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# ultrasonic transducer drivining circuit

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#### mamech

##### Full Member level 3
ultrasonic transducer driving circuit

hello

I am wondering, what can be the main components of a circuit that can drive an ultrasonic transducer that is used in cleaning applications??

I looked inside a machine that is used for ultrasonic cleaning, and I found its driving circuit looks very complicated.

those transducers work on frequency range from 28khz to 200khz, with power of 50 to 100 watts. the first idea that came to my mind, that I can make 555 circuit and connect its output to power transistor for example?

I do not know if this idea is naive, because here the frequency and power are relatively high, but I want to know what things that I am missing.

thanks

I believe it would be less effective, to give the transducer a push in one direction, then wait for it to relax passively back to its idle position. This would be driving it with pulsed DC, on-off. A 555 type of output would be like this.

Instead, if possible, I believe the transducer should receive a forcible push in one direction, then the other. This would be driving it with true AC. It could be done by a full H-bridge. I suppose an AC square wave is better than a sinewave.

Perhaps the transducer has a resonant frequency? It should be possible to detect this in a feedback circuit, in order to drive it automatically at the resonant frequency. Such a circuit is not easy to design.

It may be easier simply to drive the transducer with a frequency sweep. And a variety of frequencies may be the more effective strategy to clean objects.

mamech

### mamech

Points: 2
I believe it would be less effective, to give the transducer a push in one direction, then wait for it to relax passively back to its idle position. This would be driving it with pulsed DC, on-off. A 555 type of output would be like this.

Instead, if possible, I believe the transducer should receive a forcible push in one direction, then the other. This would be driving it with true AC. It could be done by a full H-bridge. I suppose an AC square wave is better than a sinewave.

yes, I agree.

Perhaps the transducer has a resonant frequency? It should be possible to detect this in a feedback circuit, in order to drive it automatically at the resonant frequency. Such a circuit is not easy to design.

I think this kind of circuit may have feedback of current for example, and it will keep increasing frequency until current reaches to inflection point (it will be global maximum that happens at resonant point ,I think), and this will be the set point for controller, and will start to make sweep around it. Or if we know already the resonant frequency of the transducer (which is usually the case) we can give this frequency as set point directly to the controller . this is just what I imagine.
It may be easier simply to drive the transducer with a frequency sweep. And a variety of frequencies may be the more effective strategy to clean objects.

yes, correct. I have read this.

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