A Circuuit to Drive Ultrasonic Transducers

[mmartens]

I am looking for an oscillator circuit to drive ultransonic transducers, which are going into a processing type of device. This works like an ultrasonic cleaner unit. ( about 40kHz 1000v 400 W) it would be nice to adjust the frequency and power.

 

[nbucska]

You should operate at the resonant frequency of the transducer. Do you have its data ? <nbucska@pcperipherals.com>

 

[mmartens]

Yes, it around 41 kHz.

 

[nbucska]

search at e.g. <

http://www.dogpile.com>

for ultrasonic cleaners
or <

http://www.cleanosonic.com>

<nbucska@pcperipherals.com>

 

[mmartens]

I am not looking for an Ultrasonic Cleaner and I was not wanting to be pulling one apart for the circuit. I am looking for a oscillator circuit to drive ultransonic transducers. For a total different process not quite like Ultrasonic Cleaning.

 

[nbucska]

They sell separate generators, too. <nbucska@pcperipherals.com>

 

[mmartens]

O.K. This is how it goes. The ultransonic transducers are used in a chem. cracking process. The entire process is under the control of a few PLCs which in this case must control the driving frequency (resonant frequency to about 200kHz), a sweept frequency (10 kHz to 1mHz) and different transducers at different times along the process track in given wave forms. The frequencies are adjusted for opt. cracking for given process inputs. I did not want to buy a generator which I have to rip all apart and reengineer for my this process. I did talk to a few OEMs with no luck. I wish it was as simple as buying an off the shelf generator. I just thought that some might have some type of oscillator circuit to start from. Not having to buy something to rip apart and total redesign and wire. Thank-you for the help.

 

[nbucska]

Have you selected transducers ? can you E-mail me the data?
Can the transducer provide enough energy so far off from resonance?
<nbucska@pcperipherals.com>

 

I have made a few oscillators for piezo transducers as in ultrasonic cleaners and these are very resonant systems. I have not much experience with magnetostrictive transducers which are probabdly more effective in industrials situations and possibly more broadbanded. However if you want a variable frequency power output at 400W then something like an audio amplifier commonly used in Hi-Fi would be worth looking at. These may not go the full frequency range you want but I expect the it may be possible to increase that.

 

[mmartens]

Peternz, It would be great to have a look at your oscillator circuits for piezo transducers as in ultrasoniccleaners. thanks

<gmartens@telusplanet.net>

 

[jbartos]

Suggestion: Try
Reference: Marcus J., &quot;Electronic Circuits Manual&quot;, McGraw-Hill Book Company

 

The circuit I used was a 40V Hartley blocking oscillator. Today I would try to make a line voltage oscillator for this application
I have had a quick look through my records but can not readily lay my hands on it. I will look again in the next few days.
Your application sounds like an industrial one in which case I think you should buy proven industrial generators. If you are going to use a bank of generators operating at different frequencies, then I can understand that you will have difficulty obtaining the frequencies you want from manufacturers because they will all work at their design frequency
However if you are short of cash and wanting to develop the circuitry yourself you are in for a lot of work depending on your resources. There a lot more aspects to this apart from making the oscillator.

 

[charliebPE]

Hello Peternz and Mmartens,

Having worked with magnetostrictive transducers and having been frustrated with trying to find reasonable power supplies available off the shelf, I'm designing my own. These comments will apply equally well to a piezo device.

I've chosen an LM555 timer running in astable mode. The output waveform looks more triangular than sinusoidal but the ultrasonic transducer I'm going to drive at resonance will round that off and make it sinusoidal. The LM555 feeds a matched NPN-PNP pair of BJTs that provide the necessary current gain. This output stage is a typical audio amplifier architecture. The customization comes in matching impedances to the unique transducer characteristics.

Charlie
contact@bright-engineering.com

 

[gjones33]

Hi mmartens,

A simple and inexpensive solution would be to program a microcontroller to provide the frequencies you require.

Cheers,

G

 

[nbucska]

CharliebPE:
The sawtooth /\/\/\/\ can be clipped/filtered to get a
rounded /-\_/-\ allmost sinewave with minimum harmonic
content !
<nbucska@pcperipherals.com>

 

[charliebPE]

Nbucska,

Ahh, but I'm cheap! The ultrasonic magnetostrictive transducer itself is my filter. Any harmonics that survive eddy current attenuation will then be severely attenuated because the transducer is driving a waveguide with a non-linear shape, which the math tells me will only resonate at its fundamental frequency.

Also, I changed the electrical design to a single high-powered BJT for gain.

Charlie