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i want to do several projects using ultrasonic ceramic discs but i need a 1.7mhz driver

Thread starter #1
Ok, so here is what i have http://www.ebay.com.au/itm/281484077053?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

and here is one example of the discs in a device http://www.ebay.com.au/itm/351127425403?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649



I have several projects lined up which i want to experiement, such as an acrylic extruder end for 3d printer (printing paints), differently shaped foggers, and atomizers of substances other that water, and a few other things.

i would use the humidifier but its set in resin.


Anyways, i cant find any reliable (to me) looking details on how to use the piezo, its my understanding that i should be applying 24vdc oscillated at 1.7mhz in order to get it working. is that true? in which case how do i generate the signal and at what pwm?
 

MikeMl

Well-Known Member
Most Helpful Member
#4
no its definitely mhz, its an ultrasonic humidifier disc, also if it were kiloherts it would be audible.
More likely it is MHz (MegaHz, 10^6Hz). mHz is milliHz (0.001Hz).
 
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Reloadron

Well-Known Member
Most Helpful Member
#6
You may want to give this a read. I have seen references to 1.667 MHz and driving a H-Bridge to excite the disk. You may be able to find yourself a good used function generator or other source to drive the H-Bridge. That would be my guess as to a starting point anyway.

Ron
 

Externet

Active Member
#7
Yes, it is ~1.7 MHz; and wrongly named ultrasonic as is far enough from sound, but in the RF band.

These are cheap enough to canibalize their drivers or use complete----> http://www.mainlandmart.com/foggers.html
I have one for aeroponics.

Edited-added: By the way, if you figure out how the water level enabling sensor works; please share ! :nailbiting:
 
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KeepItSimpleStupid

Well-Known Member
Most Helpful Member
#8
From the specs the OP gave:
Product Description
  • Item Condition:NEW
  • New Φ20mm Ultrasonic Mist Maker Fogger Ceramics Discs with Wire & Sealing Ring
  • Diameter: Φ20mm
  • Thickness: 1.24 ± 0.01mm
  • Frequency: 1.7MHz
  • Quantity: 1pcs
M=Mega
m=milli
H is for a proper name, "Hertz". hence capitalized.
 

JimB

Super Moderator
Most Helpful Member
#9
Externet wrote:
Yes, it is ~1.7 MHz; and wrongly named ultrasonic as is far enough from sound, but in the RF band.
I disagree. The ceramic thing is mechanically vibrating, it is definitely ultrasonic.

RF as in RADIO? Sorry no way. Radio is electromangetic, this is definitely mechanical, above the normal hearing range, so it is ultrasonic.

Some years ago I visited the hospital to have an ultrasound scan of some of my "bits".
At the end of the session the ultrasound nurse asked me "Any questions?"
So I asked, "What frequency are you using for that?"
The reply was something like 13MHz for one test and 4.5MHz for the other.
Ultrasonics extends to quite high frequencies.

JimB
 
Thread starter #11
I know with absolute fact it is MHz, megahertz, i opened an existing module up, and ran my piezo off its input and it worked, and my scope said it was 1.7MHz.

I also tried running 80V square wave through it but was unsuccessful, though i did not confirm if i actually was outputting correctly, ive since bought a gate driver for my mosfet to try again, but, what sort of waveform do i need for the piezo?

ive been told that just 12 or 24v might actually be enough and i should discharge an inductor through it, but i dont know enough about piezos to do anything with this information. what do i do? i have the oscillator and confirmed the frequency, i also tested the output of the prebuilt pond fogger and it spikes at about 100v, from memory it looked perhaps like the sort of output you get from running square wave through an inductor or transformer.

specifically, what kind of circuit should i be constructing to apply the power in a way that the piezo will accept? should i just try making a small transformer to control with a mosfet bridge? and put the piezo on the output?

One other thing ive heard which would conflict with this idea is that some designs use a capacitor in series with the transducer and i am completely unfamiliar with how capacitors work in series in oscillating circuits.
 

kubeek

Well-Known Member
#13
Guys, please, you are almost four years late to the thread. Jpoopdog, i suggest you start your own thread for your own question, and link to this one if you want to point out any of the posts. Start yours by listing anything you know about the transducer, that is the most important information of all.
Cursory advice, yes piezos are usually run with step up transformers to get the high voltage they usually require. Transformer in the MHz range is not a trivial design. Mosfet bridge likewise.
 

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