce good sound quality)?

Any help will be highly appreciated!
 
Last edited:

AlbertHall

Joined Jun 4, 2014
8,834
Five 20 ohm transducers in parallel would be 4 ohms - a good value for feeding with an audio amplifier so no transformer needed.
 

Thread Starter

Elazar

Joined Oct 29, 2019
15
Hey Albert

Usually, Piezoceramic Transducers like this need a very high voltage of 150 p-p voltage?
Will a regular amplifier work for this?
Also, it will be a highly capacitive load, will this work for a regular amplifier?
 

AlbertHall

Joined Jun 4, 2014
8,834
The spec says the capacitance is 8nF - impedance at 40kHz is about 500 ohms.
Also it says the transducer impedance is <= 20 ohms so the capacitance makes little difference to the effective impedance.
 

TeeKay6

Joined Apr 20, 2019
532
Hi Everybody,

I am working on a project that needs to drive 5 (175 watts) Piezoelectric Ultrasonic Transducers, the system needs to output clear ultrasonic sound at 40 kHz (precise sine wave)

The system needs to produce a very clear sound (of course not for the human ears) of 40 kHz sine wave

Currently, I have these transducers from Aliexpress https://www.aliexpress.com/item/32978115507.html?spm=a2g0s.9042311.0.0.49fc4c4dCArXYp

Product size and performance parameters:
Model: CH-S42-50x2.6
Resonant frequency (kHz): 40 ± 1
Static capacitance (pF): 8000 ± 10%
Resonance impedance (Ω): ≤20Ω
size: 50 * 2.6mm (diameter * height)
Power (W): 35w
Insulation resistance (2500V DC): ≥ 100MΩ

Does anyone have an idea of how we can drive these transducers from a simple 40KHz sine wave generator (1v p-p)

I thought to try to use a high power audio amplifier, for example of 300W output with a high bandwidth (< 60kHz) and connect the output to a high-frequency transformer to step up the voltage, so the question is, will this work?

Do you have any suggestions/advice about how to do it?

Can piezoelectric ceramic ultrasonic transducers as in the link above produce clear/clean sine wave sound?

Do you think anything else might be better (to produce good sound quality)?

Any help will be highly appreciated!
The ad at AliExpress says these are for ultrasonic cleaner use. I believe that means they must be operated while immersed in a cleaning fluid (perhaps water & alcohol?). Is that how you intend to use them?
Your first problem is not how to drive them (although that may in fact be a big problem), but how to mount them. They require specific mounting to operate per the specs, and that mounting is not so simple as soldering a couple of wires to them.
Did you do any "homework" (e.g. searching the Web) on mounting and using these devices before you decided to buy them? I wish you good luck but I think you have a serious challenge before you.
 

Alec_t

Joined Sep 17, 2013
10,611
High power piezos are commonly the frequency-determining elements of self-resonant driving circuits.
What will these transducers be used for, that requires them to produce 'clean' ultrasound? If driven at their maximum power their output may include harmonics.
 

TeeKay6

Joined Apr 20, 2019
532
High power piezos are commonly the frequency-determining elements of self-resonant driving circuits.
What will these transducers be used for, that requires them to produce 'clean' ultrasound? If driven at their maximum power their output may include harmonics.
@Elazar
I agree with @Alec_t but I further note that each device will have its own unique resonance, near--but not at--40.00KHz. The devices have a high Q, meaning that if you drive them off-resonance the efficiency will drop dramatically. Since each device will have a different resonance, it will be impossible for a single driver to get high efficiency from each device, unless some means is found for tuning the resonance of each to exactly the same frequency. Also, if each disk is driven at its unique resonant frequency, the combined "sound" will no longer be a pure sine wave at any specific frequency.
 

Thread Starter

Elazar

Joined Oct 29, 2019
15
The ad at AliExpress says these are for ultrasonic cleaner use. I believe that means they must be operated while immersed in a cleaning fluid (perhaps water & alcohol?). Is that how you intend to use them?
Your first problem is not how to drive them (although that may in fact be a big problem), but how to mount them. They require specific mounting to operate per the specs, and that mounting is not so simple as soldering a couple of wires to them.
Did you do any "homework" (e.g. searching the Web) on mounting and using these devices before you decided to buy them? I wish you good luck but I think you have a serious challenge before you.
Hey TeeKay,

Exactly! This is the main concern, will these transducers work in free air?

I thought to use these transducers (only) because of it's high power (35W) small density, the project needs very high power sound in a very small density (smallest possible).

Do you think there are any other options for producing a high power (small density) clear ultrasonic sound (sine wave)?

(Maybe I can order some custom made transducers?)
 
Last edited:

MisterBill2

Joined Jan 23, 2018
4,579
A very high level sound at 40 kHz can be very damaging to both human and animal ears. Signals like that have been used as weapons on several occasions. What is the application intended for this system? It sounds a lot like a weapon system to me. At the very least it would be as unsafe as a non-isolated line fed power supply.
 
Last edited:

Alec_t

Joined Sep 17, 2013
10,611
the project needs very high power sound in a very small density (smallest possible).
Why? There will be a large acoustic impedance mis-match between the transducer face and the air, which will restrict the signal dramatically. Also, further to what TeeKay said about differing resonant frequencies, unless all transducers emit exactly in phase there will be constructive and destructive interference affecting their composite output.
 
Last edited:

Thread Starter

Elazar

Joined Oct 29, 2019
15
A very high-level sound at 40 kHz can be very damaging to both human and animal ears. Signals like that have been used as weapons on several occasions. What is the application intended for this system? It sounds a lot like a weapon system to me. At the very least it would be as unsafe as a non-isolated line fed power supply.
Hi Alec_t,

Is there any research to back that up?
I didn't find any research that above 30kHz might be dangerous?
 

Thread Starter

Elazar

Joined Oct 29, 2019
15
Let's get back to the main question:

What is the best way to drive these transducers - at lease 175 watts?
 

Tonyr1084

Joined Sep 24, 2015
3,942
@Elazar I think you need to answer @MisterBill2 's question. I'm thinking the same thing. There was a point in time where I considered the possibility of using an ultrasonic cannon to aim at my neighbor's dogs. If - When - they barked I could hit them with a momentary blast of pain that would teach them not to just bark because dogs bark for no reason. I was quickly shot down on that thread.

Sound pressure waves at any frequency high enough can cause damage. Just because an individual can not hear it doesn't mean it's harmless. You can't see, hear or feel microwave transmissions. But if exposed to high enough power levels you are cooked ham.

Please answer the question "What do you intend to do with this device?" If it is a noble cause we'd be happy to help. As long as it is not dangerous or intended to be weaponized; we'd be happy to help.
 

MisterBill2

Joined Jan 23, 2018
4,579
@Elazar I think you need to answer @MisterBill2 's question. I'm thinking the same thing. There was a point in time where I considered the possibility of using an ultrasonic cannon to aim at my neighbor's dogs. If - When - they barked I could hit them with a momentary blast of pain that would teach them not to just bark because dogs bark for no reason. I was quickly shot down on that thread.

Sound pressure waves at any frequency high enough can cause damage. Just because an individual can not hear it doesn't mean it's harmless. You can't see, hear or feel microwave transmissions. But if exposed to high enough power levels you are cooked ham.

Please answer the question "What do you intend to do with this device?" If it is a noble cause we'd be happy to help. As long as it is not dangerous or intended to be weaponized; we'd be happy to help.
Years ago I did assemble a device that produced a very loud ultrasonic sound. I could feel it but not hear it, dogs a half block away would jump, and my poor sister would cover her ears and yell for it to stop, even at some large distance. And that was without using a parabolic reflector to direct the sound. Now the US Army has experimented with a similar approach to stop enemy troop charges. So it seems that the concept is valid, and anything that produces that much pain must be doing a bit of damage. So yes there is verification that ultrasonic sound can be damaging. Just because I do not list chapter and verse for things does not mean that they are not correct.
 
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